Method and device for demultiplexing polarization and polarization multiplexing self-homodyne detection system

文档序号：346343 发布日期：2021-12-03 浏览：13次中文

阅读说明：本技术 解偏振复用的方法、装置及偏振复用自零差探测系统 (Method and device for demultiplexing polarization and polarization multiplexing self-homodyne detection system ) 是由张森左天健于 2020-05-30 设计创作，主要内容包括：本申请实施例提供了一种解偏振复用的方法、装置、偏振复用自零差探测系统、存储介质及通信装置,采集收端信号的直流分量,根据直流分量生成偏振态旋转信息,根据偏振态旋转信息对偏振控制器的参数进行调整,通过基于各直流分量对偏振态旋转信息进行确定,并基于偏振态旋转信息对偏振控制器的参数进行调整,相较于相关技术,避免了基于盲搜索的方式对调整偏振控制器的参数进行调整造成的耗时较长,且准确性偏低的问题,实现了快速响应偏振态变化且输出精确可靠的信号的技术效果。(The embodiment of the application provides a method and a device for demultiplexing polarization, a polarization multiplexing self-homodyne detection system, a storage medium and a communication device, wherein a direct current component of a receiving end signal is collected, polarization state rotation information is generated according to the direct current component, parameters of a polarization controller are adjusted according to the polarization state rotation information, the polarization state rotation information is determined based on each direct current component, and the parameters of the polarization controller are adjusted based on the polarization state rotation information.)

1. A method for polarization demultiplexing, the method being applied to a polarization multiplexed self-homodyne detection system, the method comprising:

collecting a direct current component of a receiving end signal;

generating polarization state rotation information according to the direct current component and preset calibration parameters;

and adjusting parameters of a polarization controller in the polarization multiplexing self-homodyne detection system according to the polarization state rotation information.

2. The method of claim 1, wherein the calibration parameters comprise: direct current component calibration parameters and attenuation coefficient calibration parameters.

3. The method of claim 2, further comprising:

and determining the direct current component calibration parameter according to the power of the signal light and the power of the local oscillator light.

4. The method of claim 3, wherein the DC component calibration parameters comprise: the maximum value of the dc component; and/or, a minimum value of the direct current component.

5. The method according to claim 4, wherein if the power of the originating signal light is greater than the power of the local oscillator light, the calibration parameter of the direct current component is the maximum value of the direct current component; and if the power of the signal light at the transmitting end is less than that of the local oscillation light, the direct current component calibration parameter is the minimum value of the direct current component.

6. The method according to claim 4 or 5, characterized in that the method further comprises:

and traversing the azimuth angle and the phase difference in the polarization state rotation information by 0-2 pi randomly, counting the direct current component in a preset time period, and extracting the maximum value and/or the minimum value from the direct current component.

7. An apparatus for demultiplexing polarization, the apparatus being applied to a polarization-multiplexed self-homodyne detection system, the apparatus comprising:

the acquisition module is used for acquiring the direct current component of the receiving end signal;

the generating module is used for generating polarization state rotation information according to the direct current component and preset calibration parameters;

and the adjusting module is used for adjusting the parameters of the polarization controller in the polarization multiplexing self-homodyne detection system according to the polarization state rotation information.

8. The apparatus of claim 7, wherein the calibration parameters comprise: direct current component calibration parameters and attenuation coefficient calibration parameters.

9. The apparatus of claim 8, further comprising:

and the determining module is used for determining the direct current component calibration parameter according to the power of the signal light and the power of the local oscillator light which are sent by the sending end.

10. The apparatus of claim 9, wherein the dc component calibration parameters comprise: the maximum value of the dc component; and/or, a minimum value of the direct current component.

11. The apparatus according to claim 10, wherein the determining module is configured to determine the dc component calibration parameter as a maximum value of the dc component if the power of the originating signal light is greater than the power of the local oscillator light; and if the power of the signal light at the transmitting end is smaller than that of the local oscillation light, determining the direct current component calibration parameter as the minimum value of the direct current component.

12. The apparatus of claim 10 or 11, further comprising:

and the calibration module is used for traversing the azimuth angle and the phase difference in the polarization state rotation information by 0-2 pi randomly, counting the direct current component in a preset time period, and extracting the maximum value and/or the minimum value from the direct current component.

13. A polarization multiplexed self-homodyne detection system, the system comprising: a laser, a polarization beam splitter, an optical modulator, a polarization beam combiner, a polarization controller, a polarization beam splitting rotator, an optical mixer, two ac-coupled balanced photodetectors, and an optical digital signal processor, wherein the polarization multiplexed self-homodyne detection system further comprises the apparatus of any of claims 7 to 12.

14. The system of claim 13, wherein the two AC-coupled balanced photodetectors are adapted as two balanced photodetectors with monitor ports,

the system comprises a balance photoelectric detector with a monitoring port, a signal processing module and a signal processing module, wherein the balance photoelectric detector with the monitoring port is used for outputting a direct current component of an I-path signal;

and the other balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the Q-path signal.

15. The system of claim 13, wherein the two AC-coupled balanced photodetectors are adapted as two DC-coupled balanced photodetectors, wherein,

a DC-coupled balanced photodetector for outputting the DC component of the I-path signal;

the other DC-coupled balanced photodetector is used for outputting a DC component of the Q-path signal.

16. The system of claim 13, further comprising: two DC-coupled balanced photodetectors connected to the means for demultiplexing and an optical mixer connected to the two DC-coupled balanced photodetectors and the polarization beam splitting rotator, respectively, wherein,

the optical mixer is used for mixing at least part of optical signals separated from the two paths of optical signals output by the polarization beam splitting rotator;

one of the two direct-current coupled balanced photodetectors is arranged for outputting a direct-current component of the I-path signal according to the optical signal after frequency mixing;

the other of the two dc-coupled balanced photodetectors is configured to output a dc component of the Q-path signal based on the mixed optical signal.

17. The system of claim 13, wherein the system comprises: two dc-coupled balanced photodetectors connected respectively to the optical mixer and to said means for demultiplexing, wherein,

one of the two direct-current coupled balanced photodetectors is arranged for outputting a direct-current component of the I-path signal according to the optical signal after frequency mixing;

and the other one of the two DC-coupled balanced photodetectors is arranged for outputting the DC component of the Q-path signal according to the mixed optical signal.

18. The system of claim 13, wherein the two ac-coupled balanced photodetectors are adapted as two balanced photodetectors with monitor ports, the system comprising: a photodetector disposed between the polarization beam splitter rotator and the means for demultiplexing, wherein,

the balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the I-path signal;

the other balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the Q-path signal;

the photoelectric detector arranged between the polarization beam splitting rotator and the device for demultiplexing polarization is used for outputting a direct current component of an Rx path signal; and/or, outputting the direct current component of the Ry path signal;

wherein, the Rx path signal is a signal output by the photodetector from at least a part of optical signals separated from one of the two optical signals; and the Ry path signal is a signal which is output by the photoelectric detector and is at least partially separated from the other optical signal in the two optical signals.

