WO2022042415A1

WO2022042415A1 - Transmitted optical signal processing method and apparatus for optical signal transmission circuit,and device

Info

Publication number: WO2022042415A1
Application number: PCT/CN2021/113512
Authority: WO
Inventors: 郑克爽; 卢彦兆
Original assignee: 华为技术有限公司
Priority date: 2020-08-27
Filing date: 2021-08-19
Publication date: 2022-03-03
Also published as: CN114124230A

Abstract

The embodiments of the present application provide a transmitted optical signal processing method and apparatus for an optical signal transmission circuit, and a device, relating to the field of optical communication technology, and being able to implement real-time monitoring of various modulated optical signals. Said method comprises: dividing a transmitted optical signal outputted by an optical signal transmission circuit into a first optical signal and a second optical signal, wherein the transmitted optical signal comprises at least two modulated optical signals, and the modulated optical signals are generated by performing electro-optical modulation on a carrier optical signal according to a predetermined modulation format; sending the first optical signal to an optical signal reception circuit; acquiring a low frequency component of each modulated optical signal in the second optical signal; and adjusting a bias voltage of the modulated optical signal according to a predetermined step, and acquiring the change value of the power of the low frequency component over the predetermined step.

Description

Transmitting optical signal processing method, device and equipment of optical signal transmitting circuit

This application claims the priority of the Chinese patent application filed on August 27, 2020 with the State Intellectual Property Office of the People's Republic of China, the application number is 202010881238.5, and the application name is "transmitting optical signal processing method, device and equipment of optical signal transmitting circuit". The entire contents of this application are incorporated by reference.

technical field

The present application relates to the technical field of optical communication, and in particular, to a method, apparatus, and device for processing a transmitted optical signal of an optical signal transmitting circuit.

Background technique

The application of the network in our daily life is increasingly extensive, such as augmented reality (AR), virtual reality (VR), webcasting and 8K ultra-clear video, etc. The commercial single-wave 100G/200G rate cannot be To meet people's growing demand for Internet access, the single-wave rate will gradually increase to 400G/800G or even 1.2T in the future. Usually, increasing the signal baud rate or modulation format is an effective way to increase the single-wave rate. Since the range of signal baud rate improvement is limited by the bandwidth of electrical devices, it cannot support ultra-high-speed signal transmission alone. It is necessary to use 64 quadrature amplitude modulation in combination. (quadrature amplitude modulation, QAM) and higher-order modulation formats. However, the application of the high modulation format will further compress the Euclidean distance between the constellation points, so that the I (in-phase, in-phase) channel and the Q (quadrature, quadrature) channel in the modulated optical signal are slightly unbalanced due to power It may lead to serious degradation of system performance. Therefore, it is necessary to monitor the power of each modulated optical signal in real time and compensate for the power difference between them.

SUMMARY OF THE INVENTION

Embodiments of the present application provide a method, device, and device for processing an transmitted optical signal of an optical signal transmitting circuit, which can realize real-time monitoring of each modulated optical signal.

In a first aspect, a method for processing an transmitted optical signal of an optical signal transmitting circuit is provided. The transmission optical signal processing method of the optical signal transmission circuit is used in the transmission optical signal processing device of the optical signal transmission circuit. The method includes: dividing the transmitted optical signal output by the optical signal transmitting circuit into a first optical signal and a second optical signal, wherein the transmitted optical signal includes at least two modulated optical signals, wherein the modulated optical signal is a pair of optical signals according to a predetermined modulation format. The carrier optical signal is electro-optically modulated to generate; the first optical signal is sent to the optical signal receiving circuit; the low frequency component of each modulated optical signal in the second optical signal is acquired; the bias voltage of the modulated optical signal is adjusted according to a predetermined step size; Obtain the change value of the power of the low frequency component with a predetermined step size. In the above solution, the emitted optical signal processing device of the optical signal transmission circuit can divide the emitted optical signal output by the optical signal transmission circuit into the first optical signal and the second optical signal, wherein the emitted optical signal includes at least two modulated optical signals. The modulated optical signal is generated by electro-optically modulating the carrier optical signal according to a predetermined modulation format; sending the first optical signal to the optical signal receiving circuit; and then acquiring the low-frequency components of each modulated optical signal in the second optical signal; The bias voltage of the modulated optical signal is adjusted according to the predetermined step size, and the change value of the power of the low-frequency component with the predetermined step size is obtained, thus realizing the real-time monitoring of the modulated optical signals of the transmitted optical signals.

