WO2022142695A1 - Optical communication device and system - Google Patents

Abstract

The present application relates to an optical communication device, comprising a first laser, a second laser, an optical path assembly, a first modulator, a second modulator, a polarization rotation beam combiner and a signal processor, wherein the first laser emits a first beam, the wavelength of which is a first wavelength, and the second laser is used for emitting a second beam, the wavelength of which is a second wavelength; the optical path assembly outputs part of the first beam to the first modulator, and outputs part of the second beam to the second modulator; the first modulator modulates a first electrical signal onto the part of the first beam, so as to obtain first signal light; the second modulator modulates a second electrical signal onto the part of the second beam, so as to obtain second signal light; the polarization rotation beam combiner performs polarization rotation beam combination on the first signal light and the second signal light, so as to obtain beam-combined signal light, and sends the beam-combined signal light to a second optical communication device; and the optical path assembly sends the other part of the first beam and the other part of the second beam to the second optical communication device.

Description

Optical Communication Equipment and Systems

This application claims the priority of the Chinese patent application with the application number 202011637731.9 and the application name "Optical Communication Equipment and System" filed with the State Intellectual Property Office of China on December 31, 2020, the entire contents of which are incorporated into this application by reference .

technical field

The present application relates to the field of optical communication, and in particular, to an optical communication device and system.

Background technique

A coherent transmission system is a data transmission system commonly used in the field of optical communication technology.

In a common coherent transmission system, the transmitter and the receiver are each provided with a laser. The transmitting end performs data modulation on a part of the continuous light emitted by the laser to obtain signal light and sends it to the receiving end. The sending end sends another part of the continuous light emitted by the laser to the receiving end as the local oscillator light. The receiving end is provided with a coherent receiver, which inputs the received signal light and the local oscillator light into the coherent receiver for coherent detection, and converts the optical signal into an electrical signal.

In the above transmission system, the local oscillator light also needs to be transmitted. Due to the optical fiber transmission loss and device insertion loss, when it reaches the coherent receiver at the receiving end, the power of the local oscillator light will be reduced, and the reduction of the power of the local oscillator light will limit the coherent transmission system. Transmission distance. If the above problems are solved by increasing the output power of the laser or integrating the optical amplifier, the cost will be greatly increased.

SUMMARY OF THE INVENTION

In view of this, embodiments of the present application disclose an optical communication device, an optical communication system, and an optical communication method.

In a first aspect, an embodiment of the present application discloses a first optical communication device, the first optical communication device includes a first laser, a second laser, an optical circuit component, a first modulator, a second modulator, and a polarization rotation beam combining The controller PRC and signal processor, where:

The first laser is used to emit a first light beam with a wavelength length of the first wavelength, and the second laser is used to emit a second light beam with a wavelength length of the second wavelength;

The optical path component is used for outputting a part of the first light beam of the first light beam to the first modulator, and outputting a part of the second light beam of the second light beam to the second modulator;

The first modulator is used for modulating the first electrical signal sent by the signal processor on a part of the first light beam to obtain the first signal light;

The second modulator is used for modulating the second electrical signal sent by the signal processor on a part of the second light beam to obtain the second signal light;

The polarization rotation beam combiner is used to perform polarization rotation and beam combination of the first signal light and the second signal light to obtain the combined signal light, and send the combined signal light to the second optical communication device at the opposite end;

The optical path assembly is also used for sending another part of the first light beam and another part of the second light beam to the second optical communication device.

In a possible implementation manner, the optical circuit component includes a first coupler, a second coupler and a wave combiner, wherein,

The first coupler is used for splitting a part of the first beam to output to the first modulator, and splitting another part of the first beam to output to the combiner;

The second coupler is used for splitting a part of the second beam to output to the second modulator, and splitting another part of the second beam to output to the combiner;

The wave combiner is used for combining another part of the first light beam and another part of the second light beam and sending it to the second optical communication device.

In a possible implementation manner, the optical path component includes a third coupler and a demultiplexer, wherein,

The third coupler is used to combine the first beam and the second beam, and then perform power splitting to obtain the third beam and the fourth beam, and send the fourth beam to the second optical communication device. The third beam includes a part of the first beam. a light beam and a part of the second light beam, the fourth light beam includes another part of the first light beam and another part of the second light beam;

The wave splitter is used for splitting the third light beam to obtain a part of the first light beam and a part of the second light beam, and sending a part of the first light beam to the first modulator and a part of the second light beam to the second modulator.

In a possible implementation manner, the first optical communication device further includes a coherent receiver, and the coherent receiver is configured to receive continuous optical or optical signals sent by the second optical communication device.

In a possible implementation manner, the first optical communication device further includes a first filter and a second filter;

The first filter is used for sending the combined signal light to the second optical communication device or sending the signal light sent by the second optical communication device to the coherent receiver;

The second filter is used to transmit another part of the first light beam and another part of the second light beam to the second optical communication device or to transmit the continuous light emitted by the second optical communication device to a coherent receiver.

In a second aspect, the embodiments of the present application disclose another first optical communication device, the first optical communication device includes a first laser, a second laser, a third laser, a fourth laser, an optical path component, a first modulator, The second modulator, the third modulator, the fourth modulator, the first phase shifter, the second phase shifter, the first wave combiner, the second wave combiner, the polarization rotation beam combiner, and the signal processor, wherein :

The first laser is used to emit a first beam with a wavelength of the first wavelength, the second laser is used to emit a second beam with a wavelength of the second wavelength, and the third laser is used to emit a third beam with a wavelength of the third wavelength , the fourth laser is used to emit a fourth light beam with a wavelength length of the fourth wavelength;

The optical path assembly is used for outputting a part of the first beam of the first beam to the first modulator, outputting a part of the second beam of the second beam to the second modulator, and outputting a part of the third beam of the third beam to the third modulator the device, and outputs a part of the fourth beam of the fourth beam to the fourth modulator;

The first modulator is used for modulating the first electrical signal sent by the signal processor on a part of the first light beam to obtain the first signal light;

The first phase shifter is used for phase shifting the first modulated optical signal;

The second modulator is used for modulating the second electrical signal sent by the signal processor on a part of the second light beam to obtain the second signal light;

The third modulator is used for modulating the third electrical signal sent by the signal processor on a part of the third light beam to obtain the third signal light;

The second phase shifter is used for phase shifting the third modulated optical signal;

The fourth modulator is used for modulating the fourth electrical signal sent by the signal processor on a part of the fourth light beam to obtain the fourth signal light;

The first multiplexer is used to perform wavelength division multiplexing on the phase-shifted first signal light and the second signal light to obtain a first multiplexed signal;

The second multiplexer is configured to perform wavelength division multiplexing on the phase-shifted third signal light and the fourth signal light to obtain a second multiplexed signal;

The polarization rotation beam combiner is used to perform polarization rotation and beam combination of the first combined wave signal and the second combined wave signal to obtain the combined beam signal light, and send the combined beam signal light to the second optical communication device at the opposite end;

The optical path assembly is also used for sending another part of the first light beam, another part of the second light beam, another part of the third light beam and another part of the fourth light beam to the second optical communication device.