19. The system of claim 13, wherein the two ac-coupled balanced photodetectors are adapted as two balanced photodetectors with monitor ports, the system comprising: a DC-coupled balanced photodetector disposed between the polarization beam splitter rotator and the means for demultiplexing, wherein,

the balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the I-path signal;

the other balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the Q-path signal;

the direct-current coupled balanced photoelectric detector arranged between the polarization beam splitter rotator and the device for demultiplexing polarization is used for outputting a direct-current component of an Rd path signal;

and the direct current component of the Rd path signal is the difference of direct current components output by the balance photoelectric detector through direct current coupling of at least part of optical signals separated from the two paths of optical signals.

20. The system of claim 13, further comprising: two DC-coupled balanced photodetectors connected to the polarization demultiplexing device, an optical mixer connected to the two DC-coupled balanced photodetectors and the polarization beam splitting rotator, respectively, and a photodetector disposed between the polarization beam splitting rotator and the polarization demultiplexing device,

the optical mixer is used for mixing at least part of optical signals separated from the two paths of optical signals output by the polarization beam splitting rotator;

one of the two direct current coupled balanced photodetectors is arranged for outputting a direct current component of the I-path signal according to the optical signal after frequency mixing;

the other one of the two direct current coupled balanced photodetectors is used for outputting a direct current component of the Q-path signal according to the optical signal after frequency mixing;

the photoelectric detector is arranged between the polarization beam splitting rotator and the device for demultiplexing polarization and is used for outputting a direct current component of an Rx path signal; and/or outputting the direct current component of the Ry path signal.

21. The system of claim 13, further comprising: the polarization splitting device comprises two direct current coupled balanced photoelectric detectors connected with the device for demultiplexing polarization, an optical mixer connected with the two direct current coupled balanced photoelectric detectors and the polarization splitting rotator respectively, and a direct current coupled balanced photoelectric detector arranged between the polarization splitting rotator and the device for demultiplexing polarization, wherein the arranged optical mixer is used for mixing at least part of optical signals separated from two paths of optical signals output by the polarization splitting rotator;

one of the two DC-coupled balanced photodetectors behind the optical mixer is used for outputting the DC component of the I-path signal according to the optical signal after frequency mixing;

the other one of the two DC-coupled balanced photodetectors behind the optical mixer is used for outputting the DC component of the Q-path signal according to the optical signal after the frequency mixing;

and the direct-current coupled balanced photoelectric detector arranged between the polarization beam splitting rotator and the device for demultiplexing polarization is used for outputting a direct-current component of the Rd path signal.

22. A computer storage medium having stored thereon computer instructions which, when executed by a processor, cause the method of any of claims 1 to 6 to be performed.

23. An apparatus for demultiplexing polarization, comprising:

at least one processor; and

a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,

the memory stores computer instructions executable by the at least one processor, the computer instructions being executable by the at least one processor to cause the method of any one of claims 1 to 6 to be performed.

24. A communications apparatus, comprising:

the input interface is used for acquiring the direct current component of the receiving end signal;

logic circuitry for performing the method of any one of claims 1 to 6, obtaining polarization state rotation information;

and the output interface is used for adjusting the parameters of the polarization controller in the polarization multiplexing self-homodyne detection system according to the polarization state rotation information.

Technical Field

The present application relates to the field of signal processing technologies, and in particular, to the field of self-homodyne detection systems, and more particularly, to a method and an apparatus for demultiplexing polarization, a polarization multiplexing self-homodyne detection system, a storage medium, and a communication apparatus.

Background

Polarization multiplexing Self-Homodyne Detection (PDM-SHD) is used for characterizing a system which adopts one Polarization state to transmit local oscillator light and the other Polarization state to transmit signal light, and the signal light and the local oscillator light are transmitted in the same optical fiber.

In the transmission process of signal light and local oscillation light, signal crosstalk may be caused by optical fibers due to factors such as circular asymmetry, internal stress, pressure, bending and environmental temperature change in the production process. In order to solve the problem of signal crosstalk, the prior art generally adopts the following methods: a Polarization Controller (PC) is inserted before the Polarization beam splitter PSR, and the Polarization Controller PC is feedback-controlled by tracking the change of the Polarization state of the output light of the Polarization beam splitter PSR in real time, so that the receiving end Polarization beam splitter PBS splits the signal light and the local oscillator light.

However, in the process of implementing the invention, the inventor finds that the prior art has at least the following problems: because the feedback control polarization controller PC is generally implemented by using an adaptive algorithm (such as a gradient algorithm, etc.), the algorithm principle is based on blind search of the maximum value or the minimum value of a certain parameter (such as power), the maximum value or the minimum value can be converged to a target value after iteration for at least dozens of times to hundreds of times, each cycle needs to detect the current power value, and the working voltage or the working current of the polarization controller PC needs to be adjusted and issued next step is calculated so that the polarization controller PC works. Therefore, a problem may arise in that it takes a long time and thus the tracking speed of the polarization state is limited.

Disclosure of Invention

In order to solve the foregoing technical problem, embodiments of the present application provide a method and an apparatus for demultiplexing polarization, a polarization multiplexing self-homodyne detection system, a storage medium, and a communication apparatus.

According to an aspect of an embodiment of the present application, there is provided a method for polarization-division multiplexing, the method being applied to a polarization-division multiplexing self-homodyne detection system, the method including:

collecting a direct current component of a receiving end signal;

generating polarization state rotation information according to the direct current component and preset calibration parameters;

and adjusting parameters of a polarization controller in the polarization multiplexing self-homodyne detection system according to the polarization state rotation information.

In the embodiment of the application, the polarization state rotation information is determined based on each direct current component, and the parameters of the polarization controller are adjusted based on the polarization state rotation information, so that compared with the related art, the problems that time consumption is long and accuracy is low when the parameters of the polarization controller are adjusted based on a blind search mode are solved, and the technical effects of quickly tracking polarization state changes and outputting accurate and reliable signals are achieved.

In some embodiments, the calibration parameters include: direct current component calibration parameters and attenuation coefficient calibration parameters.

In some embodiments, the method further comprises:

and determining the direct current component calibration parameter according to the power of the signal light and the power of the local oscillator light.

In some embodiments, the dc component calibration parameters include: the maximum value of the dc component; and/or, a minimum value of the direct current component.

In some embodiments, if the power of the signal light at the transmitting end is greater than the power of the local oscillator light, the calibration parameter of the direct current component is the maximum value of the direct current component; and if the power of the signal light at the transmitting end is less than that of the local oscillation light, the direct current component calibration parameter is the minimum value of the direct current component.

In some embodiments, the method further comprises:

According to another aspect of the embodiments of the present application, there is also provided an apparatus for demultiplexing polarization, the apparatus being applied to a polarization-multiplexed self-homodyne detection system, the apparatus including:

the acquisition module is used for acquiring the direct current component of the receiving end signal;

the generating module is used for generating polarization state rotation information according to the direct current component and preset calibration parameters;

and the adjusting module is used for adjusting parameters of a polarization controller PC in the polarization multiplexing self-homodyne detection system according to the polarization state rotation information.

In some embodiments, the calibration parameters include: direct current component calibration parameters and attenuation coefficient calibration parameters.