In a possible implementation manner, the method further includes: when it is determined that the difference between the change values corresponding to any two modulated optical signals is greater than or equal to the first threshold, adjusting the amplitude of the at least two modulated optical signals until the at least two modulated optical signals are modulated. The difference between the change values corresponding to any two modulated optical signals in the optical signal is smaller than the first threshold. The setting of the first threshold is mainly set according to the parameters of the modulator. In this embodiment, the power balance of the modulated optical signals of each channel is realized.

In a possible implementation manner, the method further includes: acquiring the slope of the power of the low-frequency component changing with the predetermined step size, where the slope is S=ΔP/δ, where δ is the predetermined step size; P is the power; ΔP is the change value of the power of the low-frequency component when the bias voltage changes by δ; when it is determined that the difference between the slopes corresponding to any two modulated optical signals is greater than or equal to the second threshold, adjust at least two modulated optical signals. amplitude, until the difference between the slopes corresponding to any two modulated optical signals among the at least two modulated optical signals is smaller than the second threshold. In this embodiment, the power balance of the modulated optical signals of each channel is realized. In addition, when the adjustment step size of the bias voltage is small, the change value of the power of the low frequency component is not obvious enough, and the predetermined step size δ is also a small value, so taking the ratio of ΔP/δ can amplify ΔP The difference between them improves the accuracy of power balance control.

In a possible implementation manner, the method further includes: adjusting the amplitudes of the at least two modulated optical signals, including: controlling the amplitude of any modulated optical signal to keep constant, and adjusting the amplitudes of other modulated optical signals. Specifically, the method further includes: adjusting the amplitude of the modulation signal of the modulated optical signal, so as to adjust the amplitude of the modulated optical signal.

In a possible implementation manner, the method further includes: adjusting the bias voltage to an initial value.

In a possible implementation manner, among the at least two modulated optical signals, any two modulated optical signals with the same polarization state have different phases; or any two modulated signals with the same phase have different polarization states.

In a second aspect, an emission optical signal processing device of an optical signal transmission circuit is provided, comprising: an optical splitter configured to divide the emission optical signal output by the optical signal transmission circuit into a first optical signal and a second optical signal, wherein The transmitted optical signal includes at least two modulated optical signals, wherein the modulated optical signal is generated by electro-optically modulating a carrier optical signal according to a predetermined modulation format; sending the first optical signal to an optical signal receiving circuit; a filter , which is used to obtain the low-frequency component of each modulated optical signal in the second optical signal; the processor is used to adjust the bias voltage of the modulated optical signal according to a predetermined step size; the processor, It is also used to obtain the change value of the power of the low-frequency component with the predetermined step size.

In a possible implementation manner, the processor is further configured to adjust at least two channels of the modulated optical signals when it is determined that the difference between the change values corresponding to any two channels of the modulated optical signals is greater than or equal to a first threshold The amplitude of the signal until the difference between the corresponding change values of any two modulated optical signals in the at least two modulated optical signals is smaller than the first threshold.

In a possible implementation manner, the processor is further configured to obtain a slope of the power of the low-frequency component changing with the predetermined step size, the slope S=ΔP/δ, where δ is the Predetermined step size, P is the power of the low-frequency component, ΔP is the change value of the power of the low-frequency component when the bias voltage changes by δ; the processor is further configured to determine when any two channels of the When the difference between the slopes corresponding to the modulated optical signals is greater than or equal to the second threshold, adjust the amplitude of any two modulated optical signals in the at least two modulated optical signals until the at least two modulated optical signals correspond to The difference of the slopes is smaller than the second threshold.

In a possible implementation manner, the processor is specifically configured to control the amplitude of any one of the modulated optical signals to remain constant, and to adjust the amplitudes of the other modulated optical signals.

In a possible implementation manner, the processor is specifically configured to adjust the amplitude of the modulated signal of the modulated optical signal, so as to adjust the amplitude of the modulated optical signal.

In a possible implementation manner, the processor is further configured to adjust the bias voltage to an initial value.

In a possible implementation manner, among the at least two modulated optical signals, any two modulated optical signals with the same polarization state have different phases; or any two modulated optical signals with the same phase have the same polarization state.

In a third aspect, an optical signal transmitter is provided, comprising: an optical signal transmitting circuit and the above-mentioned transmitting optical signal processing device of the optical signal transmitting circuit.

In a fourth aspect, a communication device is provided, comprising the above-mentioned optical signal transmitter and a signal source, the signal source is configured to output an electrical signal to the optical signal transmitter, and an optical signal transmitting circuit in the optical signal transmitter for converting the electrical signal into the emitted light signal.

