阅读说明：本技术 双向光传输系统和双向光传输方法 (Two-way optical transmission system and bi-directional light transmissions pass method ) 是由 中村康平 于 2018-04-03 设计创作，主要内容包括：一种双向光传输系统包含：第一光传输线路,包含第一中继器(30A)；第二光传输线路,包含第二中继器(30B)；以及经由这些传输线路而彼此连接使得它们可彼此通信的C+L频带发射/接收装置(10、20)。C+L频带发射/接收装置(10)将C频带中的光信号发射到第一光传输线路并且将L频带中的光信号发射到第二光传输线路,并且C+L频带发射/接收装置(20)将C频带中的光信号发射到第二光传输线路并且将L频带中的光信号发射到第一光传输线路。第一中继器(30A)将经由第一光传输线路双向传播的C频带中的光信号以及L频带中的光信号彼此分离,并分别放大分离后的光信号,并且第二中继器(30B)将经由第二光传输线路双向传播的C频带中的光信号以及L频带中的光信号彼此分离,并分别放大分离后的光信号。以此方式,可以扩大传输容量并减轻传输特性的劣化。(A kind of two-way optical transmission system includes: the first optical transmission line includes the first repeater (30A)；Second optical transmission line, comprising the second repeater (30B)；And C+L band transmission/reception device (10,20) that they can communicate with one another is connected with each other such that via these transmission lines.C+L band transmission/reception device (10) is by the optical signal launch in C-band to the first optical transmission line and by the optical signal launch in L-band to the second optical transmission line, and C+L band transmission/reception device (20) is by the optical signal launch in C-band to the second optical transmission line and by the optical signal launch in L-band to the first optical transmission line.First repeater (30A) will be separated from each other via the optical signal in the optical signal and L-band in the C-band of the first optical transmission line two-way propagation, and amplify the optical signal after separation respectively, and the second repeater (30B) will be separated from each other via the optical signal in the optical signal and L-band in the C-band of the second optical transmission line two-way propagation, and the optical signal after amplification separation respectively.In this way, it is possible to expand transmission capacity and mitigate the deterioration of transmission characteristic.)

1. a kind of two-way optical transmission system, comprising:

First optical transmission line, including the first repeater；

Second optical transmission line, including the second repeater；And

First transmission/reception and the second transmission/reception, first transmission/reception and second transmitting/ Reception device is connected to each other via first optical transmission line and second optical transmission line, enables them to each other Communication, each of first transmission/reception and second transmission/reception are configured to emit and receive Optical signal in first band and different from the optical signal in the second band of the first band；Wherein

First transmission/reception is by the optical signal launch in the first band to first optical transmission line And by the optical signal launch in the second band to second optical transmission line,

Second transmission/reception is by the optical signal launch in the first band to second optical transmission line And by the optical signal launch in the second band to first optical transmission line,

First repeater will be believed via the light in the first band of the first optical transmission line two-way propagation Number and the second band in the optical signal be separated from each other, and respectively amplification separation after optical signal, and

Second repeater will be believed via the light in the first band of the second optical transmission line two-way propagation Number and the second band in the optical signal be separated from each other, and respectively amplification separation after optical signal.

2. two-way optical transmission system according to claim 1, wherein

First repeater includes:

First multi-branch transport route, first transmitted in a first direction including the optical signal in the wherein first band Image intensifer, the first direction are the sides from first transmission/reception towards second transmission/reception To；And

Second multi-branch transport route, second transmitted in a second direction including the optical signal in the wherein second band Image intensifer, the second direction are the sides from second transmission/reception towards first transmission/reception To second repeater includes:

Third multi-branch transport route transmits in this second direction including the optical signal in the wherein first band Third image intensifer；And

4th multi-branch transport route transmits in said first direction including the optical signal in the wherein second band 4th image intensifer.

3. two-way optical transmission system according to claim 2, wherein

First repeater includes the first photo-coupler and the second photo-coupler, first photo-coupler and second light Each of coupler includes first to third port and is configured to export from the second port from the first port The optical signal of input simultaneously exports the optical signal inputted from the second port from the third port,

Second repeater includes third photo-coupler and the 4th photo-coupler, the third photo-coupler and the 4th light Each of coupler includes first to third port and is configured to export from the second port from the first port The optical signal of input simultaneously exports the optical signal inputted from the second port from the third port,

One end of the first multi-branch transport route is optically coupled to the third port of first photo-coupler, and institute The other end for stating the first multi-branch transport route is optically coupled to the first port of second photo-coupler,

One end of the second multi-branch transport route is optically coupled to the first port of first photo-coupler, and institute The other end for stating the second multi-branch transport route is optically coupled to the third port of second photo-coupler,

One end of the third multi-branch transport route is optically coupled to the first port of the third photo-coupler, and institute The other end for stating third multi-branch transport route is optically coupled to the third port of the 4th photo-coupler,

One end of the 4th multi-branch transport route is optically coupled to the third port of the third photo-coupler, and institute The other end for stating the 4th multi-branch transport route is optically coupled to the first port of the 4th photo-coupler,

First optocoupler is supplied to from the optical signal in the first band that first transmission/reception emits The second port of clutch,

The third optocoupler is supplied to from the optical signal in the second band that first transmission/reception emits The second port of clutch,

Second optocoupler is supplied to from the optical signal in the first band that second transmission/reception emits The second port of clutch, and

The 4th optocoupler is supplied to from the optical signal in the second band that second transmission/reception emits The second port of clutch.

4. two-way optical transmission system according to claim 3, wherein each of described first to fourth photo-coupler It is formed by optical circulator.

5. two-way optical transmission system according to claim 3, wherein each of described first to fourth photo-coupler By being configured to form the demultiplexer filter that the first band and the second band are separated from each other.

6. two-way optical transmission system according to any one of claim 1 to 5, wherein first transmission/reception Pseudo- light is inserted into the first band on the shortwave side of frequency band with each of second transmission/reception In at least one of described optical signal in the optical signal and the second band.

7. a kind of bi-directional light transmissions pass method, including by using the first optical transmission line for including the first repeater and including the Second optical transmission line of two repeaters is in a first direction and two direction of second direction opposite to the first direction uploads Optical signal in defeated first band and different from the optical signal in the second band of the first band, the bi-directional light transmissions pass Method further include:

It in said first direction, will by the optical signal launch in the first band to first optical transmission line The optical signal launch in the second band is incited somebody to action to second optical transmission line, and in first repeater Via in the first band of the first optical transmission line two-way propagation the optical signal and the second band in The optical signal be separated from each other, and respectively amplification separation after optical signal；And

It in this second direction, will by the optical signal launch in the first band to second optical transmission line The optical signal launch in the second band is incited somebody to action to first optical transmission line, and in second repeater Via in the first band of the second optical transmission line two-way propagation the optical signal and the second band in The optical signal be separated from each other, and respectively amplification separation after optical signal.