In some embodiments, the apparatus further comprises:

In some embodiments, the dc component calibration parameters include: the maximum value of the dc component; and/or, a minimum value of the direct current component.

In some embodiments, the determining module is configured to determine the dc component calibration parameter as a maximum value of the dc component if the power of the signal light at the transmitting end is greater than the power of the local oscillator light; and if the power of the signal light at the transmitting end is smaller than that of the local oscillation light, determining the direct current component calibration parameter as the minimum value of the direct current component.

In some embodiments, the apparatus further comprises:

According to another aspect of the embodiments of the present application, there is also provided a polarization multiplexing self-homodyne detection system, including: the polarization multiplexing self-homodyne detection system comprises a laser, a polarization beam splitter, an optical modulator, a polarization beam combiner, a polarization controller, a polarization beam splitting rotator, an optical mixer, two alternating-current coupled balanced photodetectors and an optical digital signal processor, and further comprises the device in any one of the embodiments.

In some embodiments, the two ac-coupled balanced photodetectors are adapted such that, two balanced photodetectors with monitoring ports,

and the other balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the Q-path signal.

In some embodiments, two ac-coupled balanced photodetectors are adapted to two dc-coupled balanced photodetectors, wherein,

a DC-coupled balanced photodetector for outputting the DC component of the I-path signal;

the other DC-coupled balanced photodetector is used for outputting a DC component of the Q-path signal.

In some embodiments, the system comprises: two DC-coupled balanced photodetectors connected to the means for demultiplexing and an optical mixer connected to the two DC-coupled balanced photodetectors and the polarization beam splitting rotator, respectively, wherein,

the optical mixer is used for mixing at least part of optical signals separated from the two paths of optical signals output by the polarization beam splitting rotator;

one of the two direct-current coupled balanced photodetectors is arranged for outputting a direct-current component of the I-path signal according to the optical signal after frequency mixing;

the other of the two dc-coupled balanced photodetectors is configured to output a dc component of the Q-path signal based on the mixed optical signal.

In some embodiments, the system comprises: two dc-coupled balanced photodetectors connected respectively to the optical mixer and to said means for demultiplexing, wherein,

one of the two direct-current coupled balanced photodetectors is arranged for outputting a direct-current component of the I-path signal according to the optical signal after frequency mixing;

and the other one of the two DC-coupled balanced photodetectors is arranged for outputting the DC component of the Q-path signal according to the mixed optical signal.

In some embodiments, the two ac-coupled balanced photodetectors are adapted as two balanced photodetectors with monitoring ports, the system comprising: a photodetector disposed between the polarization beam splitter rotator and the means for demultiplexing, wherein,

the balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the I-path signal;

the other balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the Q-path signal;

In some embodiments, the two ac-coupled balanced photodetectors are adapted as two balanced photodetectors with monitoring ports, the system comprising: a DC-coupled balanced photodetector disposed between the polarization beam splitter rotator and the means for demultiplexing, wherein,

the balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the I-path signal;

the other balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the Q-path signal;

In some embodiments, the system further comprises: two DC-coupled balanced photodetectors connected to the polarization demultiplexing device, an optical mixer connected to the two DC-coupled balanced photodetectors and the polarization beam splitting rotator, respectively, and a photodetector disposed between the polarization beam splitting rotator and the polarization demultiplexing device,

the optical mixer is used for mixing at least part of optical signals separated from the two paths of optical signals output by the polarization beam splitting rotator;

one of the two direct current coupled balanced photodetectors is arranged for outputting a direct current component of the I-path signal according to the optical signal after frequency mixing;

the other one of the two direct current coupled balanced photodetectors is used for outputting a direct current component of the Q-path signal according to the optical signal after frequency mixing;

In some embodiments, the system further comprises: two DC-coupled balanced photodetectors connected to the de-polarization multiplexing device, an optical mixer connected to the two DC-coupled balanced photodetectors and the polarization beam splitting rotator, respectively, and a DC-coupled balanced photodetector disposed between the polarization beam splitting rotator and the de-polarization multiplexing device, wherein,

the optical mixer is used for mixing at least part of optical signals separated from the two paths of optical signals output by the polarization beam splitting rotator;

one of the two DC-coupled balanced photodetectors behind the optical mixer is used for outputting the DC component of the I-path signal according to the optical signal after frequency mixing;

According to another aspect of the embodiments of the present application, there is also provided a computer storage medium having stored thereon computer instructions, which, when executed by a processor, cause the method of any of the above embodiments to be performed.

According to another aspect of the embodiments of the present application, there is also provided an apparatus for demultiplexing polarization, including:

at least one processor; and

a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,

According to another aspect of the embodiments of the present application, there is also provided a communication apparatus, including:

the input interface is used for acquiring the direct current component of the receiving end signal;

logic circuitry for performing a method as in any one of the above embodiments to obtain polarization rotation information;

and the output interface is used for adjusting the parameters of the polarization controller PC in the polarization multiplexing self-homodyne detection system according to the polarization state rotation information.

Drawings

The drawings are included to provide a further understanding of the embodiments of the application and are not intended to limit the application. Wherein the content of the first and second substances,

fig. 1 is a schematic view of an application scenario according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a polarization-multiplexed self-homodyne detection system in the related art;

FIG. 3 is a schematic flow chart of a method for demultiplexing polarization in accordance with an embodiment of the present application;

FIG. 4 is a schematic diagram of an apparatus for a method of demultiplexing polarization in accordance with an embodiment of the present application;

FIG. 5 is a schematic diagram of a polarization-multiplexed self-homodyne detection system provided by an embodiment of the present application;

FIG. 6 is a schematic diagram of a polarization-multiplexed self-homodyne detection system provided in another embodiment of the present application;

FIG. 7 is a schematic diagram of a polarization-multiplexed self-homodyne detection system provided in another embodiment of the present application;

FIG. 8 is a schematic diagram of a polarization multiplexed self-homodyne detection system provided in another embodiment of the present application;

FIG. 9 is a schematic diagram of a polarization-multiplexed self-homodyne detection system provided in another embodiment of the present application;

FIG. 10 is a schematic diagram of a polarization multiplexed self-homodyne detection system provided in another embodiment of the present application;

FIG. 11 is a schematic diagram of a polarization multiplexed self-homodyne detection system provided in another embodiment of the present application;

FIG. 12 is a schematic diagram of a polarization multiplexed self-homodyne detection system provided in another embodiment of the present application;

FIG. 13 is a schematic diagram of a polarization multiplexed self-homodyne detection system provided in another embodiment of the present application;

FIG. 14 is a schematic diagram of a polarization multiplexed self-homodyne detection system provided in another embodiment of the present application;

FIG. 15 is a schematic diagram of a polarization multiplexed self-homodyne detection system provided in another embodiment of the present application;

FIG. 16 is a schematic diagram of a balanced photodetector with a monitor port according to the related art;

fig. 17 is a schematic diagram of a dc-coupled balanced photodetector and a photodetector according to the related art.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

Referring to fig. 1, fig. 1 is a schematic view of an application scenario according to an embodiment of the present application.

In the application scenario shown in fig. 1, the network element includes two network elements, which are a network element a and a network element B, and an optical module is inserted into each of the two network elements, where an optical module inserted into the network element a is referred to as an optical module a, and an optical module inserted into the network element B is referred to as an optical module B.