Wherein, for the technical effect brought by any possible implementation manner of the second aspect to the fourth aspect, reference may be made to the technical effect brought by the different implementation manners in the above-mentioned first aspect, which will not be repeated here.

Description of drawings

FIG. 1 is a schematic structural diagram of an optical module according to an embodiment of the present application;

FIG. 2 is a schematic structural diagram of an optical signal transmitting circuit according to an embodiment of the present application;

3 is a schematic structural diagram of an optical signal transmitting circuit according to another embodiment of the present application;

4 is a schematic structural diagram of a modulator according to an embodiment of the present application;

FIG. 5 is a schematic structural diagram of a modulator according to another embodiment of the present application;

FIG. 6 is a schematic structural diagram of a modulator according to still another embodiment of the present application;

FIG. 7 is a schematic diagram of a modulation principle of a carrier optical signal according to an embodiment of the present application;

FIG. 8 provides a schematic structural diagram of an apparatus for processing an transmitted optical signal of an optical signal transmitting circuit according to an embodiment of the present application;

FIG. 9 provides a schematic diagram of a filtering principle according to an embodiment of the present application;

FIG. 10 provides a graph of the voltage difference δ between the bias voltage and the quad point and the power variation ΔP of the signal for an embodiment of the application;

FIG. 11 provides a schematic flowchart of a method for processing an transmitted optical signal of an optical signal transmitting circuit according to an embodiment of the present application;

FIG. 12 provides a schematic flowchart of a method for processing an transmitted optical signal of an optical signal transmitting circuit according to another embodiment of the present application;

FIG. 13 provides a schematic flowchart of a method for processing an transmitted optical signal of an optical signal transmitting circuit according to yet another embodiment of the present application.

detailed description

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.

The embodiments of the present application are applied to an optical signal transmitter. The optical signal transmitter includes an optical signal transmitting circuit. The function of the optical signal transmitting circuit is to convert an electrical signal into an optical signal, and input the optical fiber for transmission to the optical signal receiving circuit. In addition, the embodiments of the present application can also be applied to an optical module, and the function of the optical module is photoelectric conversion. The optical module is also called an optical transmission module. Referring to FIG. 1 , the optical module includes an optical signal transmitting circuit 11 and an optical signal receiving circuit 12 . The function of the optical signal transmitting circuit 11 is to convert the electrical signal into an optical signal, and input the optical signal 13 for transmission. The function of the optical signal receiving circuit 12 is to receive the optical signal transmitted from the optical fiber 13 and convert it to an electrical signal. The optical signal transmitting circuit 11 and the optical signal receiving circuit 12 in FIG. 1 can multiplex the optical fiber 13 . Of course, the optical signals of the optical signal transmitting circuit 11 and the optical signal receiving circuit 12 can also be transmitted in two optical fibers respectively. Usually, the optical module at the transmitting end converts the electrical signal into an optical signal, and after transmission through the optical fiber, the optical module at the receiving end converts the optical signal into an electrical signal.

Among them, optical signal transmitters or optical modules are mainly used in Ethernet, fiber to the home (FTTH), optical transport network (OTN), network storage, data centers and other fields. Based on the above application fields, optical signal transmitters or optical modules are mainly used in the above fields such as: optical line terminal (OLT), optical network unit (ONU), switch, optical fiber router, video Optical transceivers, optical transceivers, optical fiber network cards and other equipment. The communication device may also include a signal source for generating electrical signals and inputting the electrical signals to an optical signal transmitter (or optical module). Optical signal transmitters transmit through optical fibers by converting electrical signals into optical signals. Among them, optical signal transmitters and optical modules support different rate classifications, such as: 1G~10G low rate, 25G, 40G, 50G, 100G, 200G/400G, etc.

In order to convert electrical signals into optical signals, an example of this application provides an optical signal transmitting circuit, as shown in FIG. 2 and FIG. 3 , including: a light source 21 , a driver 23 , and a modulator 24 . The light source 21 is connected to the optical input port of the modulator 24, the signal source 22 is connected to the electrical signal input port of the modulator 24 through the driver 23, and the optical output port of the modulator 24 is connected to the output terminal out of the optical signal transmitting circuit. Wherein, the light source 21 can be a laser (laser diode, LD, also known as a laser diode) for generating a carrier optical signal, the signal source 22 is used for generating a transmitting electrical signal; the driver 23 is used for amplifying the transmitting electrical signal to generate a modulation signal; modulation The device 24 is used to modulate the modulated signal onto the carrier optical signal to generate the modulated optical signal.