Technical field

The present invention relates to two-way optical transmission systems and bi-directional light transmissions pass method.

Background technique

Due to the current growth of communication service, need to realize large capacity optical transmission system.For example, in light undersea transmission system In, by using for increasing by reducing the interval between signal band to increase the method for the quantity of wavelength or for passing through The bit rate of each wave and the method for the transmission capacity that increases each wave realize high capacity transmission.However, using these methods The high capacity transmission of progress seems to be saturated.Therefore, it is necessary to further expansion transmission capacities.

Currently, in optical transmission system, optical signal is transmitted using C-band (traditional frequency bands).However, having studied except C frequency Also using L-band (long wavelength's frequency band) so as in future expansion transmission capacity except band.C-band is the frequency band around 1550nm, And L-band is the frequency band around 1580nm.

Fig. 1 shows the composition of the optical transmission system using C+L frequency band.This optical transmission system includes C+L frequency band repeater 100, C+L band transmission/reception device 110 and 120 and optical fiber 201 to 204.

C+L frequency band repeater 100 includes C-band repeater 101 and 102, L-band repeater 103 and 104, C/L frequency band letter Number demultiplexer 105 and 106 and C/L band signal multiplexer 107 and 108.C/L band signal demultiplexer 106 and 105 has There is mutually the same structure, and each of which has input port and the first output port and second output terminal Mouthful.C/L band signal multiplexer 107 and 108 has mutually the same structure, and each of which has the first input Port and the second input port and output port.

The input port of C/L band signal demultiplexer 105 is optically coupled to optical fiber 201.C/L band signal demultiplexer 106 input port is optically coupled to optical fiber 204.The output port of C/L band signal multiplexer 107 is optically coupled to optical fiber 202.The output port of C/L band signal multiplexer 108 is optically coupled to optical fiber 203.It should be noted that " optical coupled " expression light letter Number propagate in the case where not leading to substantial loss pass through coupling part.

The first output port and second output terminal mouth of C/L band signal demultiplexer 105 are distinguished via optical transmission line It is optically coupled to the first input port and the second input port of C/L band signal demultiplexer 107.C-band repeater 101 exists It is arranged in optical transmission line between first output port and first input port.L-band repeater 103 is in second output terminal mouth It is arranged in optical transmission line between the second input port.

The first output port and second output terminal mouth of C/L band signal demultiplexer 106 are distinguished via optical transmission line It is optically coupled to the first input port and the second input port of C/L band signal demultiplexer 108.C-band repeater 102 exists It is arranged in optical transmission line between first output port and first input port.L-band repeater 104 is in second output terminal mouth It is arranged in optical transmission line between the second input port.

C+L band transmission/reception device 110 includes C-band light emitting devices 111₁To 111_n, L-band light emitting devices 112₁To 112_n, C-band optical receiver apparatus 113₁To 113_n, L-band optical receiver apparatus 114₁To 114_n, C/L band wavelength multiplexing Unit 115 and C/L band wavelength separative unit 116.C+L band transmission/reception device 120 includes C-band light emitting devices 121₁To 121_n, L-band light emitting devices 122₁To 122_n, C-band optical receiver apparatus 123₁To 123_n, L-band optical receiver apparatus 124₁To 124_n, C/L band wavelength Multiplexing Unit 115 and C/L band wavelength separative unit 126.

C-band light emitting devices 111₁To 111_nExport the optical signal with the wavelength different from each other in C-band.L-band Light emitting devices 112₁To 112_nExport the optical signal with the wavelength different from each other in L-band.The multiplexing of C/L band wavelength is single 115 pairs of member is from C-band light emitting devices 111₁To 111_nOptical signal in the C-band of output and from L-band light emitting devices 112₁To 112_nOptical signal in the L-band of output is multiplexed, and exports the optical signal through wavelength multiplexing in C+L frequency band.From The optical signal through wavelength multiplexing in C+L frequency band that C/L band wavelength Multiplexing Unit 115 exports is supplied to via optical fiber 201 C/L band signal demultiplexer 105.

The optical signal through wavelength multiplexing in C+L frequency band is separated into C-band by C/L band signal demultiplexer 105 The optical signal through wavelength multiplexing in optical signal and L-band through wavelength multiplexing.The optical signal through wavelength multiplexing in C-band Amplified by C-band repeater 101 and be then fed to the first input port of C/L band signal multiplexer 107.In L-band Optical signals L-band repeater 103 through wavelength multiplexing amplifies and is then fed to the second of C/L band signal multiplexer 107 Input port.C/L band signal multiplexer 107 is multiplexed the optical signal in the optical signal and L-band in C-band.C/L Band signal multiplexer 107 exports the optical signal through wavelength multiplexing in C+L frequency band.It is exported from C/L band signal multiplexer 107 C+L frequency band in the optical signal through wavelength multiplexing be supplied to C/L band wavelength separative unit 126 via optical fiber 202.

C/L band wavelength separative unit 126 separates the optical signal through wavelength multiplexing in C+L frequency band according to wavelength.C/L Optical signal in respective wavelength in C-band is supplied to C-band optical receiver apparatus 123 by band wavelength separative unit 126₁It arrives 123_n.Optical signal in respective wavelength in L-band is supplied to L-band optical receiver apparatus by C/L band wavelength separative unit 126 124₁To 124_n。

C-band light emitting devices 121₁To 121_nExport the optical signal with the wavelength different from each other in C-band.L-band Light emitting devices 122₁To 122_nExport the optical signal with the wavelength different from each other in L-band.The multiplexing of C/L band wavelength is single 125 pairs of member is from C-band light emitting devices 121₁To 121_nOptical signal through wavelength multiplexing in the C-band of output and from L-band Light emitting devices 122₁To 122_nThe optical signal through wavelength multiplexing in the L-band of output is multiplexed, and is exported in C+L frequency band The optical signal through wavelength multiplexing.The light through wavelength multiplexing from the C+L frequency band that C/L band wavelength Multiplexing Unit 125 exports Signal is supplied to C/L band signal demultiplexer 106 via optical fiber 204.

The optical signal through wavelength multiplexing in C+L frequency band is separated into C-band by C/L band signal demultiplexer 106 The optical signal through wavelength multiplexing in optical signal and L-band through wavelength multiplexing.The optical signal through wavelength multiplexing in C-band Amplified by C-band repeater 102 and be then fed to the first input port of C/L band signal multiplexer 108.In L-band Optical signals L-band repeater 104 through wavelength multiplexing amplifies and is then fed to the second of C/L band signal multiplexer 108 Input port.C/L band signal multiplexer 108 in the optical signal and L-band through wavelength multiplexing in C-band through wavelength The optical signal of multiplexing is multiplexed.C/L band signal multiplexer 108 exports the optical signal through wavelength multiplexing in C+L frequency band.From The optical signal through wavelength multiplexing in C+L frequency band that C/L band signal multiplexer 108 exports is supplied to C/L via optical fiber 203 Band wavelength separative unit 116.