The information sent by the network element a to the network element B modulates an electrical signal to signal light through a sending end of an optical module a, the sending end of the optical module a uses one polarization state to transmit the signal light and uses the other polarization state to transmit local oscillator light, as Tx shown in fig. 2 (where fig. 2 is a schematic diagram of a polarization multiplexing self-homodyne detection system and will be described in detail later). Optical signals (including signal light and local oscillator light) are transmitted from a transmitting end of the optical module A to a receiving end of the optical module B through an optical fiber link, and are converted into electric signals after being demodulated by the optical module B. The receiving end of the optical module B is Rx as shown in fig. 2.

Similarly, optical signals (including signal light and local oscillator light) are transmitted from the transmitting end of the optical module B to the receiving end of the optical module a through the optical fiber link, and are demodulated and converted into electrical signals by the optical module a.

Referring to fig. 2, fig. 2 is a schematic diagram of a polarization-multiplexed self-homodyne detection system in the related art.

As shown in fig. 2, the light from the laser is split into two orthogonal Polarization states, X and Y, by a Polarizing Beam Splitter (PBS).

The light in the X polarization state may be modulated by the optical modulator to become signal light, and the light in the Y polarization state may not be modulated.

It should be understood that, in the embodiment of the present application, it is only exemplarily illustrated that the X polarization state may be the signal light, and the Y polarization state may be the local oscillator light, and in other embodiments, the X polarization state may be the local oscillator light, and the Y polarization state may be the signal light.

The light of two Polarization states is combined into a Beam by a Polarization Beam Combiner (PBC) and output to an optical Fiber link, such as an optical Fiber link composed of Single Mode Fiber (SMF), and the length of the optical Fiber link can be set according to requirements, such as 2km and 10 km.

One of the resultant lights is divided into two lights with the same Polarization state, such as lights with X Polarization state, by a Polarization beam Splitter Rotator (PSR).

The Polarization Beam Splitter Rotator PSR may be composed of a Polarization Beam Splitter (PBS) and a Polarization Rotator (PR), among others. The polarization beam splitter PBS may split an axially aligned input beam containing two polarization directions into two orthogonal linear polarization states, and the polarization rotator PR may rotate one of the polarization states by a fixed angle (e.g., 90 °), for example, so that the Y polarization state is changed to the X polarization state.

Two paths of light with the same polarization state are subjected to frequency mixing through an Optical mixer 90-degree Hybrid, then are converted into electric signals through two alternating current coupled Balanced Photodetectors (BPD), namely an I path Signal and a Q path Signal, and then are sent to an Optical Digital Signal Processor (ODSP) for Digital Signal Processing. Wherein the two ac-coupled balanced photodetectors may be BPD1 and BPD2 as shown in fig. 2.

It should be noted that due to factors such as circular asymmetry, internal stress, pressure during use, bending, and ambient temperature change in the optical fiber link during production of the optical fiber link, a random birefringence effect may be generated in the optical fiber link, so that the polarization state of light input to the optical fiber link may be randomly changed when the light is output, which may be referred to as an optical fiber polarization rotation effect, and the optical fiber polarization rotation effect may cause polarization crosstalk to occur in the respective optical signals in the X-polarization state and the Y-polarization state at two outputs of the polarization beam splitter PBS. That is, the X and Y signals output by the polarization beam splitter rotator PSR both include the light in the originating X polarization state and the light in the originating Y polarization state. Here, a signal of light in the X polarization state (i.e., signal light) is referred to as an X signal, and a signal of light in the Y polarization state (i.e., local oscillation light) is referred to as a Y signal. The fiber polarization rotation effect can be represented by jones matrix:

wherein, theta is a rotation angle,they are all quantities that vary randomly over time.

In the related art, in order to solve the problem of Polarization crosstalk occurring at the output of the Polarization beam splitter PBS due to the fiber Polarization rotation effect, a Polarization Controller (PC) may be inserted before the Polarization beam splitter PSR, and the Polarization Controller PC is controlled by real-time tracking the Polarization state change of the output light of the Polarization beam splitter PSR and feeding back, so that the receiving end Polarization beam splitter PBS splits the signal light and the local oscillation light. The polarization rotation effect of the polarization controller PC on the input light can be represented by the jones matrix as:

wherein, theta₃Is the angle of rotation,they may vary with the applied control voltage or control current, as phase angles.

The polarization controller PC is an optical device for controlling polarization state, and can convert one path of input light with any polarization state into another path of output light with any polarization state. Based on the above two equations, it can be understood that the equivalent polarization rotation effect of the fiber and the polarization controller PC is expressed as:

it can be seen that if the polarization controller PC is kept up with the fiber polarization rotation, θ is satisfied₃＝-θ，The optical domain depolarization multiplexing of the input signal can be realized, and the polarization beam splitting rotator PSR can output two paths of optical signals without polarization crosstalk.

However, when the solution of setting the polarization controller PC in the related art is used for polarization demultiplexing, an adaptive algorithm (such as a gradient algorithm) is generally used for implementation, and the algorithm principle is based on blind search of a maximum value or a minimum value of a certain parameter (such as a power value, etc.), iteration is generally performed at least dozens of times to hundreds of times to converge to a target value, each cycle needs to detect a current power value, calculate a working voltage or a working current of the polarization controller PC, which needs to be adjusted next step, and issue the working voltage or the working current of the polarization controller PC to enable the polarization controller PC to operate. Therefore, it may cause a problem that it takes a long time to track the polarization state at a limited speed.

The inventor of the application obtains the inventive concept of the application through creative work: the polarization state rotation information caused by the optical fiber polarization rotation effect is determined according to the direct current component, and the parameters of the polarization controller PC are adjusted according to the polarization state rotation information, so that the signal received by the receiving end (as shown in fig. 1, if the network element a is the transmitting end, the receiving end is the network element B, and if the network element B is the transmitting end, the receiving end is the network element a) is a signal which is not subjected to polarization crosstalk.

The following describes the technical solutions of the present application and how to solve the above technical problems with specific embodiments. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments. Embodiments of the present application will be described below with reference to the accompanying drawings.

According to an aspect of the embodiments of the present application, the embodiments of the present application provide a method for demultiplexing polarization, which may be applied to a polarization-multiplexed self-homodyne detection system.

Referring to fig. 3, fig. 3 is a flowchart illustrating a method for demultiplexing polarization according to an embodiment of the present application.

As shown in fig. 3, the method includes:

s101: and collecting the direct current component of the receiving end signal.

The execution main body of the method for demultiplexing polarization according to the embodiment of the present application may be a device for demultiplexing polarization, and the device may be a calculation control unit, the calculation control unit may specifically be a chip having a calculation processing function, and the calculation control unit may be a chip independent from the optical signal digital processor ODSP, or may also be a chip integrated in the optical signal digital processor ODSP.

In the embodiment of the present application, each dc component may be collected in a plurality of ways, and the number of the dc components in the embodiment of the present application is not limited, that is, the number of the dc components is at least two.