In addition, in order to realize multi-channel modulated optical signals, that is, multiplexing multiple modulated optical signals into the same transmission fiber, the embodiments of the present application may form modulated optical signals in different modulation modes. At this time, the optical signal transmitting circuit may include a plurality of modulators 24 (such as modulators 24-1, 24-2 in FIG. 2, and modulators 24-1, 24-2, 24-3, 24-4 in FIG. 3) , where each modulator 24 is used for modulation of one modulated optical signal; the signal source 22 can respectively generate a transmit electrical signal corresponding to each modulator 24 , and each modulator 24 supports one modulated optical signal. For example: any two modulated optical signals with the same polarization state have different phases; any two modulated optical signals with the same phase have different polarization states. Referring to FIG. 3 , the optical signal transmitting circuit may further include a polarizing beam splitter (PBS) 26 located between the light source 21 and the modulator 24 , and a polarization combiner (polarizing beam splitter) disposed at the output end of the modulator 24 beam combiner, PBC) 27; wherein, the PBS can split the carrier optical signal into optical signals with different polarization states, and input them to the corresponding modulator 24. The PBC 27 is used to combine the modulated optical signals output by different modulators 24 into the same transmission fiber. In order to realize that different modulated optical signals have different phases, as shown in FIG. 2 , the optical output port of the modulator 24-2 is connected to a phase shifter 25 for phase shifting the modulated optical signal output by the modulator 24-2.

Taking quadrature amplitude modulation (QAM) as an example, as shown in FIG. 2, the optical signal transmitting circuit may include at least two modulators 24, wherein the optical output port of one modulator 24-1 is directly connected to the transmitting circuit. The output terminal is out, and the optical output port of the other modulator 24-2 passes through the phase shifter 25 (wherein the phase shifter 25 is a π/2 phase shifter, which is used to perform π/2 on the optical signal output by the modulator 24-2). Phase shift) is connected to the output port out of the transmitting circuit, so that the carrier optical signal output by the light source 21 passes through the modulated optical signal XI formed after the branch of the modulator 24-1, and the carrier optical signal output by the light source 21 passes through the modulator 24-2. The modulated optical signal XQ formed after the branch has a phase difference of π/2, thereby realizing QAM modulation. Specifically, FIG. 2 takes the realization of two-channel modulated optical signals (XI, XQ) as an example, where XI and XQ are different in phase by 90°; wherein, the carrier optical signals generated by the light source 21 are respectively output to the modulators 24- 1 and a modulator 24-2, the signal source 22 is used to generate two channels of transmitting electrical signals XI-Amp and XQ-AMP; the driver 23 is used to amplify the transmitting electrical signals XI-Amp and XQ-AMP respectively to generate a modulated signal XI- Urf(t), XQ-Urf(t); wherein the driver 23 independently amplifies the various transmission electrical signals XI-Amp and XQ-AMP in this application, that is, the various transmission electrical signals can be amplified with different gain multiples, In the embodiments of the present application, in order to monitor and equalize the modulated optical signals of each channel, the driver amplifies the transmit electrical signals of each channel with a constant gain multiple, and amplifies the transmit electrical signals of each channel with the same gain multiple. The modulator 24-1 modulates the modulated signal XI-Urf(t) to the carrier optical signal to generate the modulated optical signal XI; the modulator 24-1 modulates the modulated signal XQ-Urf(t) to the on-wave optical signal and passes π/2 The phase shifter 25 performs a phase shift of 90° to generate the modulated optical signal XQ.

In addition, as shown in FIG. 3 , the embodiment of the present application can also realize four channels of modulated optical signals (XI, XQ, YI, YQ), wherein the optical signal transmitting circuit further includes: PBS26 and PBC27, wherein PBS26 sets Between the light source 21 and the modulator 24, the carrier optical signal can be split into two carrier optical signals X and Y with different polarization states. For example, the polarization directions of the carrier optical signals X and Y are perpendicular to each other. Then, the carrier optical signal X is respectively transmitted to the corresponding modulators 24-1 and 24-2 for modulation to form modulated optical signals XI and XQ; the carrier optical signal Y is respectively transmitted to the corresponding modulators 24-3 and 24-2. 24-4 is modulated to form modulated optical signals YI, YQ. Finally, the polarization combiner 27 is combined to the output end out of the optical signal transmitting circuit.

The above embodiments describe the modulation methods of the two-channel and four-channel modulated optical signals in detail. When more channels of modulated optical signals need to be realized, the carrier optical signal of the light source 21 can be split into light with more polarization states through the PBS. Signal.