In a possible implementation manner, the optical circuit component includes a first coupler, a second coupler, a third coupler, a fourth coupler, and a wave combiner, wherein,

The first coupler is used for receiving the first light beam, dividing a part of the first light beam and outputting it to the first modulator, and dividing another part of the first light beam and outputting it to the wave combiner;

The second coupler is used for receiving the second light beam, splitting a part of the second light beam and outputting it to the second modulator, and splitting another part of the second light beam and outputting it to the combiner;

The third coupler is used for receiving the third light beam, splitting a part of the third light beam and outputting it to the third modulator, and splitting another part of the third light beam and outputting it to the combiner;

the fourth coupler is used for receiving the fourth light beam, splitting a part of the fourth light beam and outputting it to the fourth modulator, and splitting another part of the fourth light beam and outputting it to the wave combiner;

The wave combiner is used for combining another part of the first light beam, another part of the second light beam, another part of the third light beam and another part of the fourth light beam to the second optical communication device.

In a possible implementation manner, the optical circuit component includes a fifth coupler, a sixth coupler, a first wave splitter, a second wave splitter and a wave combiner, wherein,

The fifth coupler is used for receiving the first beam and the second beam, and splitting a part of the first beam and a part of the second beam to the first wave splitter, and splitting another part of the first beam and another part of the second beam to the wave combiner ;

The sixth coupler is used for receiving the third beam and the fourth beam, and splitting a part of the third beam and a part of the fourth beam to the second wave splitter, and splitting another part of the third beam and another part of the fourth beam to the wave combiner ;

The wave combiner is used for combining another part of the first light beam, another part of the second light beam, another part of the third light beam and another part of the fourth light beam to the second optical communication device.

In a possible implementation manner, the first optical communication device further includes a coherent receiver, and the coherent receiver is configured to receive continuous optical or optical signals sent by the second optical communication device.

In a possible implementation manner, the first optical communication device further includes a first filter and a second filter;

The first filter is used for sending the combined signal light to the second optical communication device or sending the signal light sent by the second optical communication device to the coherent receiver;

The second filter is used to send another part of the first light beam, another part of the second light beam, another part of the third light beam and another part of the fourth light beam to the second optical communication device or the continuous light emitted by the second optical communication device to the coherent receiver.

In a third aspect, an embodiment of the present application further discloses an optical communication system, the optical communication system includes a first optical communication device and a second optical communication device, and a communication connection between the first optical communication device and the second optical communication device,

The first optical communication device is any one of the devices in the first aspect.

In a possible implementation manner, the second optical communication device includes a second signal processor and a second coherent receiver, and the second coherent receiver is configured to receive the combined beam signal light and the local oscillator light sent by the first optical communication device and combine them. The detection of coherent reception is performed, and the second signal processor is used for secondly processing the signal output by the coherent receiver.

The present application provides an optical communication system by using two lasers on the originating device and improving the signal modulation scheme of the optical communication device, thereby realizing the power enhancement of the signal light and the local oscillator light, and improving the output of the optical communication system power, and improve the receiving sensitivity of the optical communication system.

The first optical communication device provided by the present application uses at least two lasers, and the continuous light emitted by each laser enters a different modulator, so that the output power of the optical communication system is improved without increasing the output power of the laser. The power of the signal light and the local oscillator light is improved.

In a fourth aspect, an embodiment of the present application discloses an optical communication method, which is applied to a first optical communication device, and the method includes:

emit a first light beam with a wavelength length of a first wavelength, and emit a second light beam with a wavelength length of a second wavelength;

modulating the first electrical signal on a part of the first light beam split from the first light beam to obtain the first signal light;

modulating the second electrical signal on a part of the second light beam split from the second light beam to obtain a second signal light;

The first signal light and the second signal light are combined by polarization rotation to obtain the combined signal light;

sending the combined signal light to the second optical communication device;

and sending the other part of the first light beam and the other part of the second light beam to the second optical communication device.

In a possible implementation manner, the first optical communication device includes a first coupler, a second coupler, a first modulator and a second modulator, and modulates the first electrical signal in a part of the first light beam split from the first light beam. On a light beam, the first signal light is obtained, including:

The first coupler splits a part of the first beam from the first beam and outputs it to the first modulator, and the first modulator modulates the first electrical signal on the part of the first beam split from the first beam to obtain the first signal light ;

The second electrical signal is modulated on a part of the second light beam split from the second light beam to obtain the second signal light, including:

The second coupler splits a part of the second beam from the second beam and outputs it to the second modulator, and the second modulator modulates the second electrical signal on a part of the second beam split from the second beam to obtain the second signal light .

In a possible implementation manner, the first optical communication device includes a third coupler, a wave splitter, a first modulator and a second modulator, and modulates the first electrical signal in a part of the first light beam split from the first light beam. On the light beam, the first signal light is obtained, and the second electrical signal is modulated on a part of the second light beam split from the second light beam to obtain the second signal light, including:

The third coupler combines the first beam and the second beam, and then performs power splitting to obtain a third beam. The third beam includes a part of the first beam and a part of the second beam, and the demultiplexer divides the third beam. A part of the first light beam and a part of the second light beam are obtained, and a part of the first light beam is sent to the first modulator, and a part of the second light beam is sent to the second modulator, and the first modulator modulates the first electrical signal from the first light beam. The first signal light is obtained from a part of the first light beam that is branched out, and the second signal light is obtained by the second modulator modulating the second electrical signal on a part of the second light beam that is branched from the second light beam.

