阅读说明：本技术 光学通信系统、光学收发器、光学通信方法和非暂时性计算机可读介质 (Optical communication system, optical transceiver, optical communication method, and non-transitory computer-readable medium ) 是由 富田功 于 2019-11-25 设计创作，主要内容包括：本光学通信系统缩短在启动系统时或者在替换或新增加光学收发器时设定光学收发器之间的波长所需的时间,并且减少准备用于新添加或替换的光学收发器的类型。第一光学收发器(1)在切换第一光学信号的波长的同时将第一光学信号输出到光纤(3)侧,光纤(3)侧是充当用于承载与与第一光学收发器(1)相对的第二光学收发器(2)的单核双向通信的介质。当第一光学信号的波长成为能接收的波长时,第二光学收发器(2)识别所接收的第一光学信号的波长,并将具有基于识别结果确定的波长的第二光学信号输出到光纤(3)侧。一旦第一光学收发器(1)从光纤(3)侧接收第二光学信号,第一光学收发器(1)停止切换第一光学信号的波长。(The present optical communication system shortens the time required to set the wavelength between optical transceivers at the time of starting up the system or at the time of replacing or newly adding an optical transceiver, and reduces the types of optical transceivers prepared for new addition or replacement. The first optical transceiver (1) outputs a first optical signal to an optical fiber (3) side while switching a wavelength of the first optical signal, the optical fiber (3) side being a medium serving as a single-core bidirectional communication for carrying a second optical transceiver (2) opposite to the first optical transceiver (1). When the wavelength of the first optical signal becomes a receivable wavelength, the second optical transceiver (2) recognizes the wavelength of the received first optical signal and outputs a second optical signal having a wavelength determined based on the recognition result to the optical fiber (3) side. Once the first optical transceiver (1) receives the second optical signal from the optical fiber (3) side, the first optical transceiver (1) stops switching the wavelength of the first optical signal.)

1. An optical communication system comprising:

a first optical transceiver configured to output a first optical signal;

a second optical transceiver opposite the first optical transceiver and configured to output a second optical signal; and

an optical fiber serving as a medium for carrying single-fiber bi-directional communication between the first optical transceiver and the second optical transceiver, wherein,

the first optical transceiver outputs the first optical signal to the optical fiber while switching a wavelength of the first optical signal,

when the wavelength of the first optical signal is switched to a receivable wavelength, the second optical transceiver recognizes the wavelength of the received first optical signal and outputs an optical signal having a wavelength determined based on the recognition result as the second optical signal to the optical fiber, and

the first optical transceiver stops switching the wavelength of the first optical signal when the first optical transceiver receives the second optical signal from the optical fiber.

2. The optical communication system of claim 1,

the first optical transceiver outputs the first optical signal to the optical fiber, the first optical signal including information indicative of a wavelength of the first optical signal, an

The second optical transceiver identifies a wavelength of the received first optical signal based on the information.

3. The optical communication system according to claim 1 or 2, wherein the second optical transceiver includes a storage device for storing a correspondence between reception wavelengths and transmission wavelengths, and determines, as the wavelength of the second optical signal, a transmission wavelength corresponding to a reception wavelength matching the wavelength indicated by the identification result, based on the identification result and the correspondence.

4. The optical communication system according to claim 1 or 2,

in the event that the second optical signal is not successfully received from the optical fiber even after a predetermined number of wavelength switchings have been performed, the first optical transceiver stops outputting the first optical signal,

in the case where the second optical transceiver is connected after stopping outputting the first optical signal,

the connected second optical transceiver outputs the second optical signal to the optical fiber while switching a wavelength of the second optical signal,

when the wavelength of the second optical signal is switched to a receivable wavelength, the first optical transceiver recognizes the wavelength of the received second optical signal and outputs an optical signal having a wavelength determined based on the recognition result as the first optical signal to the optical fiber, and

the second optical transceiver stops switching the wavelength of the second optical signal when the second optical transceiver receives the first optical signal from the optical fiber.

5. The optical communication system of claim 4,

the second optical transceiver includes a storage device for storing a correspondence between reception wavelengths and transmission wavelengths, and determines, as the wavelength of the second optical signal, a transmission wavelength corresponding to a reception wavelength that matches the wavelength indicated by the identification result, based on the identification result and the correspondence, and

the first optical transceiver includes a storage device for storing the correspondence relationship, and determines, as the wavelength of the first optical signal, a transmission wavelength corresponding to a reception wavelength that matches the wavelength indicated by the identification result, based on the identification result and the correspondence relationship.

6. The optical communication system of any one of claims 1 to 5, further comprising a first multiplexer/demultiplexer comprising a transmit port and a receive port for connecting to the first optical transceiver and a second multiplexer/demultiplexer comprising a transmit port and a receive port for connecting to the second optical transceiver, wherein,

the optical fiber is arranged between the first multiplexer/demultiplexer and the second multiplexer/demultiplexer,

specifying respective wavelengths that can be transmitted from and received by the first optical transceiver according to the transmission port and the reception port of the first multiplexer/demultiplexer to which the first optical transceiver is connected, and

specifying respective wavelengths that can be transmitted from and received by the second optical transceiver according to the transmission port and the reception port of the second multiplexer/demultiplexer to which the second optical transceiver is connected.

7. The optical communication system of any one of claims 1 to 5, further comprising a first multiplexer/demultiplexer comprising a transmit/receive port for connecting to the first optical transceiver and a second multiplexer/demultiplexer comprising a transmit/receive port for connecting to the second optical transceiver, wherein,

the optical fiber is arranged between the first multiplexer/demultiplexer and the second multiplexer/demultiplexer,

specifying a wavelength that the first optical transceiver can transmit and receive according to the transmit/receive port of the first multiplexer/demultiplexer to which the first optical transceiver is connected, an

Specifying a wavelength that the second optical transceiver is capable of transmitting and receiving according to the transmit/receive port of the second multiplexer/demultiplexer to which the second optical transceiver is connected.

8. An optical transceiver, comprising:

an optical output device for outputting a first optical signal to an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver itself and another opposing optical transceiver;

control means for switching a wavelength of the first optical signal to be output by the optical output means; and

an optical input device for inputting a second optical signal from the optical fiber, the second optical signal having a wavelength pre-associated with a wavelength of the first optical signal and being output when the other optical transceiver receives the first optical signal,

wherein the control device stops switching the wavelength of the first optical signal when the second optical signal is received by the optical input device.

9. The optical transceiver of claim 8, wherein the optical output device outputs the first optical signal to the optical fiber, the first optical signal including information indicative of a wavelength of the first optical signal.

10. An optical transceiver, comprising:

an optical input device for inputting a first optical signal output while switching a wavelength of the first optical signal, the first optical signal being output from an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver itself and another optical transceiver opposite thereto;

control means for identifying a wavelength of the first optical signal successfully received by the optical input means and determining a transmission wavelength based on the identification result; and

an optical output device for outputting a second optical signal having the transmission wavelength determined by the control device to the optical fiber.

11. The optical transceiver of claim 10, wherein the control means identifies the wavelength of the first optical signal received from the other optical transceiver based on information included in the first optical signal.

12. The optical transceiver according to claim 10 or 11, wherein the control means includes storage means for storing a correspondence between reception wavelengths and transmission wavelengths, and determines, as the transmission wavelength of the second optical signal, a transmission wavelength corresponding to a reception wavelength that matches a wavelength indicated by the identification result, based on the identification result and the correspondence.

13. An optical transceiver, comprising:

an optical output device for outputting a first optical signal to an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver itself and another opposing optical transceiver;

control means for switching a wavelength of the first optical signal to be output by the optical output means; and

an optical input device for inputting a second optical signal from the optical fiber, the second optical signal having a wavelength pre-associated with a wavelength of the first optical signal and being output when the other optical transceiver receives the first optical signal, wherein,

the control means stops switching the wavelength of the first optical signal when the second optical signal is received by the optical input means,

the optical input device inputs a third optical signal output while switching a wavelength of the third optical signal from the optical fiber,

the control means identifies the wavelength of the third optical signal successfully received by the optical input means and determines a transmission wavelength based on the identification result,

the optical output device outputs a fourth optical signal having the transmission wavelength determined by the control device to the optical fiber,

the wavelength of the third optical signal receivable by the optical input device is the wavelength of the second optical signal, an

The wavelength of the fourth optical signal determined by the control device is the wavelength of the first optical signal that is receivable by the other optical transceiver.

14. The optical transceiver of claim 13,

the optical output device outputs the first optical signal to the optical fiber, the first optical signal including information indicative of a wavelength of the first optical signal, an

The control device identifies a wavelength of the third optical signal successfully received by the optical input device based on information included in the third optical signal.

15. The optical transceiver of claim 13 or 14,

the optical output device stops outputting the first optical signal even if the second optical signal is not successfully received from the optical fiber after performing the predetermined number of wavelength switching, an

In the case where the third optical signal is successfully received by the optical input device after the output of the first optical signal is stopped, the control device identifies a wavelength of the third optical signal successfully received by the optical input device.

16. The optical transceiver according to any one of claims 13 to 15, wherein the control means includes storage means for storing a correspondence between reception wavelengths and transmission wavelengths, and determines, as the wavelength of the fourth optical signal, a transmission wavelength corresponding to a reception wavelength that matches the wavelength indicated by the identification result, based on the identification result and the correspondence.

17. The optical transceiver of any one of claims 8-16,

the optical fiber being arranged between a first multiplexer/demultiplexer comprising a transmit port and a receive port for connection to the optical transceiver and a second multiplexer/demultiplexer comprising a transmit port and a receive port for connection to the other optical transceiver,

specifying respective wavelengths that can be transmitted from and received by the optical transceiver according to the transmission port and the reception port of the first multiplexer/demultiplexer to which the optical transceiver is connected, an

Specifying respective wavelengths that can be transmitted from and received by the other optical transceivers according to the transmission ports and the reception ports of the second multiplexer/demultiplexer to which the other optical transceivers are connected.