For the modulator 24, a Mach-Zehnder (MZ) modulator may be used, and the MZ modulator may be an MZ modulator such as silicon photonics, lithium niobate LiNbO ₃ , indium phosphide INP, or the like. As shown in Figure 4, Figure 5, and Figure 6, the MZ modulator may be an interferometer formed by using waveguides A and B formed by diffusion of titanium on the surface of LiNbO ₃ crystal in parallel. Among them, the carrier optical signal Ein(t) is input into the waveguides A and B through the input port C, and two polarized light waves with the same frequency but different phases are formed in the waveguides A and B. Interfere to obtain a modulated optical signal Eout(t), wherein applying a voltage (ie, modulating signal) Urf(t) to A and/or B can introduce a change in phase that can be converted into a change in amplitude. The modulation signal Urf(t) may be applied to either or both of the waveguides A or B as shown in FIG. 4 , FIG. 5 , and FIG. 6 . In addition, the modulator needs to perform signal modulation at a stable DC bias operating point (quad point), so Figures 4, 5, and 6 also show the DC bias voltage Udc(t) applied by A and/or B ), whose function is to adjust the DC bias operating point of the modulator. Among them, the Urf(t) input on the A and B waveguides in Fig. 4 is in the differential form, so that the modulator works in the push-pull mode to realize the intensity modulation of the signals input to the waveguides A and B. As shown in Figure 7, the modulation principle of the carrier optical signal is that the carrier optical signal changes the waveform (amplitude and phase) under the action of the input electrical signal Es (ie Urf(t)+Udc(t)) to generate modulation Optical signal Os.

Based on the above-mentioned optical signal transmitting circuit, as shown in FIG. 8 , a schematic structural diagram of a transmitting optical signal processing apparatus of the optical signal transmitting circuit is provided, including: an optical splitter 81 , a filter 82 and a processor 83 .

The optical splitter 81 is used to divide the transmitted optical signal output by the optical signal transmitting circuit into a first optical signal and a second optical signal, wherein the transmitted optical signal includes at least two modulated optical signals, wherein the modulated optical signal is according to The predetermined modulation format performs electro-optical modulation on the carrier optical signal to generate; the first optical signal is sent to the optical signal receiver. The predetermined modulation format in the embodiment of the present application may be any of the following modulation formats: quadrature phase shift keying (QPSK), 8QAM (quadrature amplitude modulation, quadrature amplitude modulation), 16QAM , 32QAM, 64QAM, 128QAM, 256QAM.

The filter 82 is used to obtain the low-frequency components of each modulated optical signal in the second optical signal. The filter 82 is a low-pass filter, that is, the filter 82 has the characteristics of passing low frequencies and blocking high frequencies, so that the low frequency components in the modulated optical signal are passed through the filter 82 through the filter, and the high frequency AC components are filtered out. Among them, the frequency range of the modulated optical signal is usually 0 to 80GHZ, which will be further increased with the upper limit of 80GHZ. The low-frequency component provided by the embodiments of the present application refers to the frequency range of the relatively modulated optical signal, and the low-frequency component is the low-frequency part of the communication optical signal, for example, 0 to 1 GHz. In the simulation process of the following example, the frequency range of the low-frequency component is 0 To 100KHZ as an example to illustrate.

The processor 83 is configured to adjust the bias voltage of the modulated optical signal according to the predetermined step size; the processor 83 is further configured to obtain the change value of the power of the low frequency component with the predetermined step size.

Among them, the bias voltage is the above-mentioned Udc(t), and the bias voltage Udc(t) is usually a DC fixed value Udc, and its value mainly depends on the curve of the modulating signal (that is, the transmission signal output by the above signal source). amplitude). The processor 83 may change the initial value Udc of the bias voltage according to the predetermined step size δu, for example, the bias voltage may be gradually decreased according to the predetermined step size δu, or the bias voltage may be gradually increased according to the predetermined step size; the processor 83 may A photodiode is used to monitor the power of the low-frequency components of the modulated optical signal. For example, after the bias voltage of the modulated optical signal XI is reduced by a predetermined step size δu, the bias voltage is Udc-δu; the bias voltage can be detected by the photodiode are the power P1 _XI of the low-frequency component of the modulated optical signal XI when Udc is Udc, and the power P2 _XI of the low-frequency component of the modulated optical signal XI when the bias voltage is Udc- _δu .

Specifically, after the bias voltage of any modulated optical signal is adjusted, the specific description of obtaining the change value of the power of the low-frequency component of the modulated optical signal with the predetermined step size is as follows:

Taking the modulated optical signal XI as an example for illustration, the power P _XI of the low-frequency component of the modulated optical signal XI can be expressed as:

P _XI =(XI_Amp*GXI*AttXI) ² *F_f+DC(Udc) (Formula 1).

