CN101494501A - Multi-code type light transmitter and method for generating optical signal - Google Patents

Abstract

The invention discloses a multi-code type optical transmitter and a method for generating optical signals, belonging to the field of optical communication. The transmitter includes: a precoding processing module and a modulator. The method includes: performing differential encoding on the data to be sent to generate two coded data; modulating the two coded data, and modulating the two coded data onto an optical signal to generate a CSRZ optical signal or an APRZ optical signal . In the present invention, by precoding the data to be sent and then modulating the coded data, both CSRZ optical signals and APRZ optical signals can be generated; at the same time, the quality of the generated APRZ optical signals is high; and the implementation is simple, While reducing the implementation complexity, the implementation cost is effectively reduced.

Description

Multi-code type optical transmitter and method for optical signal generation

technical field

The invention relates to the field of optical communication, in particular to a multi-code type optical transmitter and a method for generating optical signals.

Background technique

With the increase of communication capacity, especially the popularity of high-speed Ethernet and the development of multimedia services, high-speed optical fiber communication systems are becoming a research and commercial hotspot, and 40Gb/s systems have begun commercial use. Higher-speed communication systems, such as 100Gb /s Ethernet has also begun to enter the standardization stage. As the channel rate increases, some nonlinear impairments in the system channel, such as SPM (Self-Phase Modulation, self-phase modulation), IXPM (Intra-channel Cross-Phase Modulation, intra-channel cross-phase modulation) and IFWM (Intra- The influence of channel Four Wave Mixing, four-wave mixing in the channel, etc. has become more obvious, and has gradually become the main factor limiting system performance. SPM can broaden the spectrum and pulse of the signal, and overlap the frequency spectrum of adjacent channels in the DWDM (Dense Wavelength Division Multiplexing) system; IXPM makes the signal jitter in time, but its phase is not Sensitive, which can be effectively suppressed through proper dispersion management; unlike IXPM, IFWM is sensitive to phase, which can cause the amplitude of the signal to jitter and generate abnormal pulses.

The CSRZ (Carrier Suppressed Return-to-Zero, carrier suppressed return-to-zero code) optical signal has better performance against SPM, and has a higher dispersion tolerance; APRZ (Alternating Phase RZ, phase change return-to-zero code) optical signal can To effectively suppress the impact of IFWM, in order to modulate the transmitted data source into a CSRZ optical signal or APRZ optical signal, several optical transmitters have appeared in the prior art, which are briefly introduced as follows:

1. CSRZ Optical Signal Transmitter

Referring to the CSRZ optical signal transmitter shown in Figure 1, there are two series-connected MZMs (Mach-Zender Modulator, Mach-Zender Modulator) in the transmitter, which are MZM1 and MZM2 respectively. The generation process of the CSRZ optical signal is as follows:

First, the continuous light output by the laser is modulated by MZM 1 to output an optical pulse signal with frequency f, and the phase between adjacent pulses is reversed by 0 and π;

Wherein, the driving signal of the MZM1 is a radio frequency clock signal, the frequency of the radio frequency clock signal is 1/2 of the data rate (f) provided by the data source, the bias voltage of the MZM1 is set at the lowest point of the MZM1 transmission curve, when the When the amplitude of the added clock signal is V _π , where V _π is the half-wave voltage of the modulator, the duty cycle of the generated light pulse is 67%.

Then, the optical pulse signal passes through the MZM 2, and the MZM 2 modulates the data to be transmitted onto the optical pulse signal by adjusting the electrically adjustable delay line, thereby generating a CSRZ optical signal in which the adjacent bit phase is reversed to π.