C/L band wavelength separative unit 116 separates the optical signal through wavelength multiplexing in C+L frequency band according to wavelength.C/L Optical signal in respective wavelength in C-band is supplied to C-band optical receiver apparatus 113 by band wavelength separative unit 116₁It arrives 113_n.Optical signal in respective wavelength in L-band is supplied to L-band optical receiver apparatus by C/L band wavelength separative unit 116 114₁To 114_n。

In the above-mentioned optical transmission system using C+L frequency band, by optical fiber 201 and 202, C-band repeater 101, L-band It is to be used for upstream after the transmission line that device 103, C/L band signal demultiplexer 105 and L-band signal multiplexer 107 are formed The transmission line of transmission.Meanwhile by optical fiber 203 and 204, C-band repeater 102, L-band repeater 104, C/L band signal The transmission line that demultiplexer 106 and L-band signal multiplexer 108 are formed is the transmission line for downstream transmission.C+L frequency The optical signal in C-band and the light in L-band can be emitted by using upstream transmission route with transmission/reception 110 Signal.In addition, C+L band transmission/reception device 120 can emit the optical signal in C-band by using downstream transmission route And the optical signal in L-band.As described above, because C+L can be transmitted in two directions using the optical transmission system of C+L frequency band Optical signal in frequency band, so can increase compared to the optical transmission system for emitting/receiving optical signal by the way that C-band is used only Transmission capacity.

As another optical transmission system, patent document 1 discloses a kind of bidirectional wavelength division multiplexing (WDM) optical transmission system, wherein Bidirectional WDM optical transmission system executes bidirectional WDM optical transport by using an optical transmission line.This bidirectional WDM optical transmission system Include the first WDM optical transmitting set/receiver and the 2nd WDM optical transmitting set/receiver.First WDM optical transmitting set/receiver connects It receives the optical signal in C-band (frequency band of 1580nm) and emits the optical signal in L-band (frequency band of 1550nm).2nd WDM light Emitter/receiver receives the optical signal in L-band and emits the optical signal in C-band.

In this bidirectional WDM optical transmission system, the optical signal in L-band is transferred to from the first WDM optical transmitting set/receiver 2nd WDM optical transmitting set/receiver, and the optical signal in C-band is transferred to first from the 2nd WDM optical transmitting set/receiver WDM optical transmitting set/receiver.

As another optical transmission system, patent document 2 discloses a kind of single-fiber bidirectional optical Wavelength division multiplex transmission system, wherein single Fine bidirectional optical wavelength multiplex transmission system is emitted/is received the signal through wavelength multiplexing of upstream by using single optical transmission line And the signal through wavelength multiplexing in downstream.The frequency band of the signal through wavelength multiplexing of upstream is different from downstream through wavelength multiplexing Signal frequency band.

Citation list

Patent document

1: the H11-284576 Japanese Unexamined Patent Application Publication of patent document

2: the 2004-7146 Japanese Unexamined Patent Application Publication of patent document

Summary of the invention

Technical problem

However, optical transmission system shown in FIG. 1 has the following problems.

Each of C-band repeater 101 and 102 and L-band repeater 103 and 104 contain in its input optical signal Have with when the component of wavelength, cannot achieve satisfactory amplification characteristic outside frequency band.In order to inhibit outside this frequency band wavelength to putting The influence of big characteristic, each of C/L band signal demultiplexer 105 and 106 are used with guard band (not used frequency Band) it is set in the transmissison characteristic of boundary between the transmission peak wavelength range in the transmission peak wavelength range in C-band and L-band C/L demultiplexer filter.In this C/L demultiplexer filter, needing to set has the guard band of slightly larger width so as to the End the optical signal in L-band on one output port (C-band transmission port) side and in second output terminal mouth (L-band transmission end Mouthful) end optical signal in C-band on side.However, when setting has the guard band of big width, the wavelength frequency of main signal Band reduces.Therefore, transmission capacity reduces.

In addition, when the optical signal in L-band is maintained at the C-band transmission end of C/L band signal demultiplexer 105 and 106 When on mouthful side, occur in C/L band signal multiplexer 107 and 108 remaining optical signal in L-band with it is other in L-band The coherent crosstalk of optical signal multiplexing.Similarly, when the optical signal in C-band is maintained at 105 He of C/L band signal demultiplexer When on 106 L-band transmission port side, the remaining optical signal in C-band occurs in C/L band signal multiplexer 107 and 108 With the coherent crosstalk of other optical signals multiplexing in C-band.Because coherent crosstalk influences the transmission characteristic of optical signal thus, so institute The quality of received optical signal can reduce.

In patent document 1 in disclosed bidirectional WDM optical transmission system, the band of the optical signal emitted in the upstream direction Width is different from the bandwidth of the optical signal emitted on downstream direction.For example, using L-band in the upstream direction, and in downstream Side is used up C-band.In this situation, even if transmission capacity passes through for being increased by reducing the interval between signal band Method of quantity of big wavelength etc. expands, and the transmission capacity in updrift side can also only expand within the scope of L-band, and under The upward transmission capacity of roam all around the would can also only expand within the scope of C-band.Accordingly, it is considered to arrive the current growth of communication service, it is desirable to Further increase transmission capacity.

In patent document 2 in disclosed single-fiber bidirectional optical Wavelength division multiplex transmission system, emit in the upstream direction The bandwidth of optical signal is different from the bandwidth of the optical signal emitted on downstream direction.Therefore, occur with patent document 1 disclosed in System in the problem of occurring similar problem.

It is an object of the present invention to provide be able to solve the above problem and therefore expansion transmission capacity and mitigate transmission characteristic Deterioration two-way optical transmission system and bi-directional light transmissions pass method.

Solution to the problem

In order to achieve the above objectives, according to aspects of the present invention, following two-way optical transmission system is provided.That is, one Kind two-way optical transmission system includes:

First optical transmission line includes the first repeater；

Second optical transmission line includes the second repeater；And

First transmission/reception and the second transmission/reception, via the first optical transmission line and the second optical transmission line Road is connected to each other, so that they can communicate with one another, it is each in the first transmission/reception and the second transmission/reception It is a be configured to emit and receive first band in optical signal and different from the optical signal in the second band of first band； Wherein

First transmission/reception by the optical signal launch in first band to the first optical transmission line and by second frequency Optical signal launch in band to the second optical transmission line,

Second transmission/reception by the optical signal launch in first band to the second optical transmission line and by second frequency Optical signal launch in band to the first optical transmission line,

First repeater will be believed via the light in the first band of the first optical transmission line two-way propagation Number and the second band in the optical signal be separated from each other, and respectively amplification separation after optical signal, and

Second repeater will be believed via the light in the first band of the second optical transmission line two-way propagation Number and the second band in the optical signal be separated from each other, and respectively amplification separation after optical signal.