In a fifth aspect, the embodiment of the present application further discloses an optical communication method, which is applied to the first optical communication device, and the method includes:

A first light beam with a wavelength length of a first wavelength is emitted, a second light beam with a wavelength length of a second wavelength is emitted, a third light beam with a wavelength length of a third wavelength is emitted, and a fourth light beam with a wavelength length of the fourth wavelength is emitted;

modulating the first electrical signal on a part of the first light beam split from the first light beam to obtain the first signal light;

phase-shift the first signal light;

modulating the second electrical signal on a part of the second light beam split from the second light beam to obtain a second signal light;

modulating the third electrical signal on a part of the third light beam split from the third light beam to obtain a third signal light;

phase-shift the third signal light;

modulating the first electrical signal on a part of the fourth light beam split from the fourth light beam to obtain a fourth signal light;

combining the phase-shifted first signal light and the second signal light to obtain a first combined signal;

combining the phase-shifted third signal light and the fourth signal light to obtain a second combined signal;

Performing polarization-rotation beam combining on the first combined signal and the second combined signal to obtain combined signal light, and sending the combined signal light to the second optical communication device;

Another portion of the first light beam, another portion of the second light beam, another portion of the third light beam, and another portion of the fourth light beam are sent to the second optical communication device.

In a possible implementation manner, the first optical communication device includes a first coupler, a second coupler, a first modulator, and a second modulator, and modulates the first electrical signal on a part of the first light beam that is branched out. On the light beam, the first signal light is obtained, including:

The first coupler receives the first beam and splits a part of the first beam to output to the first modulator, and the first modulator modulates the first electrical signal on the part of the first beam split from the first beam to obtain the first signal light ;

The second electrical signal is modulated on a part of the second light beam split from the second light beam to obtain the second signal light, including:

The second coupler receives the second beam and splits a part of the second beam to output to the second modulator. The second modulator modulates the second electrical signal on a part of the second beam split from the second beam to obtain the second signal light ;

The third electrical signal is modulated on a part of the third light beam split from the third light beam to obtain the third signal light, including:

The third coupler receives the third beam and splits a part of the third beam to output to the third modulator, and the third modulator modulates the third electrical signal on a part of the third beam split from the third beam to obtain the third signal light ;

The fourth electrical signal is modulated on a part of the fourth light beam branched from the fourth light beam to obtain a fourth signal light, including:

The fourth coupler receives the fourth beam and splits a part of the fourth beam to output to the fourth modulator, and the fourth modulator modulates the fourth electrical signal on the fourth beam split from the fourth beam to obtain the fourth signal light .

The optical communication method provided in the present application is mainly used in an optical coherent system. By using at least two light beams with different wavelengths for modulation, the output power of the optical communication system is improved, and the power of signal light and local oscillator light is improved. Compared to existing solutions by directly boosting the power of a single beam, the cost is greatly reduced.

Description of drawings

FIG. 1 is a schematic structural diagram of an optical communication system disclosed in an embodiment of the application;

FIG. 2 is a schematic structural diagram of a first optical communication device 10 disclosed in an embodiment of the present application;

FIG. 3 is a schematic structural diagram of another first optical communication device 10 disclosed in an embodiment of the present application;

FIG. 4 is a schematic structural diagram of another optical communication system disclosed in an embodiment of the present application;

FIG. 5 is a schematic structural diagram of a first optical communication device 40 disclosed in an embodiment of the present application;

FIG. 6 is a schematic structural diagram of another first optical communication device 40 disclosed in an embodiment of the present application;

FIG. 7 is a schematic diagram of an optical communication method disclosed in an embodiment of the present application;

FIG. 8 is a schematic diagram of another optical communication method disclosed in an embodiment of the present application.

Detailed ways

The coherent optical receiving technical solution proposed in this application can be applied to different network scenarios, including but not limited to: backbone optical transmission network, optical access network, data center interconnection, short-distance optical interconnection, and wireless service fronthaul/backhaul. Specifically, the technical solutions proposed in the present application can be used for receiving-side devices corresponding to the above-mentioned different networks, or optical systems including receiving-side devices.

The embodiment of the present application provides an optical communication system, the optical communication system includes a first optical communication device 10 and a second optical communication device 20, and the first optical communication device 10 and the second optical communication device 20 are connected by an optical fiber. The structures of the first optical communication device 10 and the second optical communication device 20 and the connection mode between them can be shown in FIG. 1 , and the first optical communication device 10 and the second optical communication device 20 are respectively introduced below.

The first optical communication device 10

As shown in FIG. 1 , the first optical communication device 10 includes a laser 101 , a laser 102 , an optical circuit assembly 103 , a modulator 104 , a modulator 105 , a signal processor 106 and a PRC (Polarization Rotator and Combiner) 107 .

The laser 101 and the laser 102 can be DFB lasers or other lasers that can be adapted to this scenario. The power of the continuous light generated by each laser may be the same or different. _The wavelength of the continuous light emitted by the laser 101 is λ ₁ , and the wavelength _of the continuous light emitted by the laser 102 is λ ₂ . Now, the continuous light emitted by the laser 101 is the first light beam, and the continuous light emitted by the laser 102 is the second light beam. Generally, unmodulated light is called continuous light, and modulated light is called signal light.

The optical circuit assembly 103 may be a single device, such as a coupler, or an assembly composed of multiple devices, such as a combination of a wavelength division multiplexer, an optical splitter, or a wavelength demultiplexer. Whether it is a single device or an assembly, the optical circuit assembly 103 is used to realize that part of the first beam emitted by the laser 101 is sent to the modulator 104, part of the second beam emitted by the laser 102 is sent to the modulator 105, and another part of the first beam is sent to the modulator 105. One light beam and another part of the second light beam are sent to the second optical communication device 20 . Here, another part of the first light beam and another part of the second light beam are sent to the coherent receiver 208 of the second optical communication device 20 at the opposite end as local oscillator light.

The modulator 104 modulates a beam of electrical signals sent by the signal processor 106 on a part of the first light beam to generate the first signal light, and the modulator 105 modulates another beam of electrical signals sent by the signal processor 106 on a part of the second light beam to generate the first signal light. the second signal light.

The PRC 107 performs polarization rotation and beam combining of the first signal light and the second signal light to obtain the combined signal light, and sends the combined signal light to the coherent receiver 208 of the second optical communication device 20 at the opposite end. In the combined signal light, one of the first signal light and the second signal light after passing through the PRC107 is a TE polarization mode, and the other is a TM polarization mode. Generally speaking, in the coherent receiver of the second optical communication device 20 , the first signal light and the second signal light in the combined optical signal can be respectively coherently detected with the local oscillator light corresponding to their own wavelengths. For example, in the above solution, the wavelength of the first signal light is λ ₁ , then in the coherent receiving and detection process, the first signal light can be combined with the local oscillator light with the same wavelength of λ ₁ (that is, the above-mentioned another part of the first light beam). Beat frequency detection. PRC can be replaced by a combination of PBC (Polarization Beam Combiner, polarization rotation beam combiner) and PR (Polarization Rotator, polarization rotator) connections.