2. APRZ Optical Signal Transmitter

Referring to the APRZ optical signal transmitter shown in Figure 2, the transmitter is mainly composed of three series-connected modulators, namely intensity modulator 1 (pulse signal generator), intensity modulator 2 (data modulator) and phase modulator device, the generation process of the APRZ optical signal is as follows:

1) The continuous light generated by the laser is modulated into a pulse signal by the intensity modulator 1;

Wherein, the driving signal of the intensity modulator 1 is a clock signal with a frequency f generated by the clock source 1. After passing through the intensity modulator 1, the continuous light becomes a periodically repeated pulse signal, and the frequency f of the pulse signal is the same as that sent by the data source. The rate f of the data is the same. According to needs, the pulse width of the pulse can be changed, and then the duty ratio of the finally generated APRZ optical signal can be determined.

2) The pulse signal is modulated by the data sent by the data source through the intensity modulator 2, the rate of the data signal is f, and an RZ (Return-to-Zero, return-to-zero code) optical signal with information is output;

Among them, the synchronization between the pulse signal and the data signal is realized by adjusting the electrically adjustable delay line 1, so that the intensity modulator 2 outputs the RZ optical signal with information, and the waveform of the signal is determined by the shape of the pulse generated by the intensity modulator 1. It is determined that the amplitude of the RZ optical signal is determined by the amplitude of the data to be sent by the data source. When sending '1', the amplitude is high and there is an optical pulse; when sending '0', the amplitude is low and there is no For light pulses, the phase of the RZ signal does not change and is a constant.

3) The phase modulator modulates the phase of the input RZ optical signal through the clock signal generated by the clock source 2 .

The frequency of this clock signal is half the data rate, which is f/2. By adjusting the electrically adjustable delay line 2, the maximum and minimum values of the clock signal amplitude are aligned with the data signal, so that the phase of the data signal is modulated and changes periodically, the period is 2 signal bits, and the phase of adjacent bits Different, there is a phase difference Δφ, as shown in Figure 3. By changing the amplitude of the drive signal (clock signal) of the phase modulator, the value of Δφ can be set to π/2 to generate an APRZ optical signal.

In the process of realizing the present invention, the inventor finds that the existing transmitter has at least the following problems:

Existing optical signal transmitters can only generate one type of optical signal, and the structure is relatively complex, using more optical devices, the system cost is relatively high, and the APRZ optical signal generated at the same time has poor ability to suppress nonlinear changes.

Contents of the invention

Embodiments of the present invention provide a multi-code type optical transmitter and a method for generating optical signals, which can simplify the structures of APRZ and CSRZ optical signal transmitters and suppress nonlinear damage of APRZ optical signals. Described technical scheme is as follows:

A kind of multicode type optical transmitter, described transmitter comprises:

The pre-coding processing module is used to perform differential coding on the data to be sent, generate coded data, and output the coded data in two ways;

a modulator, configured to receive an input optical signal and two channels of coded data output by the pre-coding processing module, modulate the two channels of coded data, modulate the two channels of coded data onto the optical signal, generate and Output carrier-suppressed return-to-zero code optical signal or phase change return-to-zero code optical signal.

Further, an embodiment of the present invention also provides a method for generating an optical signal, the method comprising:

Perform differential encoding on the data to be sent to generate two channels of encoded data;

The two channels of coded data are modulated, and the two channels of coded data are modulated onto an optical signal to generate a carrier suppression return-to-zero code optical signal or a phase change return-to-zero code optical signal.

Through the method provided in this embodiment, by precoding the data to be sent and then modulating the coded data, both CSRZ optical signals and APRZ optical signals can be generated; at the same time, the quality of the generated APRZ optical signals is high , and the implementation is simple, and the implementation cost is effectively reduced while reducing the implementation complexity.

Description of drawings

Fig. 1 is the structural representation of the CSRZ optical signal transmitter that prior art provides;

Fig. 2 is a schematic structural diagram of an APRZ optical signal transmitter provided by the prior art;

FIG. 3 is a schematic diagram of the APRZ optical signal waveform and phase provided by the prior art;

4 is a schematic structural diagram of a multi-code optical transmitter provided in Embodiment 1 of the present invention;

FIG. 5 is a schematic structural diagram of another multi-code optical transmitter provided in Embodiment 2 of the present invention;

FIG. 6 is a schematic structural diagram of an SSB modulator provided in Embodiment 2 of the present invention;

7 is a schematic diagram of converting an NRZ electrical signal into an RZ optical signal according to Embodiment 2 of the present invention;

FIG. 8 is a flow chart of a method for generating an optical signal according to Embodiment 3 of the present invention;

FIG. 9 is a schematic structural diagram of an SSB modulator provided in Embodiment 3 of the present invention.