18. The optical transceiver of any one of claims 8-16,

the optical fiber being arranged between a first multiplexer/demultiplexer comprising transmit/receive ports for connection to the optical transceivers and a second multiplexer/demultiplexer comprising transmit/receive ports for connection to the other optical transceivers,

specifying a wavelength capable of being transmitted and received by the optical transceiver according to the transmission/reception port of the first multiplexer/demultiplexer to which the optical transceiver is connected, an

Specifying wavelengths that can be transmitted and received by the other optical transceivers according to the transmission/reception ports of the second multiplexer/demultiplexer to which the other optical transceivers are connected.

19. An optical communication method, comprising:

a first output step performed by a first optical transceiver, the first output step outputting a first optical signal to an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the first optical transceiver and an opposing second optical transceiver while switching a wavelength of the first optical signal;

a second output step performed by the second optical transceiver, the second output step identifying a wavelength of the received first optical signal when the wavelength of the first optical signal is switched to a receivable wavelength, and outputting a second optical signal having a wavelength determined based on a result of the identification to the optical fiber; and

a stopping step performed by the first optical transceiver when the first optical transceiver receives the second optical signal from the optical fiber, the stopping step stopping switching the wavelength of the first optical signal.

20. The optical communication method according to claim 19,

the first outputting step outputs the first optical signal to the optical fiber, the first optical signal including information indicating a wavelength of the first optical signal, an

The second outputting step identifies a wavelength of the received first optical signal based on the information.

21. The optical communication method according to claim 19 or 20, wherein the second output step determines, as the wavelength of the second optical signal, a transmission wavelength corresponding to a reception wavelength that matches the wavelength indicated by the identification result, based on the identification result and a correspondence between reception wavelengths and transmission wavelengths.

22. The optical communication method of claim 19 or 20, further comprising:

a stopping step performed by the first optical transceiver, the stopping step stopping outputting the first optical signal even if the second optical signal is not successfully received from the optical fiber after performing a predetermined number of wavelength switchings,

a third output step performed by the second optical transceiver in a case where the second optical transceiver is connected after stopping outputting the first optical signal, the third output step outputting the second optical signal to the optical fiber while switching a wavelength of the second optical signal;

a fourth output step performed by the first optical transceiver, the fourth output step identifying a wavelength of the received second optical signal when the wavelength of the second optical signal is switched to a receivable wavelength, and outputting an optical signal having a wavelength determined based on a result of the identification as the first optical signal to the optical fiber; and

a stopping step performed by the second optical transceiver when the second optical transceiver receives the first optical signal from the optical fiber, the stopping step stopping switching the wavelength of the second optical signal.

23. The optical communication method of claim 22,

the second output step determines, as the wavelength of the second optical signal, a transmission wavelength corresponding to a reception wavelength that matches the wavelength indicated by the identification result, based on the identification result and the correspondence between the reception wavelength and the transmission wavelength, and

the fourth outputting step determines, as the wavelength of the first optical signal, a transmission wavelength corresponding to a reception wavelength that matches the wavelength indicated by the identification result, based on the correspondence and the identification result.

24. The optical communication method according to any one of claims 19 to 23,

the optical fiber being arranged between a first multiplexer/demultiplexer comprising a transmit port and a receive port for connection to the first optical transceiver and a second multiplexer/demultiplexer comprising a transmit port and a receive port for connection to the second optical transceiver,

specifying respective wavelengths that can be transmitted from and received by the first optical transceiver according to the transmission port and the reception port of the first multiplexer/demultiplexer to which the first optical transceiver is connected, and

specifying respective wavelengths that can be transmitted from and received by the second optical transceiver according to the transmission port and the reception port of the second multiplexer/demultiplexer to which the second optical transceiver is connected.

25. The optical communication method according to any one of claims 19 to 23,

the optical fiber being arranged between a first multiplexer/demultiplexer comprising a transmit/receive port for connection to the first optical transceiver and a second multiplexer/demultiplexer comprising a transmit/receive port for connection to the second optical transceiver,

specifying a wavelength capable of being transmitted and received by the first optical transceiver according to the transmission/reception port of the first multiplexer/demultiplexer to which the first optical transceiver is connected, an

Specifying a wavelength that can be transmitted and received by the second optical transceiver according to the transmission/reception port of the second multiplexer/demultiplexer to which the second optical transceiver is connected.

26. A non-transitory computer-readable medium storing a program that causes a control computer provided in an optical transceiver to execute a process, the process comprising:

a switching step of switching a wavelength of a first optical signal to be output to an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver and another optical transceiver opposite thereto; and

a stopping step of stopping switching of a wavelength of the first optical signal when receiving a second optical signal having a wavelength pre-associated with a wavelength of the first optical signal and being output when the other optical transceiver receives the first optical signal.

27. The non-transitory computer readable medium of claim 26, wherein the switching step includes the step of including information in the first optical signal indicative of a wavelength of the first optical signal.

28. A non-transitory computer-readable medium storing a program that causes a control computer provided in an optical transceiver to execute a process, the process comprising:

an identifying step of identifying a wavelength of a first optical signal received when the first optical signal output while switching the wavelength of the first optical signal is received from an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver and another optical transceiver opposite thereto;

a determination step of determining a transmission wavelength based on the recognition result from the recognition step; and

a switching step of switching a wavelength of a second optical signal to be output to the optical fiber so that the wavelength of the second optical signal is the transmission wavelength determined in the determining step.

29. The non-transitory computer-readable medium of claim 28, wherein the identifying step identifies the wavelength of the first optical signal received from the other optical transceiver based on information included in the first optical signal.

30. The non-transitory computer-readable medium according to claim 28 or 29, wherein the determining step determines, as the transmission wavelength of the second optical signal, a transmission wavelength corresponding to a reception wavelength that matches a wavelength indicated by the identification result, based on a correspondence between reception wavelengths and transmission wavelengths and the identification result.

31. A non-transitory computer-readable medium storing a program that causes a control computer provided in an optical transceiver to execute a process, the process comprising:

a first switching step of switching a wavelength of a first optical signal to be output to an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver and another optical transceiver opposite thereto;

a stopping step of stopping switching of a wavelength of the first optical signal when receiving a second optical signal having a wavelength pre-associated with a wavelength of the first optical signal and being output when the other optical transceiver receives the first optical signal;

an identifying step of identifying a wavelength of a received third optical signal when the third optical signal output while switching the wavelength of the third optical signal is received from the optical fiber;

a determination step of determining a transmission wavelength based on the recognition result from the recognition step; and

a second switching step of switching a wavelength of a fourth optical signal to be output to the optical fiber so that the wavelength of the fourth optical signal is the transmission wavelength determined in the determining step, wherein,

the wavelength of the third optical signal receivable from the optical fiber is the wavelength of the second optical signal, an

The wavelength of the fourth optical signal determined in the determining step is a wavelength of the first optical signal receivable by the other optical transceiver.

32. The non-transitory computer-readable medium of claim 31,

the first switching step comprises the step of including information indicative of the wavelength of the first optical signal in the first optical signal, and

the identifying step identifies a wavelength of the third optical signal received from the other optical transceiver based on information included in the third optical signal.

33. The non-transitory computer-readable medium of claim 31 or 32,

the first switching step includes a stopping step of stopping outputting the first optical signal even if the second optical signal is not successfully received from the optical fiber after the predetermined number of wavelength switching is performed, and

in the case where the third optical signal is successfully received from the optical fiber after the output of the first optical signal is stopped, the identifying step identifies a wavelength of the successfully received third optical signal.

34. The non-transitory computer-readable medium according to any one of claims 31 to 33, wherein the determining step determines, as the wavelength of the fourth optical signal, a transmission wavelength corresponding to a reception wavelength that matches the wavelength indicated by the identification result, based on the identification result and a correspondence between reception wavelengths and transmission wavelengths.

Technical Field

The present disclosure relates to an optical communication system, an optical transceiver, an optical communication method, and a program.

Background

Patent document 1 describes a technique used after starting up an operation in an optical communication system in which communication is performed between optical transceivers. With the optical transceiver described in patent document 1, a first optical signal is transmitted to an opposing optical transceiver through a single optical path, and a second optical signal is received from the opposing optical transceiver through the optical path. Further, with the optical transceiver described in patent document 1, the wavelength separation interval between the first optical signal and the second optical signal is controlled by acquiring first wavelength information included in the first optical signal indicating its wavelength, acquiring second wavelength information included in the second optical signal indicating its wavelength, and comparing the information.

On the other hand, for an optical communication system that performs communication between optical transceivers, it is necessary to establish optical communication when the system is started up and the optical transceivers are expanded or replaced. Further, the wavelength at which each optical transceiver can transmit and receive optical signals is determined by the wavelength selectively passed by the port of the connected multiplexer/demultiplexer. Therefore, in order to establish communication between the opposing optical transceivers, it is necessary to set an appropriate output wavelength according to the port to which each transceiver is connected.

Patent documents 2 and 3 describe wavelength tuning techniques for setting an appropriate output wavelength in an optical transceiver. With the technique described in patent document 2, LOSs of signal (LOS) information is exchanged between a first station having a plurality of fixed wavelength optical transceivers and a second station having a plurality of tunable wavelength optical transceivers, and the second station adjusts the wavelength of signal light to be output. The LOS information is superimposed as a low-frequency component on the signal light to be output through the first station. In the technique described in patent document 2, in the case where the wavelength of the signal light from the second station is not appropriate (when there is a reception load), the first station transmits LOS information to the second station, and the second station continues to switch the wavelength while receiving LOS information from the first station. Then, in the case of switching the wavelength of the signal light from the second station to a specific channel (when the signal becomes receivable), the first station stops outputting the LOS information, and when the LOS information is no longer received from the first station, the second station ends the wavelength switching control.