That is to say, in the embodiment of the present application, the acquisition manner of each dc component is not limited, and the number of the dc components is not limited, as set forth in the following embodiments: the alternating-current coupled balanced photoelectric detector BPD can be replaced by a direct-current coupled balanced photoelectric detector BPD; a dc output port may also be disposed after the ac-coupled balanced photodetector BPD for outputting each dc component, and the dc output port is connected to the calculation control unit, and so on, which will be described later and will not be described herein again.

S102: and generating polarization state rotation information according to the direct current component and preset calibration parameters.

Based on the above example, both the fiber polarization rotation and the polarization controller may be equivalent to a jones matrix, and the polarization state rotation information may be an equivalent jones matrix parameter acted by the fiber and the polarization controller, so in this embodiment, after each dc component is determined, calculation may be performed based on each dc component to obtain the polarization state rotation information (if the equivalent is a jones matrix, the polarization state rotation information may be understood as a jones matrix parameter).

Of course, in other embodiments, the polarization rotation information may also be stokes matrix parameters or mueller matrix parameters, etc.

S103: and adjusting parameters of the polarization controller according to the polarization state rotation information.

Based on the above analysis, an embodiment of the present application provides a method for demultiplexing polarization, where the method includes: the method comprises the steps of collecting direct current components of receiving end signals, generating polarization state rotation information according to the direct current components, adjusting parameters of a polarization controller according to the polarization state rotation information, determining the polarization state rotation information based on the direct current components, and adjusting the parameters of the polarization controller based on the polarization state rotation information.

In some embodiments, the calibration parameters include: direct current component calibration parameters and attenuation coefficient calibration parameters.

In some embodiments, the dc component calibration parameter is determined according to the power of the signal light and the power of the local oscillator light.

In some embodiments, the dc component calibration parameters include: the maximum value of the dc component; and/or, a minimum value of the direct current component.

In some embodiments, if the dc component includes a dc component of the I-path signal and a dc component of the Q-path signal, or the dc component includes a dc component of the I-path signal, a dc component of the Q-path signal, and a dc component of the Rd-path signal, the dc component calibration parameter includes: a maximum or minimum of the dc component.

In some embodiments, if the dc components include a dc component of the I-path signal, a dc component of the Q-path signal, and a dc component of the Rx-path signal, or the dc components include a dc component of the I-path signal, a dc component of the Q-path signal, and a dc component of the Ry-path signal, the dc component calibration parameter includes: the maximum value or the minimum value of the direct current component of the I path signal and the direct current component of the Q path signal, and the direct current component calibration parameters further comprise: the maximum value and the minimum value of the direct current component of the Rx path signal and the maximum value and the minimum value of the direct current component of the Ry path signal.

In some embodiments, the method for generating the dc component calibration parameter includes: and traversing the azimuth angle and the phase difference in the polarization state rotation information by 0-2 pi randomly, counting the direct current component in a preset time period, and extracting the maximum value and/or the minimum value from the direct current component.

Wherein the time period may be set based on demand, experience, experiment, and the like.

According to another aspect of the embodiments of the present application, there is provided an apparatus for demultiplexing polarization, which is configured to perform the method according to the above embodiments, that is, perform the method shown in fig. 3.

Referring to fig. 4, fig. 4 is a schematic diagram illustrating an apparatus for a method of demultiplexing polarization according to an embodiment of the present application.

As shown in fig. 4, the apparatus includes:

and the acquisition module 11 is configured to acquire a direct current component of the receiving end signal.

And the generating module 12 is configured to generate polarization rotation information according to the direct current component and a preset calibration parameter.

And the adjusting module 13 is configured to adjust parameters of the polarization controller according to the polarization state rotation information.

In some embodiments, the calibration parameters include: direct current component calibration parameters and attenuation coefficient calibration parameters.

As can be seen in fig. 4, in some embodiments, the apparatus further comprises:

the determining module 14 is configured to determine a dc component calibration parameter according to the power of the signal light and the power of the local oscillator light.

In some embodiments, the dc component calibration parameters include: the maximum value of the dc component; and/or, a minimum value of the direct current component.

In some embodiments, the determining module 14 is configured to determine the dc component calibration parameter as a maximum value of the dc component if the power of the signal light at the transmitting end is greater than the power of the local oscillator light; and if the power of the signal light at the transmitting end is smaller than that of the local oscillation light, determining the direct current component calibration parameter as the minimum value of the direct current component.

As can be seen in fig. 4, in some embodiments, the apparatus further comprises:

and the calibration module 15 is configured to randomly traverse the azimuth angle and the phase difference in the polarization rotation information, count the direct current components in a preset time period, and extract a maximum value and/or a minimum value from the direct current components.

Wherein the time period may be set based on demand, experience, experiment, and the like.

According to another aspect of the embodiments of the present application, there is also provided a new polarization-multiplexed self-homodyne detection system.

Referring to fig. 5, fig. 5 is a schematic diagram of a polarization-multiplexed self-homodyne detection system according to an embodiment of the present application.

As shown in fig. 5, the system includes the polarization multiplexing self-homodyne detection system shown in fig. 2, and the description of the related components can refer to the above example, which is not repeated herein, in the embodiment of the present application, the system further includes a polarization demultiplexing device on the basis of the polarization multiplexing self-homodyne detection system in the related art, and the polarization demultiplexing device may specifically include a calculation control unit shown in fig. 5, and in some embodiments, the calculation control unit may be integrated in the optical digital signal processor in consideration of reasonable utilization of the calculation resources.

As can be seen in fig. 6, in some embodiments, two ac-coupled balanced photodetectors in a polarization multiplexed self-homodyne detection system are adapted as two balanced photodetectors with monitor ports, wherein,

the balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the I-path signal;

and the other balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the Q-path signal.

As can be seen in fig. 7, in some embodiments, two ac-coupled balanced photodetectors in a polarization multiplexed self-homodyne detection system are adapted to two dc-coupled balanced photodetectors,

wherein, a DC-coupled balanced photodetector is used for outputting the DC component of the I-path signal;

the other DC-coupled balanced photodetector is used for outputting a DC component of the Q-path signal.

As can be seen in fig. 8, in some embodiments, the polarization-multiplexed self-homodyne detection system further includes: two DC-coupled balanced photodetectors connected to the calculation control unit, and an optical mixer connected to the two DC-coupled balanced photodetectors and the polarization beam splitting rotator, respectively,

the optical mixer is used for mixing at least part of optical signals separated from the two paths of optical signals output by the polarization beam splitting rotator;

one of the two direct current coupled balanced photodetectors is arranged for outputting a direct current component of the I-path signal according to the optical signal after frequency mixing;

the other of the two dc-coupled balanced photodetectors is configured to output a dc component of the Q-path signal based on the mixed optical signal.

As can be seen in fig. 9, in some embodiments, the polarization-multiplexed self-homodyne detection system further includes: two DC-coupled balanced photodetectors respectively connected to the optical mixer and the calculation control unit, wherein,

one of the two direct current coupled balanced photodetectors is arranged for outputting a direct current component of the I-path signal according to the optical signal after frequency mixing;

the other of the two dc-coupled balanced photodetectors is configured to output a dc component of the Q-path signal based on the mixed optical signal.