Detailed ways

The embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

In the embodiment of the present invention, two channels of coded data are generated by performing differential encoding on the data to be transmitted; then the two channels of coded data are modulated, and the two channels of coded data are modulated onto the optical signal to generate a CSRZ optical signal or an APRZ optical signal, and the generated The quality of the APRZ optical signal is high; the implementation is simple, and the implementation cost is effectively reduced while reducing the implementation complexity.

Example 1

Referring to Fig. 4, an embodiment of the present invention provides a multi-code optical transmitter, which includes:

The precoding processing module 100 is configured to differentially encode the data to be transmitted, generate encoded data, and output the encoded data in two ways;

The modulator 200 is configured to receive the input optical signal and the two coded data output by the precoding processing module 100, modulate the two coded data, modulate the two coded data onto the optical signal, generate and output the CSRZ optical signal or APRZ light signal.

Wherein, the generation method of the two-way encoded data in this embodiment is to divide the data to be sent into two ways first, and then encode the two-way data respectively, as shown in FIG. 4 , the precoding processing module 100 in this way includes :

The demultiplexer 100a is used to convert the data to be sent into two paths of data through serial-to-parallel conversion, and output the two paths of data respectively;

The first precoder 100b is configured to receive one path of data output by the demultiplexer 100a, differentially encode one path of data, generate one path of encoded data, and output one path of encoded data;

The second precoder 100c is configured to receive another path of data output by the demultiplexer 100a, perform differential encoding on the other path of data, generate another path of encoded data, and output another path of encoded data.

Among them, the differential encoding of the data to be sent by the precoding processing module 100 is realized in the electrical domain. Encoding is similar to the encoding mechanism of DPSK (Differential Phase-shift Keying, differential phase-shift keying). The principle of this encoding method is that the original bit information before encoding is represented by the change of the two bit amplitudes before and after encoding, namely: When the original information is '0', the amplitude of the corresponding next bit after encoding is the same as that of the previous bit, for example, if the previous bit is '0', the next bit is still '0'; if the previous bit bit is '1', the next bit is still '1'. When the original information is '1', the magnitude of the corresponding next bit after encoding is different from that of the previous bit, that is, if the previous bit is '0', the next bit is '1'; if the previous bit is ' 1', the next bit is '0'. The encoded data rate remains unchanged, and it is an NRZ signal, and the bandwidth occupied does not change;

The above-mentioned demultiplexer 100a is the same as a common demultiplexer, that is, one high-speed signal is converted into two low-speed signals through serial-to-parallel conversion.

The transmitter provided in this embodiment can generate both a CSRZ optical signal and an APRZ optical signal by precoding the data to be transmitted and then modulating the encoded data;

At the same time, the phase difference between adjacent bits of the generated APRZ optical signal is abrupt, so the quality of the generated APRZ optical signal is high.

In addition, this embodiment uses fewer optoelectronic devices, has a compact structure, and is simple to implement, which effectively reduces the cost of the transmitter while reducing the volume of the system and the complexity of implementation.

Example 2

Referring to Fig. 5, the embodiment of the present invention provides another multi-code type optical transmitter, the transmitter includes: a precoding processing module 100 and a modulator 200, the precoding processing module 100 in this embodiment adopts the The data is encoded, and then the encoded data is divided into two paths. The pre-encoding processing module 100 specifically includes:

The precoder 100d is configured to differentially encode data to be transmitted, generate encoded data, and output encoded data;

The demultiplexer 100e is used to receive the encoded data output by the precoder 100d, convert the encoded data into two paths through serial-to-parallel conversion, and output the two paths of encoded data respectively;

The demultiplexer 100e has two output ports, respectively a first output port and a second output port, for outputting two coded data;

The modulator 200 is configured to receive the input optical signal and the two coded data output by the precoding processing module 100, modulate the two coded data, modulate the two coded data onto the optical signal, generate and output the CSRZ optical signal or APRZ light signal.