The first optical communication device 10 may also include a coherent receiver 108 . The coherent receiver is used to receive the local oscillator light or signal light sent by the second communication device 20 , and perform coherent reception and detection on the local oscillator light and the signal light, and enter the signal processor 106 for processing to obtain data.

The first optical communication device 10 may also include a filter 109 and a filter 110 . The filter 109 is used for sending the combined signal light to the second optical communication device 20 or sending the signal light emitted by the second optical communication device 20 to the coherent receiver 108 . The filter 110 is used to send another part of the first light beam and another part of the second light beam to the second optical communication device 20 or to send the continuous light emitted by the second optical communication device to the coherent receiver 108 . The filter 109 and the filter 110 are mainly used to enable the link between the first optical communication device 10 and the second optical communication device 20 to realize the function of single-fiber bidirectional.

The optical communication device provided by the above solution of the present application uses two lasers, and the continuous light emitted by each laser enters a different modulator, which improves the output power of the optical communication system without increasing the output power of the laser, and realizes the The power of the signal light and the local oscillator light is increased. The cost of increasing the output power of a laser is much higher than adding an existing laser.

The second optical communication device 20

The second optical communication device 20 is the opposite end device of the first optical communication device 10. Generally speaking, their structures are symmetrical to each other, and they transmit signal light and local oscillator light to each other. As shown in FIG. 1 , the second optical communication device 20 includes a laser 201 , a laser 202 , an optical circuit assembly 203 , a first modulator 204 , a second modulator 205 , a signal processor 206 , a PRC 207 and a coherent receiver 208 . Its functional configuration is the same as or similar to that of the device corresponding to the first optical communication device 10 . The second optical communication device 20 may also include a filter 209 and a filter 210 for realizing the function of single-fiber bidirectional.

It should be noted that the wavelengths of the laser 201 and the laser 202 may also be λ ₁ and λ ₂ respectively, that is, corresponding to the laser 101 and the laser 102 respectively. The wavelengths of the laser 201 and the laser 202 can also be set to λ ₃ and λ ₄ according to the scene, which do not correspond to the laser 101 and the laser 102 .

In some unidirectional transmission scenarios, the second optical communication device 20 may only include the coherent receiver 208 and the signal processor 206 . At this time, the second optical communication device 20 only receives the signal light and the local oscillator light sent from the first optical communication device 10, and does not send the signal light or the local oscillator light to the first optical communication device 10. Then in this scenario, the first optical communication device 10 does not need the coherent receiver 108 either.

To sum up, the present application provides an optical communication system, including a first optical communication device 10 and a second optical communication device 20, by using two lasers on the originating device and improving the signal modulation scheme of the optical communication device, The power of the signal light and the local oscillator light is improved, and the output power of the optical communication system is improved. In addition, two continuous beams of light are used for modulation at the same time, so that the coherent receiver in the second optical communication device 20 can receive two beams of signal light at the same time, each beam of signal light corresponds to a polarization state, and each beam of signal light is received in the coherent state. In the machine, the local oscillator light with the same wavelength as its own can perform coherent detection, and the power of the local oscillator light is improved, which further improves the receiving sensitivity of the optical communication system.

The present application also provides possible design structures of the optical path assembly 103 in the above embodiments. The related obvious changes actually made according to the design structure provided in this application are also within the protection scope of this application.

As shown in FIG. 2 , FIG. 2 is a structured optical path assembly 103 -A of an optical path assembly 103 provided in an embodiment of the present application. The optical path assembly 103 -A includes a coupler 1031 , a coupler 1032 and a wave combiner 1033 .

The coupler 1031 receives the first light beam with a wavelength of λ ₁ emitted by the laser 101 , and the coupler 1032 receives the second light beam with a wavelength of λ ₂ emitted by the laser 102 . The coupler 1031 splits the first light beam, outputs a part of the first light beam to the modulator 104 , and outputs the other part of the first light beam to the wave combiner 1033 . The coupler 1032 splits the second light beam, outputs a part of the second light beam to the modulator 105 , and outputs another part of the second light beam to the wave combiner 1033 . The splitting ratio of the coupler 1031 and the coupler 1032 can be set according to actual scene requirements.

The multiplexer 1033 multiplexes another part of the first light beam and another part of the second light beam and outputs it to the filter 110 or directly through an optical fiber. In a possible implementation, the combiner 1033 may be integrated with the filter 110 .

As shown in FIG. 3 , FIG. 3 is another structured optical path assembly 103 -B of the optical path assembly 103 provided in the embodiment of the application. The optical path assembly 103 -B includes a coupler 1035 and a demultiplexer 1036 .

The coupler 1035 receives the first beam with a wavelength of λ ₁ and the second beam with a wavelength of λ ₂ , and outputs a part of the first beam and a part of the second beam to the demultiplexer 1036, and the other part of the first beam and the other A portion of the second beam is output to filter 110 or directly through the fiber. The coupler 1035 may be a 2*2 coupler, ie, 2 input ports and 2 output ports.

The demultiplexer 1036 demultiplexes a part of the first beam and a part of the second beam, and outputs a part of the first beam to the modulator 104 and a part of the second beam to the modulator 105 .

The demultiplexer mentioned in this application may be a wavelength division multiplexer, and the wavelength multiplexer may be a wavelength division multiplexer.

The embodiment of the present application also provides another optical communication system, the optical communication system includes a first optical communication device 40 and a second optical communication device 50, and an optical fiber is used between the first optical communication device 40 and the second optical communication device 50 connect. The structures of the first optical communication device 40 and the second optical communication device 50 and the connection mode between them may be shown in FIG. 4 , and the first optical communication device 40 will be mainly introduced below.

first optical communication device 40

The first optical communication device 40 includes a laser 401, a laser 402, a laser 403, a laser 404, an optical circuit assembly 405, a modulator 406, a modulator 407, a modulator 408, a modulator 409, a phase shifter 410, a phase shifter 411, a A waver 412 , a wave combiner 413 , a PRC414 and a signal processor 415 .

The laser 401 , the laser 402 , the laser 403 and the laser 404 may be DFB lasers or other lasers that can be adapted to this scenario. The power of the continuous light generated by each laser may be the same or different. The wavelength of continuous light emitted by laser 401 is λ ₁ , the wavelength of continuous light emitted by laser 402 is λ ₂ , the wavelength of continuous light emitted by laser 403 is λ ₃ , and the wavelength of continuous light emitted by laser 404 is λ ₄ . λ ₁ , λ ₂ , λ ₃ and λ ₄ are generally different, and the difference between them should be set to be greater than a certain threshold according to actual scene requirements. In this embodiment, the continuous light emitted by the laser 401 is the first light beam, the continuous light emitted by the laser 402 is the second light beam, the continuous light emitted by the laser 404 is the third light beam, and the continuous light emitted by the laser 404 is the fourth light beam . Generally, unmodulated light is called continuous light, and modulated light is called signal light.