Patent document 3 describes a technique for establishing a channel between an Optical Line Terminal (OLT) and an Optical Network Terminal (ONT) of a Passive Optical Network (PON). With the technique described in patent document 3, wavelength adjustment is performed in two terminal stations of the OLT and the ONT. Specifically, the ONT outputs an optical signal of a certain wavelength to the OLT, and in the case of successfully receiving a response signal from the OLT within a first predetermined time, the ONT ends the control, whereas in the case of not receiving the response signal, the ONT switches the wavelength and outputs the optical signal to the OLT again. If the OLT successfully receives the optical signal from the ONT, the OLT outputs a response signal of a certain wavelength to the ONU, and in the case where the optical signal from the ONT is successfully received within the second predetermined time, the OLT ends the control, whereas in the case where the optical signal is not received, the OLT switches the wavelength and outputs the optical signal to the ONT again.

Reference list

Patent document

Patent document 1: PCT International published Japanese published translation No.2017-504224

Patent document 2: U.S. Pat. No. US9692547B2

Patent document 3: U.S. Pat. No. US9917671B2

Disclosure of Invention

Solves the technical problem

As described above, with the technique described in patent document 2, the setting of the wavelength is performed only by the optical transceiver of one (single-sided) terminal station, while the optical transceiver of the other terminal station is assumed to be set so that the output wavelength is fixed. Therefore, in the technique described in patent document 2, when it is necessary to replace a certain optical transceiver of another terminal station, it is necessary to prepare an optical transceiver dedicated to a fixed wavelength of the certain optical transceiver, which leads to higher system management cost.

Further, with the technique described in patent document 3, since scanning for sequentially switching wavelengths is performed in two terminal stations, it takes much time to set appropriate wavelengths in the two terminal stations, resulting in higher system management cost.

Therefore, in order to reduce the management cost in an optical communication system, it is desirable to reduce the time taken to set a wavelength and to reduce the type of optical transceiver to be prepared for replacement or expansion.

The present disclosure aims to provide an optical communication system, an optical transceiver, an optical communication method, and a program that solve the above-described problems. The above problems are to reduce the time taken to set the wavelength between optical transceivers during system startup or when expanding or replacing the optical transceivers, and to reduce the types of optical transceivers to be prepared for expansion or replacement in an optical communication system.

Technical scheme for solving problems

An optical communication system according to a first aspect of the present disclosure is provided with:

a first optical transceiver configured to output a first optical signal;

a second optical transceiver opposite the first optical transceiver and configured to output a second optical signal; and

an optical fiber serving as a medium for carrying single-fiber bidirectional communications between a first optical transceiver and a second optical transceiver, wherein,

while switching the wavelength of the first optical signal, the first optical transceiver outputs the first optical signal to the optical fiber,

when the wavelength of the first optical signal is switched to a receivable wavelength, the second optical transceiver recognizes the wavelength of the received first optical signal and outputs an optical signal having a wavelength determined based on the recognition result as a second optical signal to the optical fiber, and

the first optical transceiver stops switching the wavelength of the first optical signal when the first optical transceiver receives the second optical signal from the optical fiber.

An optical transceiver according to a second aspect of the present disclosure is provided with:

an optical output unit configured to output the first optical signal to an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver itself and the other optical transceiver as opposed;

a control unit configured to switch a wavelength of a first optical signal to be output by the optical output unit; and

an optical input unit configured to input a second optical signal from the optical fiber, the second optical signal having a wavelength pre-associated with a wavelength of the first optical signal and being output when the other optical transceiver receives the first optical signal,

wherein the control unit stops switching the wavelength of the first optical signal when the second optical signal is received by the optical input unit.

An optical transceiver according to a third aspect of the present disclosure is provided with:

an optical input unit configured to input a first optical signal output while switching a wavelength of the first optical signal, the first optical signal being output from an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver itself and the other optical transceiver as opposed;

a control unit configured to identify a wavelength of the first optical signal successfully received by the optical input unit, and determine a transmission wavelength based on the identification result; and

an optical output unit configured to output a second optical signal having the transmission wavelength determined by the control unit to the optical fiber.

An optical transceiver according to a fourth aspect of the present disclosure is provided with:

an optical output unit configured to output the first optical signal to an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver itself and the other optical transceiver as opposed;

a control unit configured to switch a wavelength of a first optical signal to be output by the optical output unit; and

an optical input unit configured to input a second optical signal from the optical fiber, the second optical signal having a wavelength pre-associated with a wavelength of the first optical signal and being output when the other optical transceiver receives the first optical signal, wherein,

when the second optical signal is received by the optical input unit, the control unit stops switching the wavelength of the first optical signal,

the optical input unit inputs a third optical signal output while switching the wavelength of the third optical signal from the optical fiber,

the control unit identifies the wavelength of the third optical signal successfully received by the optical input unit, and determines a transmission wavelength based on the identification result,

the optical output unit outputs a fourth optical signal having the transmission wavelength determined by the control unit to the optical fiber,

the wavelength of the third optical signal that the optical input unit can receive is the wavelength of the second optical signal, an

The wavelength of the fourth optical signal determined by the control unit is the wavelength of the first optical signal that the other optical transceiver is capable of receiving.

An optical communication method according to a fifth aspect of the present disclosure includes:

a first output step performed by the first optical transceiver, the first output step outputting the first optical signal to an optical fiber while switching a wavelength of the first optical signal, the optical fiber serving as a medium for carrying single-fiber bidirectional communication between the first optical transceiver and an opposing second optical transceiver;

a second output step performed by the second optical transceiver, the second output step identifying a wavelength of the received first optical signal when the wavelength of the first optical signal is switched to a receivable wavelength, and outputting a second optical signal having a wavelength determined based on the identification result to the optical fiber; and

a stopping step performed by the first optical transceiver when the first optical transceiver receives the second optical signal from the optical fiber, the stopping step stopping switching the wavelength of the first optical signal.

A program according to a sixth aspect of the present disclosure is a program that causes a control computer provided in an optical transceiver to execute processes including:

a switching step of switching a wavelength of a first optical signal to be output to an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver and the other optical transceiver as opposed; and

a stopping step of stopping switching of the wavelength of the first optical signal when receiving a second optical signal which has a wavelength previously associated with the wavelength of the first optical signal and is output when the other optical transceiver receives the first optical signal.

A program according to a seventh aspect of the present disclosure is a program that causes a control computer provided in an optical transceiver to execute processes including:

an identifying step of identifying a wavelength of a received first optical signal when the first optical signal output while switching the wavelength of the first optical signal is received from an optical fiber serving as a medium for carrying single-fiber bidirectional communication between an optical transceiver and another optical transceiver opposite thereto;

a determination step of determining a transmission wavelength based on the recognition result from the recognition step; and

a switching step of switching a wavelength of the second optical signal to be output to the optical fiber so that the wavelength of the second optical signal is the transmission wavelength determined in the determining step.

A program according to an eighth aspect of the present disclosure is a program that causes a control computer provided in an optical transceiver to execute processes including:

a first switching step of switching a wavelength of a first optical signal to be output to an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver and the other optical transceiver as opposed;

a stopping step of stopping switching of the wavelength of the first optical signal when receiving a second optical signal which has a wavelength previously associated with the wavelength of the first optical signal and is output when the other optical transceiver receives the first optical signal;

an identifying step of identifying, when a third optical signal output while switching a wavelength of the third optical signal is received from the optical fiber, the wavelength of the received third optical signal;

a determination step of determining a transmission wavelength based on the recognition result from the recognition step; and

a second switching step of switching a wavelength of a fourth optical signal to be output to the optical fiber so that the wavelength of the fourth optical signal is the transmission wavelength determined in the determining step, wherein,

the wavelength of the third optical signal receivable from the optical fiber is the wavelength of the second optical signal, an

The wavelength of the fourth optical signal determined in the determining step is a wavelength of the first optical signal receivable by the other optical transceiver.

Advantageous effects of the invention

According to the present disclosure, an optical communication system, an optical transceiver, an optical communication method, and a program that solve the above-described problems can be provided. In other words, according to the present disclosure, it is possible to reduce the time taken to set wavelengths between optical transceivers during system startup or when expanding or replacing the optical transceivers, and to reduce the types of optical transceivers to be prepared for expansion or replacement in an optical communication system.

Drawings

Fig. 1 is a schematic diagram showing an exemplary configuration of an optical communication system according to a first exemplary embodiment.

Fig. 2 is a block diagram illustrating an exemplary configuration of the optical communication system in fig. 1.

Fig. 3 is a flowchart for explaining an example of wavelength setting processing in the optical communication system according to the first exemplary embodiment.

Fig. 4 is a block diagram showing an exemplary configuration of an optical communication system according to the second exemplary embodiment.

Fig. 5 is a schematic diagram showing an example of a correspondence table stored in an optical transceiver of the optical communication system of fig. 4.

Fig. 6 is a flowchart for explaining an example of wavelength setting processing in the optical communication system according to the second exemplary embodiment.

Fig. 7 is a block diagram showing an exemplary configuration of an optical communication system according to the third exemplary embodiment.

Fig. 8 is a block diagram showing an exemplary configuration of an optical communication system according to the third exemplary embodiment.

Fig. 9 is a schematic diagram showing an example of a hardware configuration of a part of an optical transceiver.

Detailed Description

Exemplary embodiments are described below with reference to the accompanying drawings. Note that, in the exemplary embodiment, the same or similar elements may be denoted by the same reference numerals, and repeated description of these elements may be omitted in some cases.

< first exemplary embodiment >

An optical communication system according to a first exemplary embodiment is described below with reference to fig. 1 to 3. Fig. 1 is a schematic diagram showing an exemplary configuration of an optical communication system according to a first exemplary embodiment.