Wherein, the principle of differential encoding performed by the precoder 100d is the same as that in Embodiment 1, and will not be described in detail here.

Further, the precoding processing module 100 in the above-mentioned Embodiment 1 and Embodiment 2 also includes:

an amplifier, configured to amplify the generated encoded data, and output the amplified encoded data;

If the precoding processing module 100 has the structure shown in FIG. 4, two amplifiers are respectively arranged between the first precoder 100b and the modulator 200 and the second precoder 100c and the modulator 200, for converting the amplified The encoded data is sent to the modulator 200; if the precoding processing module 100 is the structure shown in Figure 5, then the two amplifiers are respectively arranged on the first output port of the demultiplexer 100e and the first output port of the modulator 200 and the demultiplexer 100e An amplifier is provided between the two output ports and the modulator 200, or between the precoder 100d and the demultiplexer 100e.

Further, the modulator 200 provided in Embodiment 1 and Embodiment 2 may be a SSB (Single Sideband, single sideband) modulator, referring to Fig. 6, the SSB modulator in this embodiment includes:

The above-mentioned SSB modulator can also be replaced by a DQPSK (Differential Quadrature Phase Shift Keying, differential quadrature phase shift keying) modulator, quadrature modulator or vector modulator, etc.

The optical signal input port 200a is used to receive the optical signal and divide the optical signal into two paths;

The first sub-modulator 200b is configured to receive one path of optical signal from the optical signal input port 200a and one path of coded data output by the precoding processing module 100, and modulate the one path of coded data to the above path under the action of the first bias voltage On the optical signal, generate the first return-to-zero signal and output the first return-to-zero signal;

The electrically adjustable delay line module 200c is configured to receive another path of coded data output by the precoding processing module 100, and to delay another path of coded data, so that the other path of coded data and the one path of coded data generate a predetermined length Time delay, the coded data after the output time delay; wherein, the time delay of the preset length can be T/2 that the coded data input to the second sub-modulator 200d is delayed compared with the coded data input to the first sub-modulator 200b, Wherein, T is the time occupied by one bit;

The second sub-modulator 200d is used to receive another optical signal from the optical signal input port 200a and the time-delayed encoded data output by the electrically adjustable delay line module 200c, and delay the time under the action of the second bias voltage Modulate the encoded data to another optical signal, generate the second return-to-zero code signal, and output the second return-to-zero code signal;

The combining module 200e is configured to receive the first return-to-zero code signal output by the first sub-modulator 200b and the second return-to-zero code signal output by the second sub-modulator 200d, and make The first return-to-zero code signal and the second return-to-zero code signal are combined to generate a CSRZ optical signal or an APRZ optical signal.

The above-mentioned first sub-modulator 200b and second sub-modulator 200d can be realized by MZM, and the first sub-modulator 200b and the second sub-modulator 200d receive coded data through the radio frequency signal input ports thereon. The performance of these two sub-modulators is exactly the same as that of the single-driver MZM, and it can work in different working states by setting the bias voltage. For example, when the bias voltage is at the highest point of the transmission curve, an RZ optical signal with a duty cycle close to 30% is generated; when the bias voltage is at the lowest point, a phase-shift keying signal is generated; when the bias voltage is at the quadrature point (middle point), an NRZ electrical signal is generated. In the embodiment of the present invention, the amplitudes of the radio frequency input port signals of the first sub-modulator 200b and the second sub-modulator 200d are set to 2V _π , where V _π is the half-wave voltage of the SSB modulator, and the first bias The voltage and the second bias voltage are set at the highest point of the transmission curve, so that the first sub-modulator and the second sub-modulator generate an RZ optical signal, and the information contained in this RZ optical signal is the data information before encoding, that is, in the automatic realization While converting NRZ electrical signals to RZ optical signals, decoding is realized in the optical domain;