XI_Amp: is the amplitude of the transmitting electrical signal XI-Amp. Taking the optical signal transmitting circuit shown in Figure 3 as an example, the initial values of the four transmitting electrical signals are set to be the same, that is, (XI-Amp)=(XQ-Amp)= (YI-Amp)=(YQ-Amp); GXI: is the gain of the transmitted electrical signal XI-Amp, in the embodiment of this application, the four-way gain is set to be the same; AttXI: is the insertion loss of the modulated optical signal XI, for For the modulated optical signal XI, it is a fixed value. Since each optical signal passes through different devices, the insertion loss between the four channels is inconsistent; the square of the product of the above three items XI_Amp, GXI and AttXI is the total of the modulated optical signal XI. power. F_f is the filter power conversion coefficient, which is a constant, where F is the bandwidth of the modulated optical signal, and f is the bandwidth of the low-frequency component output by the filter 82 . DC(Udc): It is a function of the DC bias voltage Udc, depending on the curve of the modulating signal, and the magnitude of the bias voltage can be changed by adjusting Udc. The calculation method of the power P XQ of the low frequency component of the modulated optical signal _XQ , the power P YI of the low frequency component of _YI and the power P _YQ of the low frequency component of YQ is similar to that of P _XI .

In combination with the above description, the total power P of the modulated optical signal is related to the amplitude Amp of the transmitted electrical signal, the gain multiple G of the driver, and the insertion loss Att. As shown in FIG. 9, after low-pass filtering by the filter 82, the power of the low-frequency component of the modulated optical signal obtained is P', P/P'=F/f, F is the bandwidth of the modulated optical signal, and f is the filtered optical signal. The bandwidth of the low-frequency component of the optical signal. When the bias voltage Udc of the modulator changes slightly around the quad point, the electro-optical conversion curve (or called the modulation curve) can be regarded as linear. At this time, changing the bias voltage Udc will only change the DC in the modulated optical signal. power, but has no effect on non-DC components. The simulation results are shown in Figure 10. In Figure 10, the horizontal axis x represents the voltage difference δ between the bias voltage and the quad point, and the vertical axis y represents the signal when the bias voltage is changed. The power change ΔP. It can be seen from Figure 10 that when the bias voltage Udc is changed, the total signal power P and the total power P' of the low-frequency component have exactly the same change value, that is to say, a small change in Udc around the quad point will only change the DC component in the modulated optical signal. , and has little effect on the non-DC components.

When the bias voltages of the four channels are all Udc, the total power of the low-frequency components of the four channels of modulated optical signals is P'=P _XI (Udc)+P _XQ (Udc)+P _YI (Udc)+P _YQ ( Udc); when the bias voltage of the modulated optical signal XI is set to Udc+δ, the bias voltages of the other three modulated optical signals remain unchanged, and the total power of the low-frequency components of the four modulated optical signals is P _XI ( Udc+δ)+P _XQ (Udc)+P _YI (Udc)+P _YQ (Udc), the two are subtracted to obtain the change value of the power of the low-frequency component of the modulated optical signal XI with the predetermined step size ΔP _XI =P _XI (Udc+δ)-P _XI (Udc), in the same way, ΔP _XQ , ΔP _YI , ΔP _YQ can be obtained. In this way, through one photodiode, the four modulated optical signals are respectively detected once, and the change value of the power of the low-frequency components of each modulated optical signal with the predetermined step size can be detected.

Usually, the bias voltage is a fixed value, however, the DC bias point of the modulator will "drift" with the change of the ambient temperature, resulting in the deterioration of the transmission system performance. Therefore, the bias voltage Udc of the modulator is usually Add a low-frequency perturbation signal (that is, dither) to monitor and adjust the DC bias operating point (abbreviated as bias point) of the modulator, so that the modulator always works in the correct state, that is, the quad point, as shown in the figure 7 shows the DC bias operating point. Assuming that the bias voltage Udc of the modulator is 3.5V, the dither amplitude is a sine or square wave signal with a dither amplitude of 0.1V and a frequency of 1KHz, then Udc will swing around the quad point with a frequency of 1KHz. In the embodiment of the present application, the perturbation signal can be multiplexed, and the bias voltage can be adjusted by adjusting the frequency and amplitude of the dither signal to form a predetermined step size. Alternatively, a separate circuit may be added to generate the predetermined step size to adjust the bias voltage. It should be noted that, when implementing the solutions provided by the embodiments of the present application, the existing perturbation signal dither needs to be suspended.