As shown in fig. 1, an optical communication system according to the present exemplary embodiment (hereinafter referred to as the present system) is provided with a first optical transceiver 1, a second optical transceiver 2, and an optical fiber 3, and optical communication occurs between the first optical transceiver 1 and the second optical transceiver 2 which are opposed to each other.

The first optical transceiver 1 outputs a first optical signal. The second optical transceiver 2 is opposite to the first optical transceiver 1 and outputs a second optical signal. The optical fiber 3 is a medium for carrying single-fiber bidirectional communication between the first optical transceiver 1 and the second optical transceiver 2. In other words, the present system includes a portion in which the first optical transceiver 1 and the second optical transceiver 2 are connected by a single optical fiber 3 serving as a single optical path. The first optical transceiver 1 and the second optical transceiver 2 may function as a first terminal station-side optical transceiver and a second terminal station-side optical transceiver, respectively, and the two terminal stations are connected by an optical fiber 3.

Fig. 1 shows an example in which there are one set of a first optical transceiver 1 and a second optical transceiver 2, but the present system may include a plurality of sets (pairs) of a first terminal station-side optical transceiver and a second terminal station-side optical transceiver. Note that such a situation may arise where half of the groups are temporarily unavailable, such as when expanding or replacing an optical transceiver.

The plurality of groups includes a portion in which the optical transceivers in each group are connected by the above-described single optical fiber 3. For the optical communication of this portion, a Wavelength Division Multiplexing (WDM) transmission system is employed. In other words, the system comprises a WDM transmission network that performs single-fiber bidirectional communication. For example, WDM communication can be performed by providing a first multiplexer/demultiplexer and a second multiplexer/demultiplexer on the first terminal station side and the second terminal station side, respectively, and connecting the two multiplexers/demultiplexers through a single optical fiber 3.

In an optical communication system such as the present system, the wavelength at which each optical transceiver can transmit and receive optical signals can be determined by the wavelength selectively passed by the port of the connected multiplexer/demultiplexer. As an example, the following describes a case where the ports to which the first optical transceiver 1 and the second optical transceiver 2 are connected pass through λ 1 and λ 2, respectively. In this case, when the first optical transceiver 1 outputs an optical signal of the wavelength λ 1 as a first optical signal and the opposite second optical transceiver 2 outputs an optical signal of the wavelength λ 2 as a second optical signal, optical communication can be performed between the first optical transceiver 1 and the second optical transceiver 2. Note that in the present exemplary embodiment and the exemplary embodiments described later, wavelengths may also be used to represent a range of wavelengths, which may be referred to as a wavelength band.

Further, in order to establish optical communication between the opposing optical transceivers at the operation start-up stage as described above, it is necessary to set an appropriate wavelength in each optical transceiver. Here, the operation start-up phase refers to a situation such as when the system is started up and the optical transceiver is replaced or expanded. Here, the system start refers to the start of the system, and may include a restart.

In order to set the wavelength as above, the following control is performed in the present system.

First, the first optical transceiver 1 outputs a first optical signal to the optical fiber 3 while switching the wavelength. With this arrangement, the first optical transceiver 1 scans which wavelengths are output to the optical fibre 3. Meanwhile, the second optical transceiver 2 cannot receive the first optical signal until a receivable wavelength is set.

When the wavelength of the first optical signal is switched to a receivable wavelength (for example, the wavelength λ 1), the second optical transceiver 2 identifies the wavelength of the received first optical signal. The second optical transceiver 2 outputs an optical signal having a wavelength (for example, wavelength λ 2) determined based on the recognition result as a second optical signal to the optical fiber 3. Further, when the first optical transceiver 1 receives the second optical signal (the optical signal of the wavelength λ 2 in the above example) from the optical fiber 3, the first optical transceiver 1 stops switching the wavelength of the first optical signal. It is clear that the first optical transceiver 1 and the second optical transceiver 2 may adopt an opposite configuration, but may also be configured such that each optical transceiver is provided with two controls described as being controlled by each optical transceiver.

A more specific exemplary configuration of each optical transceiver is described below with reference to fig. 2. Fig. 2 is a block diagram illustrating an exemplary configuration of the optical communication system in fig. 1.

As shown in fig. 2, the first optical transceiver 1 may be provided with a control unit 1a, an optical output unit 1b, and an optical input unit 1 c. The optical output unit 1b outputs the first optical signal to the optical fiber 3, the optical fiber 3 serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver itself and the other opposing optical transceiver (here, the second optical transceiver 2). The optical output unit 1b transmits an optical signal, and thus may also be referred to as a transmission unit. The optical output unit 1b may be configured to convert an electric signal representing information to be transmitted into an optical signal (first optical signal), and output the optical signal.

The control unit 1a switches the wavelength of the first optical signal to be output through the optical output unit 1 b. The control unit 1a may be regarded as a component controlling the first optical transceiver 1 as a whole, including such switching control. For example, the control unit 1a may be realized by a component as a whole such as a Central Processing Unit (CPU), a memory serving as a work space, a nonvolatile storage device storing a program for controlling the first optical transceiver 1. In other words, the control unit 1a may comprise a control computer incorporating a program in an executable manner. Furthermore, the control unit 1a may also be implemented by, for example, an integrated circuit.

The optical input unit 1c inputs a second optical signal from the optical fiber 3, the second optical signal having a wavelength previously associated with the wavelength of the first optical signal and being output when the other optical transceiver (here, the second optical transceiver 2) receives the first optical signal. An example of association will be described in a second exemplary embodiment. The optical input unit 1c receives an optical signal and may therefore also be referred to as a receiving unit. When the second optical signal is received through the optical input unit 1c, the control unit 1a stops switching the wavelength of the first optical signal. The optical input unit 1c may be configured to receive information by inputting a second optical signal and converting the second optical signal into an electrical signal.

The program built in the above-described control unit 1a causes the control computer to execute the following first switching step and stopping step. The first switching step switches the wavelength of the first optical signal output to the optical fiber 3. The stopping step stops switching the wavelength of the first optical signal when receiving the second optical signal having a wavelength previously associated with the wavelength of the first optical signal and output when the second optical transceiver 2 receives the first optical signal.

As shown in fig. 2, the second optical transceiver 2 may be provided with a control unit 2a, an optical output unit 2b, and an optical input unit 2 c. The optical input unit 2c inputs a first optical signal output from the optical fiber 3 at the switching wavelength, and the optical fiber 3 serves as a medium for carrying single-fiber bidirectional communication between the optical transceiver itself and the other opposing optical transceiver (here, the first optical transceiver 1). The optical input unit 2c receives an optical signal and may therefore also be referred to as a receiving unit. The optical input unit 2c may be configured to receive information by inputting a first optical signal and converting the first optical signal into an electrical signal.

The control unit 2a identifies the wavelength of the first optical signal successfully received through the optical input unit 2c, and determines the transmission wavelength based on the identification result. The control unit 2a can be regarded as a component controlling the second optical transceiver 2 as a whole, which includes such identification and determination control. The control unit 2a may be realized by, for example, components such as a CPU, a memory serving as a work space, a nonvolatile storage device storing a program for controlling the second optical transceiver 2 as a whole. In other words, the control unit 2a may comprise a control computer incorporating a program in an executable manner. Furthermore, the control unit 2a may also be implemented by, for example, an integrated circuit.

The optical output unit 2b outputs a second optical signal having the transmission wavelength determined by the control unit 2a to the optical fiber 3. The optical output unit 2b transmits an optical signal, and thus may also be referred to as a transmission unit. The optical output unit 2b may be configured to convert an electric signal representing information to be transmitted into an optical signal (second optical signal), and output the optical signal.

The program built in the above-described control unit 1a causes the control computer to execute the following identification step, determination step, and second switching step. When the first optical signal output at the time of switching the wavelength is received from the optical fiber 3, the identifying step identifies the wavelength of the received first optical signal. The determining step determines the transmission wavelength based on the recognition result from the recognizing step. The second switching step switches the wavelength of the second optical signal to be output to the optical fiber 3 to the transmission wavelength determined in the determining step.

An example of the wavelength setting process in the optical communication system according to the present exemplary embodiment is described below with reference to fig. 3. Fig. 3 is a flowchart for explaining an example of the wavelength setting process.

First, when the first optical transceiver 1 is connected, the first optical transceiver 1 selects one wavelength from among a plurality of wavelengths, and outputs a first optical signal to the optical fiber 3 while continuously switching to the selected wavelength (step S1). As a result of the wavelength switching (step S2, yes), when the wavelength of the first optical signal becomes a specific wavelength (herein designated as λ 1), the first optical signal can be received by the second optical transceiver 2. Therefore, at this time, the second optical transceiver 2 receives the first optical signal from the optical fiber 3 (step S3).

The second optical transceiver 2 recognizes the wavelength of the first optical signal, determines the wavelength of the second optical signal that the second optical transceiver 2 itself should output (step S4), and outputs the second optical signal having the determined wavelength to the optical fiber 3 (step S5). The first optical transceiver 1 receives the second optical signal (step S6), thereby stopping switching the wavelength (locking the wavelength at λ 1) (step S7).

As described above, the present system has a wavelength control mechanism that can specify which wavelengths each optical transceiver should output, while still allowing for variable wavelengths in the optical transceivers at any opposing end station in the WDM transmission network to establish communications at the appropriate wavelength.

According to this configuration, in the present system, it is possible to reduce the time taken to set the wavelength between the optical transceivers during system startup or when the optical transceivers are expanded or replaced, and to reduce the types of optical transceivers to be prepared for expansion or replacement. Therefore, in the present system, the management cost of the system can be reduced.