According to another aspect of the present invention, following bi-directional light transmissions pass method is provided.That is, bi-directional light transmissions pass method packet Containing being existed by using the first optical transmission line comprising the first repeater and the second optical transmission line comprising the second repeater The optical signal in first band is transmitted on first direction and the second direction opposite with first direction and is different from the first frequency Optical signal in the second band of band, bi-directional light transmissions pass method also includes:

It in a first direction, will be in second band by the optical signal launch in first band to the first optical transmission line Optical signal launch is to the second optical transmission line, will be via the two-way biography of the first optical transmission line and in the first repeater The optical signal in the first band and the optical signal in the second band broadcast are separated from each other, and are put respectively Optical signal after big separation；And

It in a second direction, will be in second band by the optical signal launch in first band to the second optical transmission line Optical signal launch is to the first optical transmission line, will be via the two-way biography of the second optical transmission line and in the second repeater The optical signal in the first band and the optical signal in the second band broadcast are separated from each other, and are put respectively Optical signal after big separation.

Advantageous effects of the invention

According to the present invention it is possible to expand transmission capacity and mitigate the deterioration of transmission characteristic.

Detailed description of the invention

Fig. 1 is the block diagram for showing the configuration example of the optical transmission system using C+L frequency band；

Fig. 2 is the block diagram for showing the composition of two-way optical transmission system of the first example embodiment according to the present invention；

Fig. 3 A is the schematic diagram for the operation for explaining the optical circulator execution of two-way optical transmission system as shown in Figure 2；

Fig. 3 B is the signal for the operation for explaining another optical circulator execution of two-way optical transmission system as shown in Figure 2 Figure；

Fig. 4 A is the signal for the operation for explaining the another optical circulator execution of two-way optical transmission system as shown in Figure 2 Figure；

Fig. 4 B is the signal for the operation for explaining the another optical circulator execution of two-way optical transmission system as shown in Figure 2 Figure；

Fig. 5 A is the signal for the operation for explaining the another optical circulator execution of two-way optical transmission system as shown in Figure 2 Figure；

Fig. 5 B is the signal for the operation for explaining the another optical circulator execution of two-way optical transmission system as shown in Figure 2 Figure；

Fig. 6 A is the signal for the operation for explaining the another optical circulator execution of two-way optical transmission system as shown in Figure 2 Figure；

Fig. 6 B is the signal for the operation for explaining the another optical circulator execution of two-way optical transmission system as shown in Figure 2 Figure；

Fig. 7 is the block diagram for showing the composition of two-way optical transmission system of the second example embodiment according to the present invention；And

Fig. 8 is the modified exemplary block diagram for showing two-way optical transmission system shown in Fig. 2.

Specific embodiment

Then, it will be described with reference to the accompanying drawings according to example embodiment of the present invention.

(first embodiment)

Fig. 2 is the block diagram for showing the composition of two-way optical transmission system of the first example embodiment according to the present invention.

Referring to Fig. 2, two-way optical transmission system includes C+L band transmission/reception device 10 and 20, C+L frequency band repeater 30 And optical fiber 201 to 204.C+L band transmission/reception device 10 is optically coupled in C+L frequency band via optical fiber 201 and 203 After device 30, and C+L band transmission/reception device 20 is optically coupled to C+L frequency band repeater 30 via optical fiber 202 and 204.

Optical fiber 201 and 202 forms the first optical transmission line, and optical fiber 202 and 203 forms the second optical transmission line.It answers Note that being referred to as updrift side from C+L band transmission/reception device 10 to C+L band transmission/reception device 20 direction.From C 20 to C+L band transmission of+L-band transmission/reception/reception device 10 direction is referred to as downstream direction.

C+L band transmission/reception device 10 via the first optical transmission line by the optical signal launch in C-band to C+L frequency Band transmission/reception 20, and via the second optical transmission line by the optical signal launch in L-band to C+L band transmission/connect Receiving apparatus 20.Meanwhile C+L band transmission/reception device 20 arrives the optical signal launch in L-band via the first optical transmission line C+L band transmission/reception device 10, and send out the optical signal launch in C-band to C+L frequency band via the second optical transmission line Penetrate/reception device 10.In the first optical transmission line, the optical signal in C-band is transmitted in the upstream direction, and in downstream direction Optical signal in upper transmission L-band.In the second optical transmission line, in the upstream direction transmit L-band in optical signal, and The optical signal in C-band is transmitted on downstream direction.

The structure of C+L band transmission/reception device equipment 10 and 20 and C+L frequency band repeater 30 is discussed in detail below At.

Firstly, detailed description C+L band transmission/reception device 10 composition.

C+L band transmission/reception device 10 includes C-band light emitting devices 11₁To 11_n, L-band light emitting devices 12₁It arrives 12_n, C-band optical receiver apparatus 13₁To 13_n, L-band optical receiver apparatus 14₁To 14_n, C-band wavelength multiplexing unit 15A, L-band Wavelength multiplexing unit 15B, C-band wavelength separated unit 16A, L-band wavelength separated unit 16B and optical circulator 17 and 18. The quantity " n " of the quantity of instruction device can be arbitrarily determined.

Each of C-band wavelength multiplexing unit 15A and L-band wavelength separated unit 16B via optical circulator 17 and It is optically coupled to optical fiber 201.Each of L-band wavelength multiplexing unit 15B and C-band wavelength separated unit 16A are via light Circulator 18 and be optically coupled to optical fiber 203.

The existing optical circulator for such as polarizing related optical circulator and polarization-independent optical circulator can be used as optical circulator 17 With 18.Related optical circulator is polarized to be arranged including, for example, Faraday rotator, with 45 ° of relative angle to clamp from its two sides The magnet of the circumference of two polarizers and covering Faraday rotator of Faraday rotator.Polarization-independent optical circulator includes Such as Faraday rotator, 1/2 wavelength plate, polarization beam apparatus, reflecting mirror etc..Because these optical circulators are well-known, So hereinafter only describing its operation, and save the description of its structure.

Fig. 3 A schematically shows the image for indicating the operation executed by optical circulator 17.As shown in Figure 3A, optical circulator 17 include three port P1 to P3.In optical circulator 17, exported from the optical signal that port P1 is inputted from port P2.In addition, from The optical signal of port P2 input is exported from port P3.

The port P1 of optical circulator 17 is optically coupled to the output port of C-band wavelength multiplexing unit 15A.Optical circulator 17 Port P2 be optically coupled to one end of optical fiber 201.The port P3 of optical circulator 17 is optically coupled to L-band wavelength separated unit The input port of 16B.