The optical circuit assembly 405 may be a single device, such as a coupler, or an assembly composed of multiple devices, such as a combination of a wavelength division multiplexer, an optical splitter, or a wavelength demultiplexer. Whether it is a single device or an assembly, the optical circuit assembly 405 is used to realize that part of the first beam emitted by the laser 401 is sent to the modulator 406, part of the second beam emitted by the laser 402 is sent to the modulator 407, and the first beam emitted by the laser 403 is sent to the modulator 407. A portion of the three beams is sent to modulator 408, a portion of the fourth beam from laser 404 is sent to modulator 409, and another portion of the first beam, another portion of the second beam, another portion of the third beam, and another portion of the first beam The four beams are sent to the second optical communication device 50 . Here, another part of the first light beam, another part of the second light beam, another part of the third light beam and another part of the fourth light beam are sent to the coherent receiver in the second optical communication device 50 at the opposite end as local oscillator light.

The modulator 406 modulates the first electrical signal sent by the signal processor 415 on a part of the first light beam to generate the first signal light, and the modulator 407 modulates the second electrical signal sent by the signal processor 415 on a part of the second light beam to generate the first signal light. Second signal light, the modulator 408 modulates the third electrical signal sent by the signal processor 415 on a part of the third light beam to generate the third signal light, and the modulator 409 modulates the fourth electrical signal sent by the signal processor 415 on a part of the fourth light beam A fourth signal light is generated on the light beam.

The phase shifter 410 phase-shifts the second signal light, and the phase shifter 411 phase-shifts the fourth signal light. Phase shifter 410 and phase shifter 411 may be 90 degree phase shifters.

The combiner 412 combines the first signal light and the phase-shifted second signal light to obtain a first combined signal, and the combiner 413 combines the third signal light and the phase-shifted fourth signal light. wave to obtain the second composite signal. The PRC414 performs polarization rotation and beam combining of the first combined signal and the second combined signal to obtain combined signal light, and sends the combined signal light to the coherent receiver of the second optical communication device 50 at the opposite end. After the combined signal light enters the coherent receiver of the second optical communication device 50 at the opposite end, the signal light of each wavelength included in the combined signal light is coherently beat frequency with the local oscillator light corresponding to its own wavelength. For example, in the above solution, the wavelength of the first signal light is λ ₁ , then in the process of coherent reception and detection, the first signal light can be combined with the local oscillator light with the same wavelength of λ ₁ (that is, the above-mentioned other part of the first light beam) Perform beat frequency detection. PRC can be replaced by a combination of PBC (Polarization Beam Combiner, polarization rotation beam combiner) and PR (Polarization Rotator, polarization rotator) connections.

The first optical communication device 40 may also include a coherent receiver 416 . The coherent receiver 416 is configured to receive the local oscillator light or the signal light sent by the second communication device 50 , perform coherent reception and detection on the local oscillator light and the signal light, and then input them to the signal processor 415 for processing to obtain data.

The first optical communication device 40 may also include a filter 417 and a filter 418 . The filter 417 is used for sending the combined signal light to the second optical communication device 50 and/or sending the signal light emitted by the second optical communication device 50 to the coherent receiver 416 . The filter 418 is used to transmit another portion of the first light beam and another portion of the second light beam to the second optical communication device 50 and/or to output the continuous light emitted by the second optical communication device 50 to the coherent receiver 416 . The filter 417 and the filter 418 are also inside the optical path assembly 405 or outside the optical path assembly 405 . The filter 417 and the filter 418 are mainly used to enable the link between the first optical communication device 40 and the second optical communication device 50 to realize the function of single-fiber bidirectional.

The optical communication device provided by the above solution of this application uses 4 lasers, and the continuous light emitted by each laser enters different modulators. On the basis of no need to increase the output power of the laser, the output power of the optical communication system is further improved, and the realization of The power of the signal light and the local oscillator light is increased. In addition, 4 beams of continuous light are used to modulate 4 channels of electrical signals at the same time, and the coherent receiver can receive 4 beams of signal light at the same time, which further improves the communication efficiency of the optical communication system.

The second optical communication device 50

The second optical communication device 50 is the opposite end device of the first optical communication device 40. Generally speaking, their structures are symmetrical to each other, and they transmit signal light and local oscillator light to each other. It is worth noting that the emission wavelengths of the four lasers of the second optical communication device 50 are the same as those of the four lasers of the first optical communication device 40 respectively, and the emission wavelengths of the four lasers of the second optical communication device 50 can also be the same as those of the first optical communication device 40. Each of the four lasers of an optical communication device 40 is different, which is not limited in this application, and can be set by itself according to the actual scene.

In some unidirectional transmission scenarios, the second optical communication device 50 may only include a coherent receiver and a signal processor. At this time, the second optical communication device 50 only receives the signal light and the local oscillator light sent from the first optical communication device 40 , and does not send the signal light or the local oscillator light to the first optical communication device 40 . Then in this scenario, the first optical communication device 40 does not need the coherent receiver 416 either.

To sum up, the present application provides an optical communication system, including a first optical communication device 40 and a second optical communication device 50, by using 4 lasers on the originating device and improving the signal modulation scheme of the optical communication device, The power enhancement of the signal light and the local oscillator light is realized, the output power of the optical communication system is improved, and the communication efficiency of the optical communication system is improved.

The present application provides possible design structures of the optical path assembly 405 in the above embodiments. The related obvious changes actually made according to the design structure provided in this application are also within the protection scope of this application.

As shown in FIG. 5, FIG. 5 is a structured optical path assembly 405-A of an optical path assembly 405 provided in an embodiment of the present application. The optical path assembly 405-A includes a coupler 4051, a coupler 4052, a coupler 4053, a coupler 4054 and a coupler Waver 4055.