This effect is described in detail below. First, in order to reduce the management cost of the optical transceiver, it is desirable to adopt a configuration in which: allowing a variable wavelength optical transceiver to be employed in any of the terminal stations and reducing the types of optical transceivers to be prepared. In this regard, in the present exemplary embodiment, the first optical transceiver 1 has a variable wavelength configuration that outputs an optical signal while switching wavelengths, and likewise, the second optical transceiver 2 has a variable wavelength configuration that determines a transmission wavelength based on a wavelength that is successfully received. In this manner, each optical transceiver in the present system is able to selectively switch wavelengths to output optical signals, and is able to determine (identify) ports that are undetermined due to unknown wavelengths during startup in each optical transceiver. With this arrangement, in the present system, wavelength adjustment (wavelength tuning) can be performed to set an appropriate wavelength according to the connected port without presetting the wavelength that each optical transceiver should output in the two terminal stations. Thus, during expansion, replacement, etc., the appropriate wavelength may be automatically set by simply connecting each optical transceiver to a port, e.g., without having a worker intentionally decide which port each optical transceiver should be connected to.

Further, in the case where both the terminal stations employ optical transceivers having a variable wavelength configuration, it is desirable to reduce the man-hours and time for setting appropriate wavelengths in both the terminal stations. In this regard, in the present exemplary embodiment, since the opposing optical transceiver recognizes the received wavelength and decides the wavelength that the optical transceiver itself should output, wavelength tuning can be performed without performing wavelength switching, and the time taken to set the wavelength for the system as a whole can be reduced. In other words, in the present exemplary embodiment, the wavelength can be set in a shorter time than when scanning is performed in two terminal stations.

Further, in communication (mobile fronthaul communication) between an antenna station and a terminal station in a 5G network, for example, WDM transmission is employed, and an optical transceiver that outputs an optical signal is provided in each base station. Optical signals are transmitted and received between the opposing optical transceivers over a single optical fiber 3 (single fiber bi-directional communication). The present exemplary embodiment can also be applied to such mobile fronthaul communication.

An optical transceiver having a configuration described as two controls controlled by each optical transceiver will be briefly described herein. Note that although an example is described in which the first optical transceiver 1 is configured by such a configuration, a similar configuration may be employed in the second optical transceiver 2. The first optical transceiver 1 in this configuration can be obtained by causing the control unit 1a, the optical output unit 1b, and the optical input unit 1c to additionally perform control in the control unit 2a, the optical output unit 2b, and the optical input unit 2c, respectively (to additionally have the functions of the units 2a, 2b, and 2 c).

First, as described above, the control in the case of newly connecting the first optical transceiver 1 is as follows. That is, the optical output unit 1b outputs the first optical signal to the optical fiber 3, and the control unit 1a switches the wavelength of the first optical signal to be output through the optical output unit 1 b. The optical input unit 1c inputs a second optical signal from the optical fiber 3, the second optical signal having a wavelength previously associated with the wavelength of the first optical signal and being output when the other optical transceiver (here, the second optical transceiver 2) receives the first optical signal. When the second optical signal is received through the optical input unit 1c, the control unit 1a stops switching the wavelength of the first optical signal.

The control in the case where the first optical transceiver 1 has been connected is described below. The control is as follows, as described by the control by the second optical transceiver 2. That is, the optical input unit 1c inputs the third optical signal output from the optical fiber 3 at the switching wavelength. The control unit 1a identifies the wavelength of the third optical signal successfully received through the optical input unit 1c, and determines the transmission wavelength based on the identification result. The optical output unit 1b outputs a fourth optical signal having the transmission wavelength determined by the control unit 1a to the optical fiber 3.

In the description herein, the name of the optical signal has been changed, but the wavelength of the third optical signal successfully received through the optical input unit 1c is the wavelength of the second optical signal, and the wavelength of the fourth optical signal determined through the control unit 1a is the wavelength of the first optical signal successfully received through the other optical transceiver as described above.

The control computer provided in the first optical transceiver 1 by such a configuration can incorporate the program in an executable manner as follows. In other words, the program causes the control computer to execute the first switching step, the stopping step, the identifying step, the determining step, and the second switching step described above. Note that the identifying step, the determining step, and the second switching step are substantially similar to the previously described steps except that the name of the optical signal has changed.

By adopting such a configuration, a common configuration can be obtained for the optical transceivers of both the first terminal station side and the second terminal station side. Further, an optical transceiver having both functions described herein can also be applied to the examples described in the following exemplary embodiments.

Here, a supplementary description is given of an optical communication method in the present system. As described in the wavelength setting process, the present system can execute an optical communication method including a first output step, a second output step, and a stop step as follows. In a first output step, the first optical transceiver 1 outputs a first optical signal to the optical fiber 3 while switching the wavelength, the optical fiber 3 acting as a medium for carrying single-fiber bidirectional communication between the first optical transceiver 1 and the opposing second optical transceiver 2. In the second output step, when the wavelength of the first optical signal is switched to a receivable wavelength, the second optical transceiver 2 identifies the wavelength of the received first optical signal and outputs a second optical signal having a wavelength determined based on the identification result to the optical fiber 3. In the stop step, when the first optical transceiver 1 receives the second optical signal from the optical fiber 3, the first optical transceiver 1 stops switching the wavelength of the first optical signal. Other examples are described above and may also be applied to examples described in the following exemplary embodiments.

< second exemplary embodiment >

In the second exemplary embodiment, differences from the first exemplary embodiment are described mainly with reference to fig. 4 to 6, but various examples described in the first exemplary embodiment are available. Fig. 4 is a block diagram showing an exemplary configuration of an optical communication system according to a second exemplary embodiment, and fig. 5 is a diagram showing an example of a correspondence table stored in an optical transceiver of the optical communication system of fig. 4.

As shown in fig. 3, in the optical communication system according to the present exemplary embodiment (hereinafter referred to as the present system), a first terminal station 10 and a second terminal station 20 are connected by a single optical fiber 3. Further, the first terminal station 10 is provided with n (where n is a positive integer) optical transceivers 11-1 to 11-n, and a first multiplexer/demultiplexer 12 connected to the optical transceivers. The second terminal station 20 is provided with n optical transceivers 21-1 to 21-n, and a second multiplexer/demultiplexer 22 connected to the optical transceivers. Hereinafter, the optical transceivers 11-1 to 11-n are designated as the optical transceiver 11 when they are not separately distinguished, and the optical transceivers 21-1 to 21-n are designated as the optical transceiver 21 when they are not separately distinguished.

The optical fiber 3 is arranged between the first multiplexer/demultiplexer 12 and the second multiplexer/demultiplexer 22. For example, both the first multiplexer/demultiplexer 12 and the second multiplexer/demultiplexer 22 may be configured using an Arrayed Waveguide Grating (AWG). In addition, optical signals are transmitted and received between the opposing optical transceivers 11 and 21 through the first multiplexer/demultiplexer 12 and the second multiplexer/demultiplexer 22. The optical signal output from each optical transceiver 11 or 21 is multiplexed, transmitted through the optical fiber 3 of the optical fiber network, demultiplexed by the multiplexer/demultiplexer of the opposite station, and then received by the opposite optical transceiver 21 or 11. The same applies to communication in the opposite direction.

Further, a case is described in which the optical transceiver 11-1 is an optical transceiver newly connected on the first terminal station 10 side due to replacement or expansion, and the connected optical transceiver 21-n is an optical transceiver on the second terminal station 20 side opposite to the first optical transceiver 11-1. In other words, a case is described in which the first optical transceiver 11-1 is newly connected in a state in which the optical transceivers 11-2 to 11-n have been connected to the respective ports of the first multiplexer/demultiplexer 12 and the optical transceivers 21-1 to 21-n have been connected to the respective ports of the second multiplexer/demultiplexer 22. Note that even in the case where a plurality of optical transceivers are newly connected at the same time, if the opposite optical transceiver is already connected, the following description can be similarly referred to.

For example, the first optical transceiver 11-1 may be configured similarly to the first optical transceiver 1 in FIG. 2, and the second optical transceiver 21-n may be configured similarly to the second optical transceiver 2 in FIG. 2, although both functions may be included in either configuration. The same applies to the other optical transceivers 11-2 to 11-n and 21-1 to 21- (n-1). In other words, with respect to these optical transceivers, one of the optical transceiver on the first terminal station 10 side or the opposite optical transceiver on the second terminal station 20 side may include the function of the first optical transceiver 1 in fig. 2, and the other may include the function of the second optical transceiver 2 in fig. 2. Furthermore, both functions may also be included in all optical transceivers.

The wavelength that the first optical transceiver 11-1 can transmit and receive is determined according to the port of the first multiplexer/demultiplexer 12 to which the first optical transceiver 11-1 is connected. Here, let λ 1 be a wavelength transmittable on a port of the first multiplexer/demultiplexer 12 to which the first optical transceiver 11-1 is connected (transmission wavelength, or in other words, output wavelength), and let λ 2 be a wavelength receivable on the port (reception wavelength, or in other words, input wavelength). In other words, it is assumed that the first multiplexer/demultiplexer 12 has a port in which an optical signal having a wavelength λ 1 can be input from the first optical transceiver 11-1, and in which an optical signal having a wavelength λ 2 can be output to the optical transceiver 11-1.

For example, the first optical transceiver 11-1 is configured to select a wavelength from among a plurality of wavelengths and output an optical signal while continuously switching the wavelength at predetermined intervals. As described above, it is assumed that wavelengths that can be input and output on each port of the first multiplexer/demultiplexer 12 are fixed and different from each other. Note that each port to which the other optical transceivers 11-2 to 11-n are connected is capable of transferring an optical signal by having a transmission wavelength and a reception wavelength different from λ 1 and λ 2 and different from each other.

The wavelengths that the second optical transceiver 21-n is capable of transmitting and receiving are determined according to the port of the second multiplexer/demultiplexer 22 to which the second optical transceiver 21-n is connected. A case is described herein in which the second optical transceiver 21-n is an optical transceiver that communicates oppositely to the first optical transceiver 11-1, so the transmission wavelength is λ 2 and the reception wavelength is λ 1. In other words, the second multiplexer/demultiplexer 22 has a port on which an optical signal with a wavelength λ 2 can be input from the second optical transceiver 21-n and on which an optical signal with a wavelength λ 1 can be output to the second optical transceiver 21-n. The wavelengths that can be input and output at each port of the second multiplexer/demultiplexer 22 are also assumed to be fixed and different from each other.