In the embodiments of the present application, since the optical splitter in the transmitted optical signal processing device of the optical signal transmitting circuit can divide the transmitted optical signal output by the optical signal transmitting circuit into the first optical signal and the second optical signal, wherein the optical signal is transmitted The optical signal includes at least two modulated optical signals, wherein the modulated optical signal is generated by electro-optically modulating the carrier optical signal according to a predetermined modulation format; the first optical signal is sent to the optical signal receiving circuit; the filter can obtain the second optical signal Each channel modulates the low-frequency components of the optical signal; the processor can adjust the bias voltage of the modulated optical signal according to a predetermined step, and obtain the change value of the power of the low-frequency component with the predetermined step. Thus, real-time monitoring of the modulated optical signals of each channel of the transmitted optical signals is realized.

Since the insertion loss of each modulated optical signal is not consistent, the ΔP _XI , ΔP _XQ , ΔP _YI , and ΔP _YQ calculated in combination with Formula 1 are not equal. Reflected on the modulated optical signal, the power of the modulated optical signal is unbalanced due to inconsistent insertion loss. As shown in FIG. 8, in order to achieve the power balance of the modulated optical signals of each channel: the processor 83 is used to determine any two channels. When the difference between the variation values corresponding to the modulated optical signals is greater than or equal to the first threshold, the amplitudes of the at least two modulated optical signals are adjusted until the difference between the variation values corresponding to any two modulated optical signals in the at least two modulated optical signals is equal to or equal to the first threshold. less than the first threshold. The setting of the first threshold is mainly set according to the parameters of the modulator. Specifically, the processor 83 is specifically configured to control the amplitude of any modulated optical signal to keep constant, and to adjust the amplitudes of other modulated optical signals. The processor 83 is specifically configured to adjust the amplitude of the modulated signal of the modulated optical signal, so as to adjust the amplitude of the modulated optical signal. For example, keep the amplitude of the modulated optical signal XI constant, that is, without adjusting the amplitude of the modulated signal of the modulated optical signal XI, adjust the amplitudes of the modulated signals of the modulated optical signals XQ, YI, YQ in turn, until ΔP _XI , ΔP _XQ , Δ The difference between P _YI and ΔP _YQ is smaller than the first threshold (for example, ΔP _XI , ΔP _XQ , ΔP _YI , and ΔP _YQ are all equal), thereby achieving power balance of the modulated optical signals. The modulation signal is the signal amplified by the driver of the transmitting electrical signal sent by the signal source, so the processor can adjust the amplitude of the modulating optical signal by adjusting the amplitude of the transmitting electrical signal through the signal source.

In addition, when the adjustment step size of the bias voltage is small, the change value of the power of the low-frequency component is not obvious enough. In order to improve the accuracy of the power balance control, in the embodiment of the present application, the processor 83 is also used to obtain the low-frequency component. The slope of the power changing with the predetermined step size, the slope S=ΔP/δ, where δ is the predetermined step size, P is the power of the low-frequency component, and ΔP is the power of the low-frequency component when the bias voltage changes by δ. change value.

Combining the above formula 1, the formula 1 can be converted into: P _XI =S(XI_Amp,AttXI)+DC(Udc) (formula 2).

That is, PXI can be regarded as a linear function of Udc, and S( _{XI_Amp} , AttXI) is a function of insertion loss and the amplitude of the transmitted electrical signal XI-Amp. For the modulated optical signal XI, S(XI_Amp, AttXI)=S _XI is a constant, and S _XI can be changed by adjusting the amplitude of the transmitted electrical signal XI-Amp. Since the ΔP difference between the four modulated optical signals may be small, the power variation of the low-frequency components is not obvious enough, which will affect the accuracy of the power equalization control. The predetermined step size δ is also a small value, so taking the ratio of the two can amplify the difference between ΔP, that is, ΔP/δ. The processor 83 is configured to adjust the amplitude of at least two modulated optical signals until the slope corresponding to at least two modulated optical signals when the difference between the slopes corresponding to any two modulated optical signals is determined to be greater than or equal to the second threshold The difference is smaller than the second threshold. In this way, since δ is sufficiently small, the slope S=ΔP/δ can be enlarged. The processor 83 is specifically configured to control the amplitude of any modulated optical signal to keep constant, and to adjust the amplitudes of other modulated optical signals. The processor 83 is specifically configured to adjust the modulation voltage of the modulated optical signal to adjust the amplitude of the modulated optical signal. For example, keep the amplitude of the modulated optical signal XI constant, that is, without adjusting the amplitude of the modulated signal of the modulated optical signal XI, adjust the amplitudes of the modulated signals of the modulated optical signals XQ, YI, YQ in turn, until S _XI , S _XQ , S _YI , The difference between each pair of S _YQ is smaller than the second threshold (for example, S _XI , S _XQ , S _YI , and S _YQ are all equal).