Fig. 3 B schematically shows the image for indicating the operation executed by optical circulator 18.As shown in Figure 3B, it is similar to light Circulator 17, optical circulator 18 also include three port P1 to P3.In optical circulator 18, from port P1 input optical signal from Port P2 output.In addition, being exported from the optical signal that port P2 is inputted from port P3.

The port P1 of optical circulator 18 is optically coupled to the output port of L-band wavelength multiplexing unit 15B.Optical circulator 18 Port P2 be optically coupled to one end of optical fiber 203.The port P3 of optical circulator 18 is optically coupled to C-band wavelength separated unit The input port of 16A.

C-band light emitting devices 11₁To 11_nExport the optical signal with the wavelength different from each other in C-band.C-band wave Long Multiplexing Unit 15A is to from C-band light emitting devices 11₁To 11_nThe optical signal with respective wavelength of output is multiplexed, and Export the optical signal through wavelength multiplexing in C-band.The signal through wavelength multiplexing in C-band is supplied via optical circulator 17 To optical fiber 201.

L-band light emitting devices 12₁To 12_nExport the optical signal with the wavelength different from each other in L-band.L-band wave Long Multiplexing Unit 15B is to from L-band light emitting devices 12₁To 12_nThe optical signal with respective wavelength of output is multiplexed, and Export the optical signal through wavelength multiplexing in L-band.The signal through wavelength multiplexing in L-band is supplied via optical circulator 18 To optical fiber 203.

C-band wavelength separated unit 16A via optical circulator 18 and from optical fiber 203 receive C-band in through wavelength multiplexing Optical signal.C-band wavelength separated unit 16A separated according to wavelength in C-band it is received through wavelength multiplexing light letter Number, and the optical signal after the separation with respective wavelength is supplied to C-band optical receiver apparatus 13₁To 13_n。

L-band wavelength separated unit 16B via optical circulator 17 and from optical fiber 201 receive L-band in through wavelength multiplexing Optical signal.L-band wavelength separated unit 16B separated according to wavelength in L-band it is received through wavelength multiplexing light letter Number, and the optical signal after the separation with respective wavelength is supplied to L-band optical receiver apparatus 14₁To 14_n。

Then, C+L band transmission/reception device 20 composition is described in detail.

C+L band transmission/reception device 20 includes C-band light emitting devices 21₁To 21_n, L-band light emitting devices 22₁It arrives 22_n, C-band optical receiver apparatus 23₁to 23_n, L-band optical receiver apparatus 24₁To 24_n, C-band wavelength multiplexing unit 25A, L-band Wavelength multiplexing unit 25B, C-band wavelength separated unit 26A, L-band wavelength separated unit 26B and optical circulator 27 and 28. The quantity " n " of the quantity of instruction device can be arbitrarily determined.However, it is necessary to make the device in C+L band transmission/reception device 10 Quantity is equal to the quantity of the device in C+L band transmission/reception device 20.

Each of C-band wavelength multiplexing unit 25A and L-band wavelength separated unit 26B via optical circulator 27 and It is optically coupled to optical fiber 202.Each of L-band wavelength multiplexing unit 25B and C-band wavelength separated unit 26A are via light Circulator 28 and be optically coupled to optical fiber 204.

The existing optical circulator for such as polarizing related optical circulator and polarization-independent optical circulator can be used as optical circulator 27 With 28.The operation executed by optical circulator is hereinafter only described, and saves the description of its structure.

Fig. 4 A schematically shows the image for indicating the operation executed by optical circulator 27.As shown in Figure 4 A, optical circulator 27 also include three port P1 to P3.In optical circulator 27, exported from the optical signal that port P1 is inputted from port P2.In addition, It is exported from the optical signal that port P2 is inputted from port P3.

The port P1 of optical circulator 27 is optically coupled to the output port of L-band wavelength multiplexing unit 25B.Optical circulator 27 Port P2 be optically coupled to optical fiber 201.The port P3 of optical circulator 27 is optically coupled to C-band wavelength separated unit 26A's Input port.

Fig. 4 B schematically shows the image for indicating the operation executed by optical circulator 28.As shown in Figure 4 B, optical circulator 28 also include three port P1 to P3.In optical circulator 28, exported from the optical signal that port P1 is inputted from port P2.In addition, It is exported from the optical signal that port P2 is inputted from port P3.

The port P1 of optical circulator 18 is optically coupled to the output port of C-band wavelength multiplexing unit 25A.Optical circulator 28 Port P2 be optically coupled to optical fiber 204.The port P3 of optical circulator 28 is optically coupled to L-band wavelength separated unit 26B's Input port.

C-band light emitting devices 21₁To 21_nExport the optical signal with the wavelength different from each other in C-band.C-band wave Long Multiplexing Unit 25A is to from C-band light emitting devices 21₁To 21_nThe optical signal with respective wavelength of output is multiplexed, and Export the optical signal through wavelength multiplexing in C-band.The signal through wavelength multiplexing in C-band is supplied to via optical circulator 28 Optical fiber 204.

L-band light emitting devices 22₁To 22_nExport the optical signal with the wavelength different from each other in L-band.L-band wave Long Multiplexing Unit 25B is to from L-band light emitting devices 22₁To 22_nThe optical signal with respective wavelength of output is multiplexed, and Export the optical signal through wavelength multiplexing in L-band.The signal through wavelength multiplexing in L-band is supplied via optical circulator 27 To optical fiber 202.

C-band wavelength separated unit 26A via optical circulator 27 and from optical fiber 202 receive C-band in through wavelength multiplexing Optical signal.C-band wavelength separated unit 26A separated according to wavelength in C-band it is received through wavelength multiplexing light letter Number, and the optical signal after the separation with respective wavelength is supplied to C-band optical receiver apparatus 23₁To 23_n。

L-band wavelength separated unit 26B via optical circulator 28 and from optical fiber 204 receive L-band in through wavelength multiplexing Optical signal.L-band wavelength separated unit 26B separated according to wavelength in L-band it is received through wavelength multiplexing light letter Number, and the optical signal after the separation with respective wavelength is supplied to L-band optical receiver apparatus 24₁To 24_n。

C+L frequency band repeater 30 includes the first repeater units 30A and the setting being arranged between optical fiber 201 and 202 The second repeater units 30B between optical fiber 203 and 204.

Then, the composition of C+L frequency band repeater 30 is described in detail.

First repeater units 30A includes C-band repeater 31, L-band repeater 32 and optical circulator 35 and 36.

C-band repeater 31 is the image intensifer for amplifying the optical signal in C-band.The input port of C-band repeater 31 Optical fiber 201 is optically coupled to via optical circulator 35.The output port of C-band repeater 31 optics via optical circulator 36 It is coupled to optical fiber 202.For example, the image intensifer of such as er-doped fibre amplifier (EDFA) can be used as C-band repeater 31.