The coupler 4051 receives the first beam with a wavelength of λ ₁ emitted by the laser 401, the coupler 4052 receives the second beam with a wavelength of λ ₂ emitted by the laser 402, and the coupler 4053 receives the wavelength of λ ₃ emitted by the laser 403. For the third light beam, the coupler 4054 receives the _fourth light beam with a wavelength of λ4 emitted by the laser 404 . The coupler 4051 splits the first light beam, outputs a part of the first light beam to the modulator 406 , and outputs the other part of the first light beam to the wave combiner 4055 . The coupler 4052 splits the second light beam, outputs a part of the second light beam to the modulator 407 , and outputs another part of the second light beam to the wave combiner 4055 . The coupler 4053 splits the third light beam, outputs a part of the third light beam to the modulator 408 , and outputs the other part of the third light beam to the wave combiner 4055 . The coupler 4054 splits the fourth light beam, outputs a part of the fourth light beam to the modulator 409 , and outputs the other part of the fourth light beam to the wave combiner 4055 . The splitting ratios of the coupler 4051, the coupler 4052, the coupler 4053, and the coupler 4054 can be set according to actual scene requirements.

The wave combiner 4055 combines another part of the first light beam, another part of the second light beam, another part of the third light beam and another part of the fourth light beam and then outputs it to the filter 418 or directly through an optical fiber. In one possible implementation, the combiner 4055 may be integrated with the filter 418 .

As shown in FIG. 6 , FIG. 6 is a structured optical path assembly 405-B of another optical path assembly 405 provided in this embodiment of the application. The optical path assembly 405-B includes a coupler 4056, a coupler 4057, a demultiplexer 4058, a demultiplexer 4059 and combiner 40510.

The coupler 4056 receives the first beam of wavelength λ ₁ and the second beam of wavelength λ ₂ , and outputs a part of the first beam and a part of the second beam to the demultiplexer 4058, and the other part of the first beam and the other A portion of the second beam is output to the combiner 40510 . The coupler 4057 receives the _third light beam with a wavelength of λ3 and the _fourth light beam with a wavelength of λ4, and outputs a part of the third light beam and a part of the fourth light beam to the demultiplexer 4059, and another part of the first light beam and another part of the fourth light beam. A portion of the second beam is output to the combiner 40510 . Coupler 4056 and coupler 4057 may be 2*2 couplers, ie 2 input ports and 2 output ports.

The wave combiner 40510 combines another part of the first light beam, another part of the second light beam, another part of the third light beam and another part of the fourth light beam and then outputs it to the filter 418 or directly through an optical fiber. In one possible implementation, the combiner 4010 may be integrated with the filter 418 .

The present application discloses an optical communication method, which is applied to a first optical communication device. As shown in FIG. 7 , the method includes:

S701. Send out a first light beam with a wavelength length of a first wavelength, and emit a second light beam with a wavelength length of a second wavelength.

S702, modulating the first electrical signal on a part of the first beam split from the first beam to obtain a first signal light; modulating the second electrical signal on a part of the second beam split from the second beam to obtain a second signal Light.

S703. Perform polarization rotation and beam combination of the first signal light and the second signal light to obtain the combined signal light.

S704. Send the combined signal light to the second optical communication device; and send another part of the first light beam and another part of the second light beam to the second optical communication device.

In a possible implementation manner, the modulating the first electrical signal on a part of the first beam split from the first beam to obtain the first signal light includes: splitting the first coupler from the first beam A portion of the first beam is output to the first modulator.

The modulating the second electrical signal on a part of the second light beam split from the second light beam to obtain the second signal light comprises: a second coupler splitting a part of the second light beam from the second light beam and outputting it to the second light beam Modulator.

In a possible implementation manner, the first electrical signal is modulated on a part of the first light beam split from the first light beam to obtain first signal light, and the second electrical signal is modulated on the second electrical signal from the second light beam. On a part of the second light beam split from the light beam, a second signal light is obtained, including:

The third coupler combines the first beam and the second beam, and then performs power splitting to obtain a third beam, and the third beam includes the part of the first beam and the part of the second beam; The third beam is demultiplexed to obtain the part of the first beam and the part of the second beam, and the part of the first beam is sent to the first modulator, and the part of the second beam is sent to the second modulator .

The present application also discloses an optical communication method, which is applied to the first optical communication device. As shown in FIG. 8 , the method includes:

S801. Send out a first light beam with a wavelength length of a first wavelength, emit a second light beam with a wavelength length of a second wavelength, emit a third light beam with a wavelength length of a third wavelength, and emit a fourth light beam with a wavelength length of a fourth wavelength.

S802, modulate a first electrical signal on a part of the first beam split from the first beam to obtain a first signal light; shift the phase of the first signal light; modulate a second electrical signal on a part split from the second beam On the second light beam, the second signal light is obtained; the third electrical signal is modulated on a part of the third light beam split from the third light beam to obtain the third signal light; the phase of the third signal light is shifted; the fourth electrical signal is modulated A fourth signal light is obtained on a part of the fourth light beam branched from the fourth light beam.

S803, combining the phase-shifted first signal light and the second signal light to obtain a first combined signal; combining the phase-shifted third signal light and the fourth signal light to obtain a second combined signal;

S804. Perform polarization and rotation beam combining on the first combined signal and the second combined signal to obtain combined signal light, and send the combined signal light to the second optical communication device; combine another part of the first beam and another part of the first beam The second light beam, another part of the third light beam and another part of the fourth light beam are sent to the second optical communication device.

In a possible implementation manner, another part of the first light beam, another part of the second light beam, another part of the third light beam and another part of the fourth light beam are sent to the second optical communication device.

The modulating the first electrical signal on a part of the first beam split from the first beam to obtain the first signal light includes: a first coupler receives the first beam and splits the part of the first beam output to the first modulator.

The modulating the second electrical signal on a part of the second beam split from the second beam to obtain the second signal light includes: a second coupler receives the second beam and splits a part of the second beam output to the second modulator.

The modulating the third electrical signal on a part of the third beam split from the third beam to obtain the third signal light includes: a third coupler receiving the third beam and splitting the part of the third beam output to the third modulator.

The modulating the first electrical signal on a part of the fourth beam split from the fourth beam to obtain the fourth signal light includes: a fourth coupler receives the fourth beam and splits a part of the fourth beam output to the fourth modulator.

In the above method embodiments shown in FIGS. 7 and 8 , the first optical communication device may specifically include the devices shown in the foregoing FIGS. 1 to 6 . These devices can perform the corresponding steps in the above method embodiments.

The optical communication method provided by the present application is mainly used in an optical coherent system. By using at least two light beams with different wavelengths for modulation, the output power of the optical communication system is improved, and the power of signal light and local oscillator light is improved.