The two RZ optical signals generated by the first sub-modulator 200b and the second sub-modulator 200d are combined in the form of time-division multiplexing in the combination module 200e of the modulator, and the output data rate after the combination is 2f, accounting for The empty ratio is close to 60%;

The phase difference of the optical signals on the two branches output by the first sub-modulator 200b and the second sub-modulator 200e can be precisely controlled by the third bias voltage of the modulator, so that the adjacent bits of the output signal can maintain a constant phase Differences, such as π, π/2, etc., to generate the required CSRZ optical signal or APRZ optical signal.

Referring to Figure 7, the NRZ electrical signal generated after encoding passes through an electrical amplifier, so that the amplitude of the output signal is about 2V _π , where V _π is the half-wave voltage of the SSB modulator. At this time, if the bias point of the MZM is set at the highest point of the transmission curve, then after passing through the MZM, an RZ optical signal with a duty cycle of about 30% is output. In addition, the content of the RZ optical signal is in one-to-one correspondence with the NRZ electrical signal before encoding. Assume that the bit information before encoding is '01110100', the bit information after encoding is '01011000', and the bit information generated after modulation is '01110100'.

In this embodiment, through the modulator provided in FIG. 6 , the coded data of the precoding processing module 100 are respectively loaded to the first sub-modulator 200b and the second sub-modulator 200d at a lower rate (for example, 20Gb/s), wherein one The encoded data passes through an electrically adjustable delay line module 200c, so that the two channels of data have a relative time delay of T/2, where T is the time occupied by one bit, for example: one bit period of 20Gb/s data. After modulation, the two MZMs respectively generate 20Gb/s RZ optical signals with a duty ratio of 30%. The phases of the signals are φ ₁ and φ ₂ respectively. After combining in time, the generated duty ratio is 60%. 40Gb/s RZ optical signal. By setting the size of the third bias voltage, there is a phase difference between the phases of the two 20Gb/s RZ optical signals, so that the generated 40Gb/s signal always maintains a constant phase difference between adjacent bits Δφ, such as π, π/2, etc., so as to generate the required CSRZ optical signal or APRZ optical signal.

The optical transmitter provided in this embodiment can generate both a CSRZ optical signal and an APRZ optical signal by precoding the data to be sent and then modulating the encoded data; while the CSRZ optical signal transmission in the prior art The machine can only generate CSRZ optical signals, but not APRZ optical signals;

At the same time, the phase difference between the adjacent bits of the generated APRZ optical signal is abrupt, so the quality of the generated APRZ optical signal is high; while the phase of the adjacent bits of the APRZ optical signal generated by the existing APRZ optical signal transmitter is in a sinusoidal manner Change, the change process is slow, it is a sinusoidal APRZ optical signal, not an APRZ optical signal in the strict sense, thus reducing the ability of the signal to suppress nonlinear changes.

Moreover, the optical transmitter provided by this embodiment uses fewer optoelectronic devices, has a compact structure, and is simple to implement. While reducing the system volume and implementation complexity, it effectively reduces the cost of the transmitter; while the optical transmitter in the prior art The implementation scheme of APRZ optical signal transmitter is generally more complicated, using many optoelectronic devices, and the system cost is high; for example, the APRZ transmitter shown in Figure 2 uses three modulators, which are used to generate optical pulse signals and modulate data respectively. And the modulation phase, in order to realize the synchronization of the modulation, two electrically adjustable delay lines need to be used, and a frequency divider (or frequency multiplier) is needed to generate two clock signals of different frequencies.