L-band repeater 32 is the image intensifer for amplifying the optical signal in L-band.The input port of L-band repeater 32 Optical fiber 202 is optically coupled to via optical circulator 36.The output port of L-band repeater 32 optics via optical circulator 35 It is coupled to optical fiber 201.For example, the image intensifer of such as EDFA can be used as L-band repeater 32.

The existing optical circulator for such as polarizing related optical circulator and polarization-independent optical circulator can be used as optical circulator 35 With 36.The operation executed by optical circulator is hereinafter only described, and saves the description of its structure.

Fig. 5 A schematically shows the image for indicating the operation executed by optical circulator 35.As shown in Figure 5A, optical circulator 35 include three port P1 to P3.In optical circulator 35, exported from the optical signal that port P1 is inputted from port P2.In addition, from The optical signal of port P2 input is exported from port P3.

The port P1 of optical circulator 35 is optically coupled to the output port of L-band repeater 32.The port of optical circulator 35 P2 is optically coupled to optical fiber 201.The port P3 of optical circulator 35 is optically coupled to the input port of C-band repeater 31.

Fig. 5 B schematically shows the image for indicating the operation executed by optical circulator 36.As shown in Figure 5 B, optical circulator 36 also include three port P1 to P3.In optical circulator 36, exported from the optical signal that port P1 is inputted from port P2.In addition, It is exported from the optical signal that port P2 is inputted from port P3.

The port P1 of optical circulator 36 is optically coupled to the output port of C-band repeater 31.The port of optical circulator 36 P2 is optically coupled to optical fiber 202.The port P3 of optical circulator 36 is optically coupled to the input port of L-band repeater 32.

In above-mentioned first repeater units 30A, from C-band wavelength multiplexing unit 15A export C-band in through wavelength The optical signal of multiplexing is supplied to the port P2 of optical circulator 35.Warp in optical circulator 35, from the C-band that port P2 is inputted The optical signal of wavelength multiplexing is exported from port P3.From in the C-band that the port P3 of optical circulator 35 is exported through wavelength multiplexing Optical signals C-band repeater 31 amplifies and is then fed to the port P1 of optical circulator 36.In optical circulator 36, from port The optical signal through wavelength multiplexing in the C-band of P1 input is exported from port P2.

Meanwhile light is supplied to from the optical signal through wavelength multiplexing in the L-band that L-band wavelength multiplexing unit 25B is exported The port P2 of circulator 36.In optical circulator 36, from the optical signal through wavelength multiplexing in the L-band that port P2 is inputted from end Mouth P3 output.The optical signals L-band repeater 32 through wavelength multiplexing from the L-band that the port P3 of optical circulator 36 is exported Amplify and be then fed to the port P1 of optical circulator 35.In optical circulator 35, from port P1 input L-band in through wave The optical signal of long multiplexing is exported from port P2.

Second repeater units 30B includes C-band repeater 33, L-band repeater 34 and optical circulator 37 and 38.

C-band repeater 33 is similar to C-band repeater 31.The input port of C-band repeater 33 is via optical circulator 37 and be optically coupled to optical fiber 203.The output port of C-band repeater 33 is optically coupled to optical fiber via optical circulator 38 204。

L-band repeater 34 is similar to L-band repeater 32.The input port of L-band repeater 34 is via optical circulator 38 and be optically coupled to optical fiber 204.The output port of L-band repeater 34 is optically coupled to optical fiber via optical circulator 37 203。

Such as polarize related optical circulator and the existing optical circulator of polarization-independent optical circulator can be used as optical circulator 37 With 38.The operation executed by optical circulator is hereinafter only described, and saves the description of its structure.

Fig. 6 A schematically shows the image for indicating the operation executed by optical circulator 37.As shown in Figure 6A, optical circulator 37 include three port P1 to P3.In optical circulator 37, exported from the optical signal that port P1 is inputted from port P2.In addition, from The optical signal of port P2 input is exported from port P3.

The port P1 of optical circulator 37 is optically coupled to the output port of C-band repeater 33.The port of optical circulator 37 P2 is optically coupled to optical fiber 203.The port P3 of optical circulator 37 is optically coupled to the input port of L-band repeater 34.

Fig. 6 B schematically shows the image for indicating the operation executed by optical circulator 38.As shown in Figure 6B, optical circulator 38 also include three port P1 to P3.In optical circulator 38, exported from the optical signal that port P1 is inputted from port P2.In addition, It is exported from the optical signal that port P2 is inputted from port P3.

The port P1 of optical circulator 38 is optically coupled to the output port of L-band repeater 34.The port of optical circulator 38 P2 is optically coupled to optical fiber 202.The port P3 of optical circulator 38 is optically coupled to the input port of C-band repeater 33.

In above-mentioned second repeater units 30B, from C-band wavelength multiplexing unit 25A export C-band in through wavelength The optical signal of multiplexing is supplied to the port P2 of optical circulator 38.Warp in optical circulator 38, from the C-band that port P2 is inputted The optical signal of wavelength multiplexing is exported from port P3.From in the C-band that the port P3 of optical circulator 38 is exported through wavelength multiplexing Optical signals C-band repeater 33 amplifies and is then fed to the port P1 of optical circulator 37.In optical circulator 37, from port The optical signal through wavelength multiplexing in the C-band of P1 input is exported from port P2.

Meanwhile light is supplied to from the optical signal through wavelength multiplexing in the L-band that L-band wavelength multiplexing unit 15B is exported The port P1 of circulator 37.In optical circulator 37, from the optical signal through wavelength multiplexing in the L-band that port P1 is inputted from end Mouth P2 output.The optical signals L-band repeater 34 through wavelength multiplexing from the L-band that the port P2 of optical circulator 37 is exported Amplify and be then fed to the port P1 of optical circulator 38.In optical circulator 38, from port P1 input L-band in through wave The optical signal of long multiplexing is exported from port P2.

Then, the operation by being executed according to the two-way optical transmission system of this example embodiment will be described in specific ways.

Firstly, description for transmitting the operation (upstream) of optical signal in the upstream direction.

In C+L band transmission/reception device 10, C-band wavelength multiplexing unit 15A exports multiple through wavelength in C-band Optical signal, and the optical signal through wavelength multiplexing in L-band wavelength multiplexing unit 15B output L-band.

From the optical signal through wavelength multiplexing in the C-band that C-band wavelength multiplexing unit 15A is exported via optical circulator 17 The first repeater 30A is supplied to optical fiber 201.The optical signal through wavelength multiplexing in the first repeater 30A, in C-band C-band repeater 31 is supplied to via optical circulator 35.The optical signals C-band repeater 31 through wavelength multiplexing in C-band Amplify and is then supplied to optical fiber 202 from optical circulator 36.

The optical signal through wavelength multiplexing in C-band is supplied to C+L band transmission/reception device 20 via optical fiber 202. In C+L band transmission/reception device 20, the optical signal through wavelength multiplexing in C-band is supplied to C via optical circulator 27 Band wavelength separative unit 26A.