As can be seen in fig. 10 and 11, in some embodiments, two ac-coupled balanced photodetectors in the polarization-multiplexed self-homodyne detection system are adjusted to be two balanced photodetectors with monitoring ports, and the polarization-multiplexed self-homodyne detection system further includes: a photodetector disposed between the polarization beam splitter rotator and the calculation control unit, wherein,

the balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the I-path signal;

the other balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the Q-path signal;

the photoelectric detector arranged between the polarization beam splitting rotator and the calculation control unit is used for outputting a direct current component of an Rx path signal; and/or, outputting the direct current component of the Ry path signal;

the Rx path signal is a signal which is output by a photoelectric detector from at least part of split optical signals in one path of optical signals in the two paths of optical signals; the Ry path signal is a signal output by the photodetector from the other of the two paths of optical signals.

As can be seen in fig. 12, in some embodiments, two ac-coupled balanced photodetectors in the polarization-multiplexed self-homodyne detection system are adjusted to be two balanced photodetectors with monitoring ports, and the polarization-multiplexed self-homodyne detection system further includes: a DC-coupled balanced photodetector disposed between the polarization beam splitter rotator and the computational control unit, wherein,

the balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the I-path signal;

the other balanced photoelectric detector with a monitoring port is used for outputting a direct current component of the Q-path signal;

the direct-current coupled balance photoelectric detector is arranged between the polarization beam splitting rotator and the calculation control unit and is used for outputting a direct-current component of the Rd path signal;

As can be seen in fig. 13 and 14, in some embodiments, the polarization-multiplexed self-homodyne detection system further includes: two DC-coupled balanced photodetectors connected to the calculation control unit, an optical mixer connected to the two DC-coupled balanced photodetectors and the polarization beam splitting rotator, respectively, and a photodetector disposed between the polarization beam splitting rotator and the calculation control unit,

the optical mixer is used for mixing at least part of optical signals separated from the two paths of optical signals output by the polarization beam splitting rotator;

one of the two direct current coupled balanced photodetectors is arranged for outputting a direct current component of the I-path signal according to the optical signal after frequency mixing;

the other of the two dc-coupled balanced photodetectors is configured to output a dc component of the Q-path signal based on the mixed optical signal.

The photoelectric detector arranged between the polarization beam splitting rotator and the calculation control unit is used for outputting a direct current component of an Rx path signal; and/or outputting the direct current component of the Ry path signal.

As can be seen in fig. 15, in some embodiments, the polarization-multiplexed self-homodyne detection system further includes: two DC-coupled balanced photodetectors connected to the calculation control unit, an optical mixer connected to the two DC-coupled balanced photodetectors and the polarization beam splitting rotator, respectively, and a DC-coupled balanced photodetector disposed between the polarization beam splitting rotator and the calculation control unit,

the optical mixer is used for mixing at least part of optical signals separated from the two paths of optical signals output by the polarization beam splitting rotator;

one of the two DC-coupled balanced photodetectors behind the optical mixer is used for outputting the DC component of the I-path signal according to the optical signal after frequency mixing;

and the other of the two DC-coupled balanced photodetectors arranged after the optical mixer is used for outputting the DC component of the Q-path signal according to the optical signal after the frequency mixing.

And the direct-current coupled balance photoelectric detector arranged between the polarization beam splitting rotator and the calculation control unit is used for outputting a direct-current component of the Rd path signal.

For the reader to more deeply understand the technical solution of the embodiments of the present application, the embodiments of the present application will now be described in more detail by taking polarization rotation information as an example of the jones matrix parameter, but it should be noted that the following examples are only for illustrative purposes and should not be construed as limiting the scope of the embodiments of the present application.

As can be seen from the above examples, in the related art, the balanced photodetector BPDs employed are ac-coupled balanced photodetector BPDs, such as the balanced photodetector BPDs 1 and BPD2 shown in fig. 2. Although the balanced photodetector BPD used in the related art self-homodyne detection system is an ac-coupled balanced photodetector BPD, in other technical fields, the balanced photodetector BPD may also include a dc-coupled balanced photodetector BPD, a balanced photodetector BPD with a monitor port, and the like, and in order to distinguish between different types of balanced photodetector BPDs, in the following embodiments, the description of "first", "second", and "third" is used,

the first balanced photoelectric detector BPD is used for representing and is provided with a monitoring port, wherein the monitoring port is a direct current output port and is used for outputting direct current components in the embodiment of the application; characterizing by a second balanced photoelectric detector BPD, and carrying out direct-current coupling on the balanced photoelectric detector BPD; and characterizing the third balanced photoelectric detector BPD by using the AC coupled balanced photoelectric detector BPD.

In addition, the balanced photodetector BPD may be divided into a high-speed balanced photodetector BPD and a low-speed balanced photodetector BPD. In the embodiment of the present application, when the embodiment is explained, the high-speed balanced photodetector BPD and the low-speed balanced photodetector BPD are not specifically subdivided, and in the practical application process, the high-speed balanced photodetector BPD or the low-speed balanced photodetector BPD may be selected according to corresponding service requirements, such as bandwidth requirements, for example, in the embodiment of the present application, when the balanced photodetector BPD is only used for outputting a dc component, the low-speed balanced photodetector BPD may be selected.

Since the embodiment of the present application needs to use a dc component, if a certain photodetector can output a dc component, the photodetector can be used in the present application. Therefore, the specific type and structure of the photodetector are not limited in the embodiments of the present application, for example, a low-speed dc-coupled photodetector may be adopted, and of course, a photodetector with a monitoring port may also be adopted, and so on, which are not described herein again.

Example 1

In order to realize the feedback control of the polarization controller PC, so that two paths of optical signals without polarization crosstalk are output through the polarization beam splitting rotator PSR, the embodiment of the present application provides a new polarization multiplexing self-homodyne detection system based on fig. 2.

As shown in fig. 6, in the polarization multiplexing self-homodyne detection system according to the embodiment of the present application, with respect to fig. 2, two third balanced photodetectors BPD as in fig. 2 may be adjusted to two first balanced photodetectors BPD as in fig. 6, such as the BPD1 and the BPD 2. For example, in fig. 6, the first balanced photodetector BPD1 is connected to the calculation control unit through the DC output port DC1, and the first balanced photodetector BPD2 is connected to the calculation control unit through the DC output port DC 2.

As shown in fig. 6, if the direct current component of the I-path signal output from the direct current output port DC1 isThe direct current component of the Q-path signal output by the direct current output port DC2 isThe calculation control unit calculates as a function of the DC componentAnd a direct current component ofAnd calculating to obtain polarization state rotation information, and tracking the polarization state by the polarization controller PC according to the polarization state rotation information.

It should be noted that the polarization-multiplexed self-homodyne detection system may include three stages in the processes of polarization state tracking, starting polarization state tracking, and the three stages of the polarization-multiplexed self-homodyne detection system are described in detail with reference to fig. 6.

The explanation of the stage before the polarization state tracking of the polarization multiplexing self-homodyne detection system is as follows:

and calibrating the parameters of the polarization multiplexing self-homodyne detection system to obtain calibration parameters.