Thereafter, the second optical transceiver 21-n identifies the wavelength of the first optical signal input from the first optical transceiver 11-1, determines the wavelength that the second optical transceiver 21-n should output itself based on the identified wavelength, and outputs an optical signal (second optical signal) of the determined wavelength. Further, the first optical transceiver 11-1 receives the second optical signal and stops switching the wavelength (locking the wavelength to λ 1).

In the present exemplary embodiment, the first optical transceiver 11-1 may be configured to output a first optical signal including information (first information) indicating a wavelength of the first optical signal to the optical fiber 3. In the example of fig. 2, the optical output unit 1b outputs a first optical signal including first information to the optical fiber 3. For example, the first information may be included as header information of the first optical signal, and so on. In this way, in the present exemplary embodiment, the wavelength at the time of output can be included in the first optical signal.

The second optical transceiver 21-n opposite to the first optical transceiver 11-1 is capable of identifying the wavelength of the received first optical signal based on the first information and determining the wavelength based on the identification result. In the example of fig. 2, the control unit 2a identifies the wavelength of the first optical signal received from the first optical transceiver 11-1 based on information included in the first optical signal.

Further, the second optical transceiver 21-n preferably includes a storage unit that stores a correspondence between a reception wavelength (input wavelength) and a transmission wavelength (output wavelength). For example, the storage unit may be provided in the control unit 2a of fig. 2. Further, the correspondence may be stored as a table, such as the table 50 shown in fig. 5. Table 50 sets forth correspondences such as between λ 1-1 and λ 2-1 and between λ 1-2 and λ 2-2.

Further, based on the identification result and the correspondence, the second optical transceiver 21-n (such as the control unit 2a, for example) is configured to determine, as the wavelength of the second optical signal, the transmission wavelength corresponding to the reception wavelength that matches the wavelength indicated by the identification result.

An example of the wavelength setting process in the optical communication system according to the present exemplary embodiment is described below with reference to fig. 6. Fig. 6 is a flowchart for explaining an example of the wavelength setting process. Note that, since the time sequence is shown, the flow in fig. 6 is shown according to a labeling method different from that of fig. 3.

First, when the first optical transceiver 11-1 is connected to the first multiplexer/demultiplexer 12, the first optical transceiver 11-1 selects one wavelength from among a plurality of wavelengths and outputs a first optical signal including information indicating the selected wavelength (step S11). Next, the first optical transceiver 11-1 determines whether a second optical signal has been received from the opposing second optical transceiver 21-n (step S12), and if not (in the case of "no"), the first optical transceiver 11-1 returns to step S11 and selects the next wavelength (step S13). When the determination in step S12 is yes, the wavelength switching is stopped (wavelength is locked to λ 1-1) (step S13).

When the wavelength of the first optical signal becomes a specific wavelength (λ 1-1) due to switching the wavelength and outputting the first optical signal in step S11, the second optical transceiver 21-n can receive the first optical signal. Accordingly, the second optical transceiver 21-n determines whether the first optical signal has been received (step S21). In the case of yes at step S21, the second optical transceiver 21-n reads the wavelength (λ 1-1) from the information included in the first optical signal, and determines the wavelength (λ 2-1) previously associated with the read wavelength as the output wavelength with reference to the table 50 (step S22). Next, the second optical transceiver 21-n outputs a second optical signal having the determined wavelength (λ 2-1) (step S23).

As is apparent from the above description, according to the present exemplary embodiment, the effects of the first exemplary embodiment are exhibited, and furthermore, the received wavelength can be easily distinguished in the opposing second optical transceiver 21-n without depending on processing such as wavelength analysis. Further, in the present exemplary embodiment, the wavelength information is not transmitted to the opposite two sides, but the wavelength tuning can be performed at one side by using the wavelength information from the other side as a trigger. Further, according to the present exemplary embodiment, by storing the correspondence in advance, it is possible to appropriately set the wavelength regardless of which port of which terminal station the optical transceivers 11 and 21 are connected to.

The description of the above example assumes that each port in the first multiplexer/demultiplexer 12 and the second multiplexer/demultiplexer 22 is a transmission/reception port. One example of such a transmit/receive port is a Bidirectional Optical Subassembly (BOSA). Further, the description of the above example assumes that the multiplexer/demultiplexer and the optical transceiver are connected by a single optical fiber. In other words, it is assumed that the first multiplexer/demultiplexer 12 has a transmission/reception port for connecting to the first optical transceiver 11-1, and that the second multiplexer/demultiplexer 22 has a transmission/reception port for connecting to the second optical transceiver 21-n. In this case, as described above, the wavelengths that the first optical transceiver 11-1 can transmit and receive are specified according to the transmission/reception port of the first multiplexer/demultiplexer 12 to which the first optical transceiver 11-1 is connected. Further, the wavelengths that the second optical transceivers 21-n can transmit and receive are specified according to the transmission/reception ports of the second multiplexer/demultiplexer 22 to which the second optical transceivers 21-n are connected. The same applies to the other optical transceivers 11 and 21.

On the other hand, the transmission port and the reception port may be separately configured, and the multiplexer/demultiplexer and the optical transceiver may be connected by two optical fibers. For example, the transmit port may be a Transmitter Optical Subassembly (TOSA) and the receive port may be a Receiver Optical Subassembly (ROSA). In other words, the first multiplexer/demultiplexer 12 may have a transmission port and a reception port for connecting the first optical transceiver 11-1, and the second multiplexer/demultiplexer 22 may have a transmission port and a reception port for connecting the second optical transceiver 21-n. In this case, the respective wavelengths that can be transmitted from the first optical transceiver 11-1 and received by the first optical transceiver 11-1 are specified according to the transmission port and the reception port of the first multiplexer/demultiplexer 12 to which the first optical transceiver 11-1 is connected. Further, the respective wavelengths that can be transmitted from and received by the second optical transceivers 21-n are specified in accordance with the transmission ports and reception ports of the second multiplexer/demultiplexer 22 to which the second optical transceivers 21-n are connected. The same applies to the other optical transceivers 11 and 21.

< third exemplary embodiment >

In the third exemplary embodiment, differences from the second exemplary embodiment are described mainly with reference to fig. 7 and 8. However, the various examples described in the first and second exemplary embodiments are also applicable to the third exemplary embodiment where appropriate. Fig. 7 and 8 are block diagrams showing exemplary configurations of an optical communication system according to a third exemplary embodiment, in which fig. 7 is an example showing a case where no opposing optical transceiver exists, and fig. 8 is an example showing a point of time when an opposing optical transceiver is connected.

As shown in fig. 7, the present exemplary embodiment describes a case in which, when the first optical transceiver 11-1 is connected on the first terminal station 10 side, there is no opposing optical transceiver on the second terminal station 20 side.

The first optical transceiver 11-1 in the present exemplary embodiment stops outputting the first optical signal in the case where the second optical signal is not successfully received from the optical fiber 3 even after the predetermined number of wavelength switching is performed. In other words, of the two optical transceivers of the first terminal station 10 and the second terminal station 20 opposed to each other, the optical transceivers connected to the ports start scanning similar to that described above. An example of a situation is shown here where there are 10 sets of wavelengths, the predetermined number of times may be 10 cycles from λ 1-1 to λ 1-10, or a lesser number of times, such as 2 or 5, for example, or m cycles (where m is a positive integer). Further, in the case where the second optical signal is not successfully received, the first optical transceiver 11-1 enters a standby state, waiting until an optical transceiver opposite to the first optical transceiver 11-11 is connected in the second terminal station 20.

In such a standby state (i.e., after stopping the output of the first optical signal), as shown in fig. 8, if the second optical transceiver 21-n opposite to the first optical transceiver 11-1 in the standby state is connected, the following control is performed. That is, the connected second optical transceiver 21-n outputs the second optical signal to the optical fiber 3 while switching the wavelength of the second optical signal. Thereafter, when switching the wavelength of the second optical signal to a receivable wavelength, the first optical transceiver 11-1 identifies the wavelength of the received second optical signal, and outputs an optical signal having a wavelength determined based on the identification result to the optical fiber 3 as the first optical signal. Further, when the state shown in fig. 4 is reached, or in other words, when the second optical transceiver 21-n receives the first optical signal from the optical fiber 3, the second optical transceiver 21-n stops switching the wavelength of the second optical signal.

Further, in the present exemplary embodiment, the second optical transceiver 21-n also preferably includes a storage unit that stores the correspondence between the reception wavelength and the transmission wavelength. Further, the second optical transceiver 21-n preferably determines, as the wavelength of the second optical signal, the transmission wavelength corresponding to the reception wavelength that matches the wavelength indicated by the identification result, based on the identification result and the correspondence relationship. Further, in the present exemplary embodiment, the first optical transceiver 11-1 also preferably includes a storage unit that stores the correspondence relationship. Similarly, the first optical transceiver 11-1 also preferably determines, as the wavelength of the first optical signal, the transmission wavelength corresponding to the reception wavelength that matches the wavelength indicated by the identification result, based on the identification result and the correspondence stored in the storage unit.

As described above, according to the present exemplary embodiment, in addition to the effects provided by the first or second exemplary embodiment, even in the case where an optical transceiver is connected but an opposing optical transceiver is not connected at the same time, the optical transceiver can wait for connection and set the wavelength. Further, according to the present exemplary embodiment, by storing the correspondence in advance, it is possible to appropriately set the wavelength regardless of which port of which terminal station the optical transceivers 11 and 21 are connected to.