Example 3

This embodiment provides a method for generating an optical signal. The method performs differential encoding on the data to be sent to generate two channels of encoded data; then modulates the two channels of encoded data respectively, and modulates the two channels of encoded data onto the optical signal. Generate a CSRZ optical signal or an APRZ optical signal; referring to Figure 8, the method specifically includes:

Step 101: Perform differential encoding on the data to be sent to generate two channels of encoded data;

Among them, generating two-way encoded data can be achieved in two ways:

1) Convert the data to be sent into two channels of data through serial-to-parallel conversion, and then differentially encode the two channels of data to generate two channels of encoded data;

2) Perform differential encoding on the data to be sent to generate encoded data, and then convert the encoded data into two channels through serial-to-parallel conversion to obtain two encoded data;

Further, the generated two-way coded data can be appropriately amplified as required.

Step 102: Before modulating the data, make one channel of encoded data input to the modulator pass through an electrically adjustable delay line, and adjust the delay line so that a time delay of T/2 is generated between the two channels of encoded data input to the modulator, Where T is the time occupied by one bit.

Step 103: the modulator divides the received optical signal into two paths, and outputs them to the first sub-modulator and the second sub-modulator respectively;

Wherein, the modulator is composed of two sub-modulators placed in parallel, and is used to modulate the coded data on the two optical signals respectively.

Step 104: The first sub-modulator modulates one channel of coded data onto one channel of optical signal under the action of the first bias voltage to generate a first channel of return-to-zero code signal.

Step 105: The second sub-modulator modulates the time-delayed coded data onto another optical signal under the action of the second bias voltage to generate a second return-to-zero signal.

Step 106: The modulator combines the first return-to-zero code signal and the second return-to-zero code signal under the action of the third bias voltage to generate a CSRZ optical signal or an APRZ optical signal.

The order of the steps in the above method is not strictly limited, but is just marked for convenience of description, for example, the order of steps 104 and 105 can be exchanged.

The modulator in this embodiment takes the SSB modulator as an example. Referring to FIG. 9, the SSB modulator is similar to the SSB modulator provided in FIG. For A and B, the bias voltage of the whole SSB modulator is set to C, by adjusting the bias voltage C, the phase difference between the optical signals output by MZMA and MZMB can be changed. The data source of this embodiment takes the coded data of 20Gb/s as an example, and the time delay of preset length is generated between the coded data input into MZMA and MZMB through the electrically adjustable delay line. When modulating the data, the bias voltage A and B are set at the highest point of the MZMA and MZMB transmission curves, the optical signal output by each MZM after modulation is an RZ optical signal, the duty cycle is about 30%, and the data rate is f. The two RZ signals generated by MZMA and MZMB are combined in the form of time division multiplexing inside the SSB modulator. After the combination, the output data rate is 2f, and the duty cycle is close to 60%. By setting the bias voltage C, the adjacent bits of the output signal can maintain a constant phase difference, such as π, π/2, etc., so as to generate the required CSRZ optical signal or APRZ optical signal.

The method provided in this embodiment can generate both CSRZ optical signals and APRZ optical signals by precoding the data to be transmitted and then modulating the encoded data;

At the same time, the phase difference between the adjacent bits of the generated APRZ optical signal is in the form of a sudden change, so the quality of the generated APRZ optical signal is high;

Moreover, the implementation of this embodiment is simple, and while reducing the implementation complexity, the implementation cost is effectively reduced.

All or part of the technical solutions provided by the above embodiments can be realized by software programming, and the software program is stored in a readable storage medium, such as a hard disk, an optical disk or a floppy disk in a computer.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (10)