The terms "first", "second", etc. in this application are used to distinguish similar objects, and are not necessarily used to describe a particular order or sequence, and it should be understood that the data so used may be interchanged under appropriate circumstances, so that herein The described embodiments can be implemented in an order not described herein. "And/or" is used to describe the association relationship of associated objects, indicating that there can be three kinds of relationships. For example, A and/or B can mean that A exists alone, A and B exist at the same time, and B exists alone.

It should also be noted that, unless otherwise specified, the specific description of some technical features in one embodiment may also be applied to explain the corresponding technical features mentioned in other embodiments.

Finally, it should be noted that the above is only the specific embodiment of the present application, and the protection scope of the present application is not limited to this. Or replacement should be covered within the protection scope of this application.

Claims (16)

1. A first optical communication device, characterized in that the first optical communication device includes a first laser, a second laser, an optical circuit assembly, a first modulator, a second modulator, a polarization rotation beam combiner, and a signal processor ,in:

   The first laser is used for emitting a first light beam with a wavelength length of a first wavelength, and the second laser is used for emitting a second light beam with a wavelength length of a second wavelength;

   the optical path assembly is configured to output a part of the first beam of the first beam to the first modulator, and output a part of the second beam of the second beam to the second modulator;

   The first modulator is configured to modulate the first electrical signal sent by the signal processor on the part of the first light beam to obtain the first signal light;

   The second modulator is configured to modulate the second electrical signal sent by the signal processor on the part of the second light beam to obtain a second signal light;

   The polarization rotation beam combiner is used to perform polarization rotation and beam combination of the first signal light and the second signal light to obtain the combined signal light, and send the combined signal light to the second optical communication of the opposite end equipment;

   The optical path assembly is further configured to send another part of the first light beam of the first light beam and another part of the second light beam of the second light beam to the second optical communication device.
2. The apparatus of claim 1, wherein the optical circuit assembly comprises a first coupler, a second coupler and a combiner, wherein,

   the first coupler is used for splitting the part of the first beam to output to the first modulator, and splitting the other part of the first beam to output to the combiner;

   the second coupler is used for splitting the part of the second beam to output to the second modulator, and splitting the other part of the second beam to output to the combiner;

   The wave combiner is configured to combine the other part of the first light beam and the other part of the second light beam to send to the second optical communication device.
3. The device of claim 1, wherein the optical path assembly comprises a third coupler and a demultiplexer, wherein,

   The third coupler is used to combine the first beam and the second beam, and then perform power splitting to obtain a third beam and a fourth beam, and send the fourth beam to the second beam an optical communication device, the third light beam includes the portion of the first light beam and the portion of the second light beam, and the fourth light beam includes the other portion of the first light beam and the other portion of the second light beam;

   The wave splitter is used for splitting the third light beam to obtain the part of the first light beam and the part of the second light beam, and sending the part of the first light beam to the first modulator, the part of the first light beam A second light beam is sent to the second modulator.
4. The device according to any one of claims 1 to 3, wherein the first optical communication device further comprises a coherent receiver, and the coherent receiver is configured to receive the continuous optical or optical signals sent by the second optical communication device. light signal.
5. The device of claim 4, wherein the first optical communication device further comprises a first filter and a second filter;

   The polarization rotation beam combiner is configured to send the combined signal light to the second optical communication device and/or send the signal light sent by the second optical communication device to the second optical communication device through the first filter coherent receiver;

   The optical circuit assembly is used for sending the other part of the first light beam and the other part of the second light beam to the second optical communication device and/or sending the second optical communication device through the second filter The continuous light is sent to the coherent receiver.
6. A first optical communication device, characterized in that the first optical communication device comprises a first laser, a second laser, a third laser, a fourth laser, an optical circuit component, a first modulator, a second modulator, a third laser Three modulators, a fourth modulator, a first phase shifter, a second phase shifter, a first wave combiner, a second wave combiner, a polarization rotation beam combiner, and a signal processor, wherein:

   The first laser is used for emitting a first light beam with a wavelength length of a first wavelength, the second laser is used for emitting a second light beam with a wavelength length of a second wavelength, and the third laser is used for emitting a wavelength length of the second light beam. A third light beam with three wavelengths, the fourth laser is used to emit a fourth light beam with a wavelength length of a fourth wavelength;

   The optical path assembly is configured to output a part of the first beam of the first beam to the first modulator, output a part of the second beam of the second beam to the second modulator, and output the first beam of the second beam to the second modulator. A portion of the third beam of the three beams is output to the third modulator, and a portion of the fourth beam of the fourth beam is output to the fourth modulator;

   The first modulator is configured to modulate the first electrical signal sent by the signal processor on the part of the first light beam to obtain the first signal light;

   the first phase shifter is used for phase shifting the first modulated optical signal;

   The second modulator is configured to modulate the second electrical signal sent by the signal processor on the part of the second light beam to obtain a second signal light;

   The third modulator is configured to modulate the third electrical signal sent by the signal processor on the part of the third light beam to obtain a third signal light;

   the second phase shifter is used for phase shifting the third modulated optical signal;

   The fourth modulator is configured to modulate the fourth electrical signal sent by the signal processor on the part of the fourth light beam to obtain fourth signal light;

   The first multiplexer is configured to perform wavelength division multiplexing on the phase-shifted first signal light and the second signal light to obtain a first multiplexed signal;

   The second multiplexer is configured to perform wavelength division multiplexing on the phase-shifted third signal light and the fourth signal light to obtain a second multiplexed signal;

   The polarization rotation beam combiner is used to perform polarization rotation and beam combining of the first combined wave signal and the second combined wave signal to obtain combined signal light, and send the combined signal light to the second terminal of the opposite end. Optical communication equipment;

   The optical path assembly is further configured to send the other part of the first light beam, another part of the second light beam, another part of the third light beam and another part of the fourth light beam to the second optical communication device.
7. The device of claim 6, wherein the optical circuit assembly comprises a first coupler, a second coupler, a third coupler, a fourth coupler and a combiner, wherein,

   the first coupler is configured to receive the first light beam, separate the part of the first light beam and output it to the first modulator, and separate the other part of the first light beam and output it to the wave combiner;

   the second coupler is configured to receive the second light beam, separate a part of the second light beam to output to the second modulator, and separate the other part of the second light beam to output to the wave combiner;

   the third coupler is configured to receive the third light beam, separate the part of the third light beam and output it to the third modulator, and separate the other part of the third light beam and output it to the wave combiner;

   the fourth coupler is configured to receive the fourth light beam, separate a part of the fourth light beam and output it to the fourth modulator, and separate the other part of the fourth light beam and output it to the wave combiner;