< other exemplary embodiments >

In the above-described exemplary embodiments, the functions of each unit of the optical transceiver are described, but it is sufficient for these functions to be implemented as the optical transceiver. Further, the above-described exemplary embodiments illustrate configuration examples of an optical communication system, but are not limited to the illustrated examples. Further, various examples described in the exemplary embodiments may be combined as appropriate.

Further, the optical transceiver according to an exemplary embodiment may have a hardware configuration as follows. Fig. 9 is a schematic diagram showing an example of a hardware configuration of a part of an optical transceiver according to an exemplary embodiment.

The optical transceiver 100 shown in fig. 9 includes a processor 101, a memory 102, and an interface 103. The interface 103 may be an interface associated with an optical output device and an optical input device, not shown. The functions of each unit described in the exemplary embodiment are realized by the processor 101 loading a program stored in the memory 102 and executing the program in cooperation with the interface 103. The program may be the program described in the exemplary embodiment.

In the above examples, the program may be stored and provided to the computer by using any type of non-transitory computer readable medium. Non-transitory computer readable media include any type of tangible storage media. Examples of non-transitory computer readable media include magnetic recording media (e.g., floppy disks, tapes, or hard disk drives) and magneto-optical recording media (e.g., magneto-optical disks). Other examples include optical disk-read only memory (CD-ROM), CD-R, and CD-R/W. Other examples include semiconductor memory (e.g., mask ROM, programmable ROM (prom), erasable prom (eprom), flash ROM, and Random Access Memory (RAM)). Further, the program may also be provided to the computer through any type of transitory computer-readable medium. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The transitory computer readable medium may provide the program to the computer through a wired communication channel such as a cable or an optical fiber or through a wireless communication channel.

Note that the present disclosure is not limited to the various exemplary embodiments described above, and may be appropriately modified within the scope not departing from the gist. Further, the present disclosure can be implemented by appropriately combining the respective exemplary embodiments.

All or a part of the foregoing exemplary embodiments may also be described as, but not limited to, the following supplementary notes.

< supplementary notes >

(supplementary notes 1)

An optical communication system comprising:

a first optical transceiver configured to output a first optical signal;

a second optical transceiver opposite the first optical transceiver and configured to output a second optical signal; and

an optical fiber serving as a medium for carrying single-fiber bidirectional communications between a first optical transceiver and a second optical transceiver, wherein,

while switching the wavelength of the first optical signal, the first optical transceiver outputs the first optical signal to the optical fiber,

when the wavelength of the first optical signal is switched to a receivable wavelength, the second optical transceiver recognizes the wavelength of the received first optical signal and outputs an optical signal having a wavelength determined based on the recognition result as a second optical signal to the optical fiber, and

the first optical transceiver stops switching the wavelength of the first optical signal when the first optical transceiver receives the second optical signal from the optical fiber.

(supplementary notes 2)

The optical communication system according to supplementary note 1, wherein,

the first optical transceiver outputs a first optical signal to the optical fiber, the first optical signal including information indicative of a wavelength of the first optical signal, an

The second optical transceiver identifies a wavelength of the received first optical signal based on the information.

(supplementary notes 3)

The optical communication system according to supplementary note 1 or 2, wherein the second optical transceiver includes a storage unit configured to store a correspondence between the reception wavelength and the transmission wavelength, and determines, as the wavelength of the second optical signal, the transmission wavelength corresponding to the reception wavelength that matches the wavelength indicated by the identification result, based on the identification result and the correspondence.

(supplementary notes 4)

The optical communication system according to supplementary note 1 or 2, wherein,

in the case where the second optical signal is not successfully received from the optical fiber even after the predetermined number of wavelength switching is performed, the first optical transceiver stops outputting the first optical signal,

in the case where the second optical transceiver is connected after stopping outputting the first optical signal,

while switching the wavelength of the second optical signal, the connected second optical transceiver outputs the second optical signal to the optical fiber,

when the wavelength of the second optical signal is switched to a receivable wavelength, the first optical transceiver recognizes the wavelength of the received second optical signal and outputs an optical signal having a wavelength determined based on the recognition result as a first optical signal to the optical fiber, and

the second optical transceiver stops switching the wavelength of the second optical signal when the second optical transceiver receives the first optical signal from the optical fiber.

(supplementary notes 5)

The optical communication system according to supplementary note 4, wherein,

the second optical transceiver includes a storage unit configured to store a correspondence between the reception wavelength and the transmission wavelength, and determines, as the wavelength of the second optical signal, the transmission wavelength corresponding to the reception wavelength that matches the wavelength indicated by the identification result, based on the identification result and the correspondence, and

the first optical transceiver includes a storage unit configured to store the correspondence relationship, and determines, as the wavelength of the first optical signal, a transmission wavelength corresponding to a reception wavelength that matches the wavelength indicated by the identification result, based on the identification result and the correspondence relationship.

(supplementary notes 6)

The optical communication system according to any one of supplementary notes 1 to 5, further comprising a first multiplexer/demultiplexer including a transmission port and a reception port for connecting to the first optical transceiver and a second multiplexer/demultiplexer including a transmission port and a reception port for connecting to the second optical transceiver, wherein,

the optical fiber is arranged between the first multiplexer/demultiplexer and the second multiplexer/demultiplexer,

specifying respective wavelengths capable of being transmitted from and received by the first optical transceiver according to a transmission port and a reception port of a first multiplexer/demultiplexer to which the first optical transceiver is connected, an

The respective wavelengths that can be transmitted from and received by the second optical transceiver are specified according to the transmission port and the reception port of the second multiplexer/demultiplexer to which the second optical transceiver is connected.

(supplementary notes 7)

The optical communication system according to any one of supplementary notes 1 to 5, further comprising a first multiplexer/demultiplexer including a transmission/reception port for connecting to the first optical transceiver and a second multiplexer/demultiplexer including a transmission/reception port for connecting to the second optical transceiver, wherein,

the optical fiber is arranged between the first multiplexer/demultiplexer and the second multiplexer/demultiplexer,

defining wavelengths that the first optical transceiver is capable of transmitting and receiving according to the transmit/receive ports of the first multiplexer/demultiplexer to which the first optical transceiver is connected, an

The wavelengths that the second optical transceiver can transmit and receive are specified according to the transmission/reception ports of the second multiplexer/demultiplexer to which the second optical transceiver is connected.

(supplementary notes 8)

An optical transceiver, comprising:

an optical output unit configured to output the first optical signal to an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver itself and the other optical transceiver as opposed;

a control unit configured to switch a wavelength of a first optical signal to be output by the optical output unit; and

an optical input unit configured to input a second optical signal from the optical fiber, the second optical signal having a wavelength pre-associated with a wavelength of the first optical signal and being output when the other optical transceiver receives the first optical signal,

wherein the control unit stops switching the wavelength of the first optical signal when the second optical signal is received by the optical input unit.

(supplementary notes 9)

The optical transceiver according to supplementary note 8, wherein the optical output unit outputs a first optical signal to the optical fiber, the first optical signal including information indicating a wavelength of the first optical signal.

(supplementary notes 10)

An optical transceiver, comprising:

an optical input unit configured to input a first optical signal output while switching a wavelength of the first optical signal, the first optical signal being output from an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver itself and the other optical transceiver as opposed;

a control unit configured to identify a wavelength of the first optical signal successfully received by the optical input unit, and determine a transmission wavelength based on the identification result; and

an optical output unit configured to output a second optical signal having the transmission wavelength determined by the control unit to the optical fiber.

(supplementary notes 11)

The optical transceiver according to supplementary note 10, wherein the control unit identifies the wavelength of the first optical signal received from the other optical transceiver based on information included in the first optical signal.

(supplementary notes 12)

The optical transceiver according to supplementary note 10 or 11, wherein the control unit includes a storage unit configured to store a correspondence between the reception wavelength and the transmission wavelength, and determines, as the transmission wavelength of the second optical signal, the transmission wavelength corresponding to the reception wavelength that matches the wavelength indicated by the identification result, based on the identification result and the correspondence.

(supplementary notes 13)

An optical transceiver, comprising:

an optical output unit configured to output the first optical signal to an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver itself and the other optical transceiver as opposed;

a control unit configured to switch a wavelength of a first optical signal to be output by the optical output unit; and

an optical input unit configured to input a second optical signal from the optical fiber, the second optical signal having a wavelength pre-associated with a wavelength of the first optical signal and being output when the other optical transceiver receives the first optical signal, wherein

When the second optical signal is received by the optical input unit, the control unit stops switching the wavelength of the first optical signal,

the optical input unit inputs a third optical signal output while switching the wavelength of the third optical signal from the optical fiber,

the control unit identifies the wavelength of the third optical signal successfully received by the optical input unit, and determines a transmission wavelength based on the identification result,

the optical output unit outputs a fourth optical signal having the transmission wavelength determined by the control unit to the optical fiber,

the wavelength of the third optical signal receivable by the optical input unit is the wavelength of the second optical signal, an

The wavelength of the fourth optical signal determined by the control unit is the wavelength of the first optical signal that can be received by the other optical transceiver.

(supplementary notes 14)

The optical transceiver according to supplementary note 13, wherein,

the optical output unit outputs a first optical signal to the optical fiber, the first optical signal including information indicating a wavelength of the first optical signal, an

The control unit identifies a wavelength of the third optical signal successfully received by the optical input unit based on information included in the third optical signal.

(supplementary notes 15)

The optical transceiver according to supplementary note 13 or 14, wherein,

in the case where the second optical signal is not successfully received from the optical fiber even after the predetermined number of wavelength switching is performed, the optical output unit stops outputting the first optical signal, an

After stopping outputting the first optical signal, in a case where the third optical signal is successfully received by the optical input unit, the control unit identifies a wavelength of the third optical signal successfully received by the optical input unit.

(supplementary notes 16)

The optical transceiver according to any one of supplementary notes 13 to 15, wherein the control unit includes a storage unit configured to store a correspondence between the reception wavelength and the transmission wavelength, and determines, as the wavelength of the fourth optical signal, the transmission wavelength corresponding to the reception wavelength that matches the wavelength indicated by the identification result, based on the identification result and the correspondence.