Meanwhile from the optical signal through wavelength multiplexing in the L-band that L-band wavelength multiplexing unit 15B is exported via the ring of light Row device 18 and optical fiber 203 and be supplied to the second repeater 30B.In the second repeater 30B, in L-band through wavelength multiplexing Optical signal is supplied to L-band repeater 34 via optical circulator 37.The optical signals L-band through wavelength multiplexing in L-band Repeater 34 amplifies and is then supplied to optical fiber 204 from optical circulator 38.

The optical signal through wavelength multiplexing in L-band is supplied to C+L band transmission/reception device 20 via optical fiber 204. In C+L band transmission/reception device 20, the optical signal through wavelength multiplexing in L-band is supplied to L via optical circulator 28 Band wavelength separative unit 26B.

Then, the operation for uploading optical signals at downstream direction (Down stream) is described.

In C+L band transmission/reception device 20, C-band wavelength multiplexing unit 25A exports multiple through wavelength in C-band Optical signal, and the optical signal through wavelength multiplexing in L-band wavelength multiplexing unit 25B output L-band.

From the optical signal through wavelength multiplexing in the C-band that C-band wavelength multiplexing unit 25A is exported via optical circulator 28 The second repeater 30B is supplied to optical fiber 204.The optical signal warp through wavelength multiplexing in the second repeater 30B, in C-band C-band repeater 33 is supplied to by optical circulator 38.The optical signals C-band repeater 33 through wavelength multiplexing in C-band is put Greatly and optical fiber 203 then is supplied to from optical circulator 37.

The optical signal through wavelength multiplexing in C-band is supplied to C+L band transmission/reception device 10 via optical fiber 203.In In C+L band transmission/reception device 10, the optical signal through wavelength multiplexing in C-band is supplied to C-band via optical circulator 18 Wavelength separated unit 16A.

Meanwhile from the optical signal through wavelength multiplexing in the L-band that L-band wavelength multiplexing unit 25B is exported via the ring of light Row device 27 and optical fiber 202 are supplied to the first repeater 30A.The light through wavelength multiplexing in the first repeater 30A, in L-band Signal is supplied to L-band repeater 32 via optical circulator 36.The optical signals L-band relaying through wavelength multiplexing in L-band Device 32 amplifies and is then supplied to optical fiber 201 from optical circulator 35.

The optical signal through wavelength multiplexing in L-band is supplied to C+L band transmission/reception device 10 via optical fiber 201.In In C+L band transmission/reception device 10, the optical signal through wavelength multiplexing in L-band is supplied to L-band via optical circulator 17 Wavelength separated unit 16B.

Following functions and effect are provided according to the above-mentioned two-way optical transmission system of this example embodiment.In the following description, First optical transmission line is referred to as by the transmission line that optical fiber 201 and 202 and the first repeater 30A are formed.In addition, by optical fiber 203 and 204 and second repeater 30B formed transmission line be referred to as the second optical transmission line.

C+L band transmission/reception device 10 via the first optical transmission line by the optical signal launch in C-band to C+L frequency Band transmission/reception 20, and via the second optical transmission line by the optical signal launch in L-band to C+L band transmission/connect Receiving apparatus 20.Meanwhile C+L band transmission/reception device 20 arrives the optical signal launch in L-band via the first optical transmission line C+L band transmission/reception device 10, and send out the optical signal launch in C-band to C+L frequency band via the second optical transmission line Penetrate/reception device 10.

In the first optical transmission line, the optical signal in C-band is transmitted in the upstream direction, and transmit on downstream direction Optical signal in L-band.According to the light letter in the optical signal and L-band transmitted in the opposite direction in C-band as described above Number composition, the optical signal in optical signal and L-band in C-band can be by using optical circulator 35 and 36 without the use of C/ L demultiplexer filter and be separated from each other.In addition, because only the optical signal in C-band is supplied to C-band repeater 31, no It needs to end the optical signal in L-band in upstream transmission route on 31 side of C-band repeater.In addition, because only in L-band Optical signal be supplied to L-band repeater 32, so not needing to end in downstream transmission route on 32 side of L-band repeater Optical signal in C-band.Therefore, because have no need to ensure that guard band, thus do not occur the wavelength band of main signal due to Guard band and the problem of reduce.Therefore, according to the two-way optical transmission system of this example embodiment, with bi-directional light shown in FIG. 1 Transmission system is compared, and transmission capacity can expand.

In addition, optical signal in the C-band amplified by C-band repeater 31 and the L frequency amplified by L-band repeater 32 Optical signal in band transmits in directions opposite each other, and these optical signals are not re-used.According to above-mentioned configuration, do not occur The coherent crosstalk of one of the problem of as two-way optical transmission system shown in FIG. 1.Therefore, according to the bi-directional light of this example embodiment Transmission system, compared with two-way optical transmission system shown in FIG. 1, the deterioration of transmission characteristic be can reduce.

In the two-way optical transmission system according to this example embodiment, in optical circulator 17,18,27,28 and 35 to 38 Each is referred to alternatively as photo-coupler.C+L band transmission/reception device 10 and 20 can be known respectively as the first transmitting/reception dress It sets and the second transmission/reception.Is referred to alternatively as by the transmission line that optical fiber 201 and 202 and the first repeater 30A are formed One optical transmission line.In addition, being referred to alternatively as the second light by the transmission line that optical fiber 203 and 204 and the second repeater 30B are formed Transmission line.

In the first optical transmission line, C-band repeater 31 is referred to alternatively as the first image intensifer, and includes this C-band The transmission line of repeater 31 is referred to alternatively as the first multi-branch transport route.It is put in addition, L-band repeater 32 is referred to alternatively as the second light Big device, and include that the transmission line of this L-band repeater 32 is referred to alternatively as the second multi-branch transport route.

In the second optical transmission line, C-band repeater 33 is referred to alternatively as third image intensifer, and includes this C-band The transmission line of repeater 31 is referred to alternatively as third multi-branch transport route.It is put in addition, L-band repeater 34 is referred to alternatively as the 4th light Big device, and include that the transmission line of this L-band repeater 32 is referred to alternatively as the 4th multi-branch transport route.

(second embodiment)

Fig. 7 is the block diagram for showing the composition of two-way optical transmission system of the second example embodiment according to the present invention.

Two-way optical transmission system shown in Fig. 7, which has, to be similar to according to the two-way optical transmission system of the first example embodiment It constitutes, the difference is that two-way optical transmission system shown in Fig. 7 includes photo-coupler 45 to 48 to replace optical circulator 35 to arrive 38.It should be noted that only describing the part of the composition different from the first example embodiment, and save the description of same section.

Each of photo-coupler 45 to 48 includes three port P1 to P3.