   The wave combiner is configured to combine the other part of the first light beam, the other part of the second light beam, the other part of the third light beam and the other part of the fourth light beam to the second optical communication device.
8. The device of claim 6, wherein the optical circuit assembly comprises a fifth coupler, a sixth coupler, a first wave splitter, a second wave splitter and a wave combiner, wherein,

   The fifth coupler is used for receiving the first beam and the second beam, and splitting the part of the first beam and the part of the second beam to the first wave splitter, and splitting the other beam a part of the first light beam and the other part of the second light beam to the combiner;

   The sixth coupler is used for receiving the third beam and the fourth beam, and splitting the part of the third beam and the part of the fourth beam to the second wave splitter, and splitting the other a portion of the third light beam and the other portion of the fourth light beam to the combiner;

   The wave combiner is configured to combine the other part of the first light beam, the other part of the second light beam, the other part of the third light beam and the other part of the fourth light beam to the second optical communication device.
9. The device according to any one of claims 1 to 3, wherein the first optical communication device further comprises a coherent receiver, and the coherent receiver is configured to receive the continuous optical or optical signals sent by the second optical communication device. light signal.
10. The device of claim 9, wherein the first optical communication device further comprises a first filter and a second filter;

    The first filter is used for sending the combined signal light to the second optical communication device or sending the signal light sent by the second optical communication device to the coherent receiver;

    The second filter is used for sending the other part of the first light beam, the other part of the second light beam, the other part of the third light beam and the other part of the fourth light beam to the second optical communication device or to the second optical communication device. Continuous light from the second optical communication device is sent to the coherent receiver.
11. An optical communication system, characterized in that the optical communication system includes a first optical communication device and a second optical communication device, and the first optical communication device and the second optical communication device are communicatively connected,

    The first optical communication device is as described in any one of claims 1 to 10.
12. An optical communication method, applied to a first optical communication device, characterized in that the method comprises:

    emit a first light beam with a wavelength length of a first wavelength, and emit a second light beam with a wavelength length of a second wavelength;

    modulating a first electrical signal on a part of the first light beam split from the first light beam to obtain a first signal light;

    modulating a second electrical signal on a part of the second light beam split from the second light beam to obtain a second signal light;

    The first signal light and the second signal light are combined by polarization rotation to obtain the combined signal light;

    sending the combined signal light to a second optical communication device;

    Another part of the first beam split from the first beam and another part of the second beam split from the second beam are transmitted to the second optical communication device.
13. The method of claim 12, wherein the first optical communication device comprises a first coupler, a second coupler, a first modulator and a second modulator, and the modulating the first electrical signal at The first signal light is obtained from a part of the first beam split from the first beam, including:

    The first coupler splits the part of the first light beam from the first light beam and outputs it to the first modulator, and the first modulator modulates the first electrical signal between the first light beam and the first light beam. obtaining the first signal light on a part of the separated first light beam;

    The modulating the second electrical signal on a part of the second light beam split from the second light beam to obtain the second signal light, including:

    The second coupler splits the part of the second light beam from the second light beam and outputs it to the second modulator, the second modulator modulates the second electrical signal between the second light beam and the second light beam The second signal light is obtained from a part of the split second light beam.
14. The method of claim 12, wherein the first optical communication device comprises a third coupler, a demultiplexer, a first modulator and a second modulator, and wherein the modulating the first electrical signal from A part of the first beam split from the first beam to obtain a first signal light, and a second electrical signal is modulated on a part of the second beam split from the second beam to obtain a second signal light, including:

    The third coupler combines the first light beam and the second light beam, and then performs power splitting to obtain a third light beam, and the third light beam includes the part of the first light beam and the part of the second light beam a beam, the wave splitter splits the third beam to obtain the part of the first beam and the part of the second beam, and sends the part of the first beam to the first modulator, the A portion of the second light beam is sent to the second modulator, and the first modulator modulates the first electrical signal on a portion of the first light beam split from the first light beam to obtain the first signal light , the second modulator modulates the second electrical signal on a part of the second light beam split from the second light beam to obtain the second signal light.
15. An optical communication method, applied to a first optical communication device, characterized in that the method comprises:

    A first light beam with a wavelength length of a first wavelength is emitted, a second light beam with a wavelength length of a second wavelength is emitted, a third light beam with a wavelength length of a third wavelength is emitted, and a fourth light beam with a wavelength length of the fourth wavelength is emitted;

    modulating a first electrical signal on a part of the first light beam split from the first light beam to obtain a first signal light;

    phase-shifting the first signal light;

    modulating a second electrical signal on a part of the second light beam split from the second light beam to obtain a second signal light;

    modulating a third electrical signal on a part of the third beam split from the third beam to obtain a third signal light;

    phase-shifting the third signal light;

    modulating the first electrical signal on a part of the fourth light beam split from the fourth light beam to obtain a fourth signal light;

    combining the phase-shifted first signal light and the second signal light to obtain a first combined signal;

    combining the phase-shifted third signal light and the fourth signal light to obtain a second combined signal;

    performing polarization-rotation beam combining on the first combined signal and the second combined signal to obtain combined signal light, and sending the combined signal light to a second optical communication device;

    Another portion of the first light beam, another portion of the second light beam, another portion of the third light beam, and another portion of the fourth light beam are sent to the second optical communication device.
16. The method of claim 15, wherein the first optical communication device comprises a first coupler, a second coupler, a first modulator, and a second modulator, and the modulating the first electrical signal at The first signal light is obtained from a part of the first light beam split from the first light beam, including:

    The first coupler receives the first light beam and splits the part of the first light beam and outputs it to the first modulator, and the first modulator modulates the first electrical signal on the first light beam obtaining the first signal light on a part of the separated first light beam;

    The modulating the second electrical signal on a part of the second light beam split from the second light beam to obtain the second signal light, including:

    The second coupler receives the second light beam and splits a part of the second light beam to output to the second modulator, and the second modulator modulates the second electrical signal on the second light beam obtaining the second signal light on a part of the split second light beam;

    The modulating the third electrical signal on a part of the third light beam split from the third light beam to obtain the third signal light, including:

    The third coupler receives the third light beam and splits a part of the third light beam and outputs it to the third modulator, where the third modulator modulates the third electrical signal on the third light beam obtaining the third signal light on a part of the separated third light beam;

    The fourth electrical signal is modulated on a part of the fourth light beam split from the fourth light beam to obtain a fourth signal light, including:

    The fourth coupler receives the fourth light beam and splits a part of the fourth light beam to output to the fourth modulator, and the fourth modulator modulates the fourth electrical signal on the fourth light beam The fourth signal light is obtained from a part of the fourth light beam that is separated.

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