For example, the calibrated parameters include: maximum or minimum DC component of I-path signal and Q-path signalAndand the ratio gamma of the attenuation coefficient calibration parameters of the I path signal and the Q path signal output₁/γ₂The specific selection of the maximum dc component or the minimum dc component depends on the power of the signal light and the power of the local oscillator light.

The calibration parameters may be calibrated based on requirements, experience, or tests, among others. For example, the azimuth angle and the phase delay amount in the equivalent Jones matrix parameter of the system can randomly traverse 0-2 pi by means of artificially disturbing the polarization controller PC, and the maximum or minimum value of the direct current component output by the I path signal and the maximum or minimum value of the direct current component output by the Q path signal are counted for a period of time and detected.

The explanation of the initial polarization state tracking of the polarization multiplexing self-homodyne detection system is as follows:

since the initialization phase defaults to the fact that the system has not yet started with real traffic data, the parameters of the polarization controller PC are also initial parameters, such asAnd theta₃Are all 0, i.e. the azimuth angle of the equivalent Jones matrix of the polarization controller PCAnd a phase difference theta₃Are all 0.

For the DC component of the I-path signalAnd the DC component of the Q-path signalDetecting, and calculating rotation matrix parameters theta and theta according to formula (1) and formula (2)Wherein, formula (1) and formula (2) are as follows:

the angles and phase differences, i.e. theta and phi, obtained according to equations (1) and (2)According to a plurality of possibleCombined regulation of polarization controllers PCAnd theta₃After each adjustment, the direct current component of the I path signal and the direct current component of the Q path signal are detectedAndwhether or not to be 0 at the same time untilAndwhile 0, the adjustment of the polarization controller PC is stopped

The explanation of the polarization state tracking process of the polarization multiplexing self-homodyne detection system is as follows:

now the parameters of the current known polarization controller PCAnd theta₃Of the specific values of (a) to (b),

for the DC component of the I-path signalAnd the DC component of the Q-path signalDetecting, and calculating rotation matrix parameters theta and theta according to formula (3) and formula (4)Wherein, formula (3) and formula (4) are as follows:

wherein the content of the first and second substances,from the direct component of the I-path signalAnd the DC component of the Q-path signalAnd theta obtained by predicting the rotation speed information of the optical fiber in the polarization stateThen adjusting the parameters of the polarization controller PC toAnd theta₃＝-θ。

Example 2

In other embodiments, in order to implement feedback control of the polarization controller PC, so as to output two optical signals without polarization crosstalk through the polarization beam splitter rotator PSR, the embodiment of the present application provides a new polarization multiplexing self-homodyne detection system based on fig. 2.

As shown in fig. 8, in the polarization multiplexing self-homodyne detection system of the embodiment of the present application, with respect to fig. 2, after the polarization splitting rotator PSR, two paths of light are respectively split by two power splitters PS (such as PS1 and PS2 shown in fig. 8) and are respectively sent to the optical mixers, and since one optical mixer already exists in fig. 2, but one optical mixer is introduced in the embodiment, in order to distinguish the two optical mixers, the original optical mixer is labeled as optical mixer 1, the newly added optical mixer is labeled as optical mixer 2, and the optical mixer 2 is respectively connected with two second balanced photodetectors (such as BPD3 and BPD4 shown in fig. 8).

Wherein, the calculation control unit acquires the direct current component of the I-path signal output by the second balanced photoelectric detector BPD3And the DC component of the Q-path signal output by the second balanced photodetector BPD4And calculating polarization state rotation information, and feeding back and controlling the polarization controller PC, so that two paths of optical signals without polarization crosstalk are output through the polarization beam splitting rotator PSR.

The principle of calculating the polarization rotation information by the calculation control unit and the method of adjusting the polarization controller PC are the same as those in the above example, and are not described herein again.

Example 3

As shown in fig. 9, in the polarization multiplexing self-homodyne detection system according to the embodiment of the present application, with respect to fig. 2, four paths of light are respectively split by four power splitters after an optical mixer, two second balanced photodetectors (such as the BPD3 and the BPD4 shown in fig. 9) are optically connected to the four paths of light, and the calculation control unit collects the dc component of the I-path signal output by the second balanced photodetector BPD3DC component of Q-path signal output by second balanced photoelectric detector BPD4And calculates polarization state rotation information and feedback-controls the polarization controller PC so thatTwo paths of optical signals without polarization crosstalk are output through the polarization beam splitting rotator PSR.

Example 4

As shown in fig. 7, in the polarization multiplexing self-homodyne detection system of the embodiment of the present application, with respect to fig. 2, the two third balanced photodetectors in fig. 2 are adjusted to be two second balanced photodetectors (such as the BPD1 and the BPD2 shown in fig. 7).

Wherein, a second balanced photoelectric detector BPD1 is used for outputting the direct current component of the I path signal; the other second balanced photodetector BPD2 is used to output the dc component of the Q-path signal.

The calculation control unit acquires the direct current component of the I-path signal output by the second balanced photoelectric detector BPD1DC component of Q-path signal output by second balanced photoelectric detector BPD2And calculating polarization state rotation information, and feeding back and controlling the polarization controller PC, so that two paths of optical signals without polarization crosstalk are output through the polarization beam splitting rotator PSR.

The principle of calculating the polarization rotation information by the calculation control unit and the method of adjusting the polarization controller PC are the same as those of the above example, and are not described herein again.

Example 5

As shown in fig. 10, in the polarization multiplexing self-homodyne detection system of the embodiment of the present application, with respect to fig. 2, the two third balanced photodetectors after the optical mixer are adjusted to be two first balanced photodetectors (such as the BPD1 and the BPD2 shown in fig. 10), where the dc component output by the two first balanced photodetectors isAndand after the polarization beam splitting rotator PSR, a part of light is split from the x path by the beam splitter PS and input into the added photodetector PD, which is used for outputting the direct current component of the x path signal

The principle of the calculation control unit for specifically calculating the polarization state rotation information is as follows:

with respect to embodiment 1, in the present embodiment, at the start of the polarization state tracking phase, the direct current component may be based on the formula (1), the formula (2), and the formula (5) in the above exampleAnd a direct current component ofAnd a direct current componentCalculating the rotation matrix parameters theta andequations (1) and (2) are not repeated here, wherein equation (5) is as follows:

in the process of tracking the polarization state, the sum of the rotation matrix parameters theta and theta is calculated according to the formula (4) and the formula (6)Where equation (4) can be seen in the above example, equation (6) is as follows:

example 6

In other embodiments, in order to implement feedback and control of the polarization controller PC, so as to output two optical signals without polarization crosstalk through the polarization splitting rotator PSR, the embodiment of the present application provides a new polarization multiplexing self-homodyne detection system based on fig. 2.