In photo-coupler 45, port P1 is optically coupled to the output port of L-band repeater 32, and port P2 optics It is coupled to optical fiber 201.In addition, port P3 is optically coupled to the input port of C-band repeater 31.Photo-coupler 45 will be from C+L The signal through wavelength multiplexing in C-band that band transmission/reception device 10 exports is supplied to C-band repeater 31, and will be from L The signal through wavelength multiplexing in L-band that frequency band repeater 32 exports is supplied to C+L band transmission/reception device 10.

In photo-coupler 46, port P1 is optically coupled to the output port of C-band repeater 31, and port P2 optics It is coupled to optical fiber 202.In addition, port P3 is optically coupled to the input port of L-band repeater 32.Photo-coupler 46 will be from C+L The signal through wavelength multiplexing in L-band that band transmission/reception device 20 exports is supplied to L-band repeater 32, and will be from C The signal through wavelength multiplexing in C-band that frequency band repeater 31 exports is supplied to C+L band transmission/reception device 10.

In photo-coupler 47, port P1 is optically coupled to the input port of C-band repeater 33, and port P2 optics It is coupled to optical fiber 203.In addition, port P3 is optically coupled to the input port of L-band repeater 34.Photo-coupler 47 will be from C+L The signal through wavelength multiplexing in L-band that band transmission/reception device 10 exports is supplied to L-band repeater 34, and will be from C The signal through wavelength multiplexing in C-band that frequency band repeater 33 exports is supplied to C+L band transmission/reception device 10.

In photo-coupler 48, port P1 is optically coupled to the input port of C-band repeater 33, and port P2 optics It is coupled to optical fiber 204.In addition, port P3 is optically coupled to the output port of L-band repeater 34.Photo-coupler 48 will be from C+L The signal through wavelength multiplexing in C-band that band transmission/reception device 20 exports is supplied to C-band repeater 33, and will be from L The signal through wavelength multiplexing in L-band that frequency band repeater 34 exports is supplied to C+L band transmission/reception device 20.

It can be to the coupler that the optical signal in the optical signal and L-band in C-band is multiplexed or is demultiplexed for example The directional coupler of such as three-dB coupler can be used as photo-coupler 45 to 48.In this situation, photo-coupler 45 to 48 can be by C/ L demultiplexer filter is formed, but has no need to ensure that guard band.About C/L demultiplexer filter, for example, can be used using battle array The C/L demultiplexer filter of column waveguide optical grating (AWG) element is changed in a manner of continuous and is periodic using with refractive index The C/L demultiplexer filter of the multi-coated interference film made of semiconductor material of the periodic structure of change.

Function and effect similar to the first example embodiment is also provided according to the two-way optical transmission system of this example embodiment Fruit.

In the two-way optical transmission system according to this example embodiment, C+L band transmission/reception device 10 and 20 can also divide It Bei Chengwei not the first transmission/reception and the second transmission/reception.By optical fiber 201 and 202 and the first repeater 30A The transmission line of formation is referred to alternatively as the first optical transmission line.In addition, being formed by optical fiber 203 and 204 and the second repeater 30B Transmission line be referred to alternatively as the second optical transmission line.

In the first optical transmission line, C-band repeater 31 is referred to alternatively as the first image intensifer, and includes this C-band The transmission line of repeater 31 is referred to alternatively as the first multi-branch transport route.It is put in addition, L-band repeater 32 is referred to alternatively as the second light Big device, and include that the transmission line of this L-band repeater 32 is referred to alternatively as the second multi-branch transport route.

In the second optical transmission line, C-band repeater 33 is referred to alternatively as third image intensifer, and includes this C-band The transmission line of repeater 31 is referred to alternatively as third multi-branch transport route.It is put in addition, L-band repeater 34 is referred to alternatively as the 4th light Big device, and include that the transmission line of this L-band repeater 32 is referred to alternatively as the 4th multi-branch transport route.

Above-mentioned two-way optical transmission system according to respective examples embodiment is only the example of the disclosure.In addition, can be to above-mentioned The composition of two-way optical transmission system and operation carry out the intelligible modification and improvement of those skilled in the art, without departing from this hair Bright scope and spirit.

For example, light undersea transmission system is needed long-term such as 25 years or is more used long.However, the loss of optical signal is due to electricity Cable repairs and deteriorates and increase year after year.Therefore, in some cases, frequency spectrum deviation occurs.For example, spectral fluctuations occur, wherein Gain on the shortwave side of the wavelength region of main signal due to increase loss and increase.Therefore, flat gain characteristic is hateful Change.

According in the two-way optical transmission system of the first example embodiment or the second example embodiment, in order to reduce aforementioned frequency Spectrum fluctuation, can in C+L band transmission/reception device 10 and 20 by pseudo- light (dummy light) be inserted in C-band optical signal or On the shortwave side of each of L-band optical signal or C-band optical signal and L-band optical signal.

Fig. 8 shows the example for being inserted into the L-band optical signal of pseudo- light.This example corresponds to according to the first example embodiment Two-way optical transmission system.In C+L band transmission/reception device 10, L-band wavelength multiplexing unit 15B is exported on shortwave side It is inserted into the L-band optical signal of pseudo- light.In fig. 8, it is shown on top and is not inserted into the L-band optical signal of pseudo- light, and under Portion shows the L-band optical signal for being inserted into pseudo- light.

Increase from the gain on the shortwave side for the L-band optical signal (not having pseudo- light) that L-band repeater 34 exports, and Therefore flat gain characteristic deteriorates.By the way that pseudo- light is inserted on shortwave side outside L-band, the wave on its shortwave side can inhibit It is dynamic.

The C-band optical signal propagated in the upstream direction and the L-band optical signal upwardly propagated in downstream side are distinguished only It is vertical to be supplied to C-band repeater 31 and L-band repeater 32.The C-band optical signal that upwardly propagates in downstream side and in upstream The L-band optical signal just upwardly propagated is independently supplied to C-band repeater 33 and L-band repeater 34.Because being supplied to The optical signal of respective repeaters is separated from each other as described above, it is possible to be easy for the pseudo- light for being used to reduce frequency spectrum deviation to be inserted into C-band wavelength multiplexing unit 15A, L-band wavelength multiplexing unit 15B, C-band wavelength multiplexing unit 25A and L-band wavelength multiplexing In each of unit 25B.

The above-mentioned insertion of pseudo- light can be applied to the second example embodiment in a similar manner.

In addition, the quantity of C+L frequency band repeater 30 is unlimited in the two-way optical transmission system according to respective examples embodiment In one.Multiple C+L frequency band repeaters 30 can be arranged between C+L band transmission/reception device 10 and 20 via optical fiber.

The application based on and advocate on April 18th, 2017 filed in 2017-082077 Japanese patent application it is preferential Equity is weighed, the disclosure of the Japanese patent application is all incorporated herein by reference.

Reference signs list

10,20C+L band transmission/reception device

30C+L frequency band repeater

The first repeater of 30A

The second repeater of 30B