(supplementary notes 17)

The optical transceiver according to any one of supplementary notes 8 to 16, wherein

The optical fiber is arranged between a first multiplexer/demultiplexer comprising a transmit port and a receive port for connection to an optical transceiver and a second multiplexer/demultiplexer comprising a transmit port and a receive port for connection to other optical transceivers,

specifying respective wavelengths capable of being transmitted from and received by the optical transceiver according to a transmission port and a reception port of a first multiplexer/demultiplexer to which the optical transceiver is connected, an

The respective wavelengths that can be transmitted from and received by the other optical transceivers are specified according to the transmission ports and reception ports of the second multiplexer/demultiplexer to which the other optical transceivers are connected.

(supplementary notes 18)

The optical transceiver according to any one of supplementary notes 8 to 16, wherein,

the optical fiber is arranged between a first multiplexer/demultiplexer comprising transmit/receive ports for connection to optical transceivers and a second multiplexer/demultiplexer comprising transmit/receive ports for connection to other optical transceivers,

specifying a wavelength capable of being transmitted and received by the optical transceiver according to a transmission/reception port of a first multiplexer/demultiplexer to which the optical transceiver is connected, an

Wavelengths that can be transmitted and received by the other optical transceivers are specified according to the transmission/reception ports of the second multiplexer/demultiplexer to which the other optical transceivers are connected.

(supplementary notes 19)

An optical communication method, comprising:

a first output step performed by the first optical transceiver, the first output step outputting the first optical signal to an optical fiber while switching a wavelength of the first optical signal, the optical fiber serving as a medium for carrying single-fiber bidirectional communication between the first optical transceiver and an opposing second optical transceiver;

a second output step performed by the second optical transceiver, the second output step identifying a wavelength of the received first optical signal when the wavelength of the first optical signal is switched to a receivable wavelength, and outputting a second optical signal having a wavelength determined based on the identification result to the optical fiber; and

a stopping step performed by the first optical transceiver when the first optical transceiver receives the second optical signal from the optical fiber, the stopping step stopping switching the wavelength of the first optical signal.

(supplementary notes 20)

The optical communication method according to supplementary note 19, wherein,

a first output step outputs a first optical signal to the optical fiber, the first optical signal including information indicating a wavelength of the first optical signal, an

The second outputting step identifies a wavelength of the received first optical signal based on the information.

(supplementary notes 21)

The optical communication method according to supplementary note 19 or 20, wherein the second output step determines, as the wavelength of the second optical signal, a transmission wavelength corresponding to a reception wavelength that matches the wavelength indicated by the identification result, based on the correspondence between the reception wavelength and the transmission wavelength and the identification result.

(supplementary notes 22)

The optical communication method according to supplementary note 19 or 20, further comprising:

a stopping step, performed by the first optical transceiver, of stopping outputting the first optical signal even if the second optical signal is not successfully received from the optical fiber after performing the predetermined number of wavelength switchings,

a third output step performed by the second optical transceiver in a case where the second optical transceiver is connected after stopping outputting the first optical signal, the third output step outputting the second optical signal to the optical fiber while switching a wavelength of the second optical signal;

a fourth output step performed by the first optical transceiver, the fourth output step identifying a wavelength of the received second optical signal when the wavelength of the second optical signal is switched to a receivable wavelength, and outputting an optical signal having a wavelength determined based on the identification result as the first optical signal to the optical fiber; and

a stopping step performed by the second optical transceiver when the second optical transceiver receives the first optical signal from the optical fiber, the stopping step stopping switching the wavelength of the second optical signal.

(supplementary notes 23)

The optical communication method according to supplementary note 22, wherein,

the second output step determines, as the wavelength of the second optical signal, the transmission wavelength corresponding to the reception wavelength that matches the wavelength indicated by the identification result, based on the correspondence between the reception wavelength and the transmission wavelength and the identification result, and

the fourth output step determines, as the wavelength of the first optical signal, the transmission wavelength corresponding to the reception wavelength that matches the wavelength indicated by the identification result, based on the correspondence and the identification result.

(supplementary notes 24)

The optical communication method according to any one of supplementary notes 19 to 23, wherein

The optical fiber is arranged between a first multiplexer/demultiplexer comprising a transmit port and a receive port for connection to a first optical transceiver and a second multiplexer/demultiplexer comprising a transmit port and a receive port for connection to a second optical transceiver,

specifying respective wavelengths capable of being transmitted from and received by the first optical transceiver according to a transmission port and a reception port of a first multiplexer/demultiplexer to which the first optical transceiver is connected, an

The respective wavelengths that can be transmitted from and received by the second optical transceiver are specified according to the transmission port and the reception port of the second multiplexer/demultiplexer to which the second optical transceiver is connected.

(supplementary notes 25)

The optical communication method according to any one of supplementary notes 19 to 23, wherein,

the optical fiber is arranged between a first multiplexer/demultiplexer comprising a transmit/receive port for connection to a first optical transceiver and a second multiplexer/demultiplexer comprising a transmit/receive port for connection to a second optical transceiver,

specifying a wavelength capable of being transmitted and received by the first optical transceiver according to a transmission/reception port of the first multiplexer/demultiplexer to which the first optical transceiver is connected, an

The wavelengths that can be transmitted and received by the second optical transceiver are specified according to the transmission/reception port of the second multiplexer/demultiplexer to which the second optical transceiver is connected.

(supplementary notes 26)

A program causing a control computer provided in an optical transceiver to execute a process comprising:

a switching step of switching a wavelength of a first optical signal to be output to an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver and the other optical transceiver as opposed; and

a stopping step of stopping switching of the wavelength of the first optical signal when receiving a second optical signal which has a wavelength previously associated with the wavelength of the first optical signal and is output when the other optical transceiver receives the first optical signal.

(supplementary notes 27)

The program according to supplementary note 26, wherein the switching step includes the step of including information indicating the wavelength of the first optical signal in the first optical signal.

(supplementary notes 28)

A program causing a control computer provided in an optical transceiver to execute a process, the process comprising:

an identifying step of identifying a wavelength of a received first optical signal when the first optical signal output while switching the wavelength of the first optical signal is received from an optical fiber serving as a medium for carrying single-fiber bidirectional communication between an optical transceiver and another optical transceiver opposite thereto;

a determination step of determining a transmission wavelength based on the recognition result from the recognition step; and

a switching step of switching a wavelength of the second optical signal to be output to the optical fiber so that the wavelength of the second optical signal is the transmission wavelength determined in the determining step.

(supplementary notes 29)

The program according to supplementary note 28, wherein the identifying step identifies the wavelength of the first optical signal received from the other optical transceiver based on information included in the first optical signal.

(supplementary notes 30)

The program according to supplementary note 28 or 29, wherein the determining step determines, as the transmission wavelength of the second optical signal, the transmission wavelength corresponding to the reception wavelength that matches the wavelength indicated by the identification result, based on the identification result and the correspondence between the reception wavelength and the transmission wavelength.

(supplementary notes 31)

A program causing a control computer provided in an optical transceiver to execute a process, the process comprising:

a first switching step of switching a wavelength of a first optical signal to be output to an optical fiber serving as a medium for carrying single-fiber bidirectional communication between the optical transceiver and the other optical transceiver as opposed;

a stopping step of stopping switching of the wavelength of the first optical signal when receiving a second optical signal which has a wavelength previously associated with the wavelength of the first optical signal and is output when the other optical transceiver receives the first optical signal;

an identifying step of identifying, when a third optical signal output while switching a wavelength of the third optical signal is received from the optical fiber, the wavelength of the received third optical signal;

a determination step of determining a transmission wavelength based on the recognition result from the recognition step; and

a second switching step of switching a wavelength of a fourth optical signal to be output to the optical fiber so that the wavelength of the fourth optical signal is the transmission wavelength determined in the determining step, wherein,

the wavelength of the third optical signal receivable from the optical fiber is the wavelength of the second optical signal, an

The wavelength of the fourth optical signal determined in the determining step is a wavelength of the first optical signal receivable by the other optical transceiver.

(supplementary notes 32)

The program according to supplementary note 31, wherein,

the first switching step comprises the step of including information indicative of the wavelength of the first optical signal in the first optical signal, an

The identifying step identifies the wavelength of the third optical signal received from the other optical transceiver based on information included in the third optical signal.

(supplementary notes 33)

The program according to supplementary note 31 or 32, wherein,

the first switching step includes a stopping step of stopping outputting the first optical signal even if the second optical signal is not successfully received from the optical fiber after the predetermined number of wavelength switching is performed, and

in the case where the third optical signal is successfully received from the optical fiber after the output of the first optical signal is stopped, the identifying step identifies the wavelength of the successfully received third optical signal.

(supplementary notes 34)

The program according to any one of supplementary notes 31 to 33, wherein the determination step determines, as the wavelength of the fourth optical signal, the transmission wavelength corresponding to the reception wavelength that matches the wavelength indicated by the identification result, based on the correspondence between the reception wavelength and the transmission wavelength and the identification result.

The present invention has been described with reference to the exemplary embodiments, but the present invention is not limited to the above. Various modifications, which will occur to those skilled in the art, may be made in the arrangement and details of the invention within the scope of the invention.

This application claims priority from japanese patent application No. 2019-.

List of reference numerals

1. 11-1 first optical transceiver

1a, 2a control unit

1b, 2b optical output unit

1c, 2c optical input unit

2. 21-n second optical transceiver

3 optical fiber

10 first terminal station

11. 11-2, 11-n first terminal station side optical transceiver

12 first multiplexer/demultiplexer

20 second terminal station

21. 21-2 first terminal station side optical transceiver

22 second multiplexer/demultiplexer

50 form

100 optical transceiver

101 processor

102 memory

103 interface