1. A multi-code type optical transmitter is characterized in that, said transmitter comprises: A pre-coding processing module, configured to perform differential coding on the data to be sent, generate coded data, and output two channels of coded data; a modulator, configured to receive an input optical signal and two channels of coded data output by the precoding processing module, modulate the two channels of coded data, and modulate the two channels of coded data onto the optical signal to generate And output carrier suppressed return-to-zero code optical signal or phase change return-to-zero code optical signal. 2. The multi-code type optical transmitter according to claim 1, wherein the precoding processing module comprises: A demultiplexer, configured to convert the data to be sent into two paths of data through serial-to-parallel conversion, and output the two paths of data respectively; The first precoder is configured to receive one path of data output by the demultiplexer, differentially encode the one path of data, generate one path of encoded data, and output the one path of encoded data; The second precoder is configured to receive another path of data output by the demultiplexer, differentially encode the other path of data, generate another path of encoded data, and output the other path of encoded data. 3. The multi-code type optical transmitter according to claim 1, wherein the precoding processing module comprises: a precoder, configured to differentially encode the data to be sent, generate encoded data, and output the encoded data; The demultiplexer is used to receive the encoded data output by the precoder, convert the encoded data into two channels through serial-to-parallel conversion, and output the two channels of encoded data respectively. 4. The multi-code type optical transmitter according to claim 1, wherein the precoding processing module further comprises: The amplifier is used to amplify the generated encoded data and output the amplified encoded data. 5. The multi-code type optical transmitter according to claim 1, wherein the modulator comprises: The optical signal input port is used to receive the optical signal and divide the optical signal into two paths; The first sub-modulator is configured to receive one path of optical signal from the optical signal input port and one path of coded data output by the precoding processing module, and modulate the one path of coded data to the Generate the first return-to-zero code signal on the above-mentioned one-way optical signal, and output the first-way return-to-zero code signal; An electrically adjustable delay line module, configured to receive another path of encoded data output by the pre-encoding processing module, and delay the other path of encoded data, so that the other path of encoded data and the one path of encoded data generate a preset The length of the delay, the encoded data after the output delay; The second sub-modulator is used to receive another optical signal from the optical signal input port and the time-delayed coded data output by the electrically adjustable delay line module, and convert the The time-delayed encoded data is modulated onto the other optical signal to generate a second return-to-zero code signal, and output the second return-to-zero code signal; A combining module, configured to receive the first return-to-zero code signal output by the first sub-modulator and the second return-to-zero code signal output by the second sub-modulator, and make the return-to-zero code signal output by the second sub-modulator The first return-to-zero signal and the second return-to-zero signal are combined to generate a carrier-suppressed return-to-zero optical signal or a phase-change return-to-zero optical signal. 6. A method for optical signal generation, characterized in that the method comprises: Perform differential encoding on the data to be sent to generate two channels of encoded data; The two channels of coded data are modulated, and the two channels of coded data are modulated onto an optical signal to generate a carrier suppression return-to-zero code optical signal or a phase change return-to-zero code optical signal. 7. The method for optical signal generation as claimed in claim 6, characterized in that, said data to be sent is differentially encoded, and the step of generating two-way encoded data comprises: converting the data to be sent into two channels of data through serial-to-parallel conversion; Differential encoding is performed on the two channels of data respectively to generate two channels of encoded data. 8. The method for optical signal generation as claimed in claim 6, characterized in that, said data to be sent is differentially encoded, and the step of generating two-way encoded data comprises: Perform differential encoding on the data to be sent to generate encoded data; The encoded data is converted into two channels through serial-to-parallel conversion to obtain two channels of encoded data. 9. The method for optical signal generation according to claim 6, characterized in that, after the step of generating two-way coded data, it also includes: Signal amplification is performed on the coded data to obtain coded data after signal amplification. 10. The method for generating an optical signal according to claim 6, wherein the step of modulating the two-way coded data and modulating the two-way coded data onto the optical signal comprises: receiving an optical signal and splitting the optical signal into two paths; Modulating one channel of coded data onto one channel of optical signals under the action of the first bias voltage to generate a first channel of return-to-zero code signals; Delaying another channel of encoded data, so that the other channel of encoded data and the first channel of encoded data generate a time delay of a preset length, and modulate the time-delayed encoded data to the other channel under the action of the second bias voltage On the optical signal, generate the second return-to-zero code signal; After combining the first return-to-zero code signal and the second return-to-zero code signal under the action of the third bias voltage, a carrier-suppressed return-to-zero code signal or a phase-changed return-to-zero code signal is generated.

Images