As shown in fig. 11, in the polarization multiplexing self-homodyne detection system of the embodiment of the present application, with respect to fig. 2, the two third balanced photodetectors after the optical mixer are adjusted to be two first balanced photodetectors (such as the BPD1 and the BPD2 shown in fig. 11), where the dc component output by the two first balanced photodetectors isAndin the embodiment, after the polarization beam splitter rotator PSR, a part of light is split from the y path by the optical splitter PS and input to the added photodetector PD, which is used for outputting the dc component of the y path signal

The principle of the calculation control unit for specifically calculating the polarization state rotation information is as follows:

with respect to embodiment 1, in the present embodiment, at the start of the polarization state tracking phase, the direct current component may be based on the formula (1), the formula (2), and the formula (7) in the above exampleAnd a direct current component ofAnd a direct current componentCalculating the rotation matrix parameters theta andequations (1) and (2) are not repeated here, wherein equation (7) is as follows:

in the process of tracking the polarization state, the sum of the rotation matrix parameters theta and theta is calculated according to the formula (4) and the formula (8)Where equation (4) can be seen in the above example, equation (8) is as follows:

example 7

As shown in fig. 12, in the polarization multiplexing self-homodyne detection system of the embodiment of the present application, the polarization multiplexing self-homodyne detection systemFIG. 2, the two third balanced photodetectors after the optical mixer are adjusted to two first balanced photodetectors (such as BPD1 and BPD2 shown in FIG. 12), wherein the DC component of the two first balanced photodetectors output isAndand the present embodiment splits a part of light from the x and y paths, respectively, by the beam splitters PS (PS 1 and PS2 shown in fig. 12) after the polarization beam splitter rotator PSR, and inputs it into the added second balanced photodetector BPD3, which is the second balanced photodetector BPD3 for outputting a direct current componentAnd isIs the difference between the DC components of at least part of the optical signals separated from the x and y optical signals and output by the balanced photoelectric detector.

The principle of the calculation control unit for specifically calculating the polarization state rotation information is as follows:

with respect to embodiment 1, in the present embodiment, at the start of the polarization state tracking phase, the dc component may be based on the formula (1), the formula (2), and the formula (9) in the above exampleAnd a direct current component ofAnd a direct current componentCalculating the rotation matrix parameters theta andequations (1) and (2) are hereIt is not repeated, wherein, formula (9) is as follows:

in the process of tracking the polarization state, the sum of the rotation matrix parameters theta and theta is calculated according to the formula (4) and the formula (11)Wherein, formula (4) can be seen in the above example, and formula (10) is as follows:

example 8

As shown in fig. 13, in the polarization multiplexing self-homodyne detection system according to the embodiment of the present application, with respect to fig. 2, after the polarization splitting rotator PSR, two light paths are respectively branched by two power splitters PS (such as PS2 and PS3 shown in fig. 13) and respectively sent to the optical mixers, and since one optical mixer already exists in fig. 2, and one optical mixer is introduced in the embodiment, in order to distinguish the two optical mixers, the original optical mixer is labeled as optical mixer 1, the newly added optical mixer is labeled as optical mixer 2, and the optical mixer 2 is respectively connected with two second balanced photodetectors (such as BPD3 and BPD4 shown in fig. 13). In addition, a part of the light is split from the x-path by a splitter PS1 and input to an added photodetector PD for outputting the dc component of the x-path signal

Wherein the calculation control unitCollecting the direct current component of the I-path signal output by the second balanced photoelectric detector BPD3And the DC component of the Q-path signal output by the second balanced photodetector BPD4And the DC component of the x-path signal output by the photodetector PDAnd calculating polarization state rotation information, and feeding back and controlling the polarization controller PC, so that two paths of optical signals without polarization crosstalk are output through the polarization beam splitting rotator PSR.

Example 9

As shown in fig. 14, in the polarization multiplexing self-homodyne detection system according to the embodiment of the present application, with respect to fig. 2, after the polarization splitting rotator PSR, two light paths are respectively branched by two power splitters PS (such as PS2 and PS3 shown in fig. 14) and respectively sent to the optical mixers, and since one optical mixer already exists in fig. 2, and one optical mixer is introduced in the embodiment, in order to distinguish the two optical mixers, the original optical mixer is labeled as optical mixer 1, the newly added optical mixer is labeled as optical mixer 2, and the optical mixer 2 is respectively connected with two second balanced photodetectors (such as BPD3 and BPD4 shown in fig. 14). In addition, a part of the light is split from the y-path by a splitter PS1 and input to an added photodetector PD for outputting the dc component of the y-path signal

Wherein, the calculation control unit acquires the direct current component of the I-path signal output by the second balanced photoelectric detector BPD3And the DC component of the Q-path signal output by the second balanced photodetector BPD4And the direct current component of the y-path signal output by the photoelectric detector PDAnd calculating polarization state rotation information, and feeding back and controlling the polarization controller PC, so that two paths of optical signals without polarization crosstalk are output through the polarization beam splitting rotator PSR.

Example 10

As shown in fig. 15, in the polarization multiplexing self-homodyne detection system according to the embodiment of the present application, with respect to fig. 2, after the polarization splitting rotator PSR, two light paths are respectively branched by two power splitters PS (such as PS2 and PS4 shown in fig. 15) and respectively sent to the optical mixers, and since one optical mixer already exists in fig. 2, and one optical mixer is introduced in the embodiment, in order to distinguish the two optical mixers, the original optical mixer is labeled as optical mixer 1, the newly added optical mixer is labeled as optical mixer 2, and the optical mixer 2 is respectively connected with two second balanced photodetectors (such as BPD3 and BPD4 shown in fig. 15).In addition, a part of light is branched from the x path and the y path by the beam splitters PS1 and PS3, respectively, and inputted into the added second balanced photodetector BPD5, which is used for outputting a direct current component BPD5Wherein the direct current componentIs the difference between the DC components of at least part of the optical signals separated from the x-path signal and the y-path signal and output by the balanced photoelectric detector.

Wherein, the calculation control unit acquires the direct current component of the I-path signal output by the second balanced photoelectric detector BPD3And the DC component of the Q-path signal output by the second balanced photodetector BPD4And the DC component of the output of the second balanced photodetector BPD5And calculating polarization state rotation information, and feeding back and controlling the polarization controller PC, so that two paths of optical signals without polarization crosstalk are output through the polarization beam splitting rotator PSR.

For the balanced photodetector with the monitoring port (i.e. the first balanced photodetector), reference may be made to fig. 16, and for the specific principle, reference may be made to related technologies, which are not described herein again.

For the dc-coupled balanced photodetector (i.e., the second balanced photodetector) and the photodetector (e.g., the dc-coupled photodetector), reference may be made to fig. 17, and for the specific principle, reference may be made to related technologies, which are not described herein again.

According to another aspect of the embodiments of the present application, there is also provided an apparatus for demultiplexing polarization, including:

at least one processor; and

a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,

According to another aspect of the embodiments of the present application, there is also provided a communication apparatus, including:

the input interface is used for acquiring the direct current component of the receiving end signal;

logic circuitry configured to perform a method as described in any of the above embodiments, e.g., perform the method shown in fig. 3, to obtain polarization rotation information;

The reader should understand that in the description of this specification, reference to the description of the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, a division of a unit is merely a logical division, and an actual implementation may have another division, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed.

Units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiments of the present disclosure.

In addition, functional units in the embodiments of the present disclosure may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present disclosure may be substantially or partially contributed by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method of the embodiments of the present disclosure. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

It should also be understood that, in the embodiments of the present disclosure, the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure.

While the present disclosure has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

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