Based on the above-mentioned optical signal transmission circuit, as shown in FIG. 11 , an embodiment of the present application provides a method for processing an transmitted optical signal of an optical signal transmission circuit, including the following steps:

101. Divide the transmitted optical signal output by the optical signal transmitting circuit into a first optical signal and a second optical signal, wherein the transmitted optical signal includes at least two modulated optical signals, wherein the modulated optical signal is a carrier optical signal according to a predetermined modulation format. The signal is generated by electro-optic modulation.

102. Send the first optical signal to the optical signal receiving circuit.

103. Acquire low-frequency components of each modulated optical signal in the second optical signal.

104. Adjust the bias voltage of the modulated optical signal according to a predetermined step size.

105. Acquire a change value of the power of the low-frequency component with a predetermined step size.

In an embodiment, referring to FIG. 12 , different from the solution corresponding to FIG. 11 is that the method for processing the transmitted optical signal of the optical signal transmitting circuit provided in this embodiment further includes power compensation for the modulated optical signal, Specifically include the following steps:

201. Divide the transmitted optical signal output by the optical signal transmitting circuit into a first optical signal and a second optical signal.

The transmitted optical signal includes at least two modulated optical signals, wherein the modulated optical signal is generated by electro-optically modulating a carrier optical signal according to a predetermined modulation format.

202. Send the first optical signal to the optical signal receiving circuit.

203. Acquire low-frequency components of each modulated optical signal in the second optical signal.

204. Adjust the bias voltage of the modulated optical signal according to a predetermined step size.

205. Acquire a change value of the power of the low-frequency component with a predetermined step size.

206. When it is determined that the difference between the change values corresponding to any two modulated optical signals is greater than or equal to the first threshold, adjust the amplitude of the at least two modulated optical signals until any two modulated optical signals in the at least two modulated optical signals The differences of the corresponding change values are all smaller than the first threshold.

Wherein, step 206 specifically includes controlling the amplitude of any modulated optical signal to keep constant, and adjusting the amplitudes of other modulated optical signals. In addition, the amplitude of the modulated optical signal is adjusted by adjusting the amplitude of the modulated signal of the modulated optical signal.

207. Adjust the bias voltage to an initial value.

For example, the bias voltage is adjusted to Quad, or when the dither signal is multiplexed to adjust the bias voltage, the dither signal is switched back to monitor and adjust the DC bias operating point of the modulator.

In this way, after passing through steps 201-206, the equalization control of the modulated optical signal is realized, and then the bias voltage is restored to the initial value, that is, the DC bias operating point of the modulator, and the next monitoring and power equalization are started.

In an embodiment, referring to FIG. 13 , different from the solution corresponding to FIG. 11 is that the method for processing the transmitted optical signal of the optical signal transmitting circuit provided in this embodiment further includes power compensation for the modulated optical signal, Specifically include the following steps:

301. Divide the transmitted optical signal output by the optical signal transmitting circuit into a first optical signal and a second optical signal, wherein the transmitted optical signal includes at least two modulated optical signals, wherein the modulated optical signal is a carrier optical signal according to a predetermined modulation format. The signal is generated by electro-optic modulation.

302. Send the first optical signal to an optical signal receiving circuit.

303. Acquire low-frequency components of each modulated optical signal in the second optical signal.

304. Adjust the bias voltage of the modulated optical signal according to a predetermined step size.

305. Acquire a change value of the power of the low-frequency component with a predetermined step size.

306. Obtain the slope of the power of the low-frequency component changing with the predetermined step size.

Slope S=δP/δVb, where δVb is the predetermined step size, Vb is the bias voltage, P is the power of the low-frequency component, and δP is the power of the low-frequency component when the bias voltage changes by δVb. The change value of power;

307. When it is determined that the difference between the slopes corresponding to the at least two modulated optical signals is greater than or equal to the second threshold, adjust the amplitude of the at least two modulated optical signals until any two optical signals in the at least two modulated optical signals The differences of the corresponding slopes are all smaller than the second threshold.

Wherein, step 307 specifically includes controlling the amplitude of any modulated optical signal to keep constant, and adjusting the amplitudes of other modulated optical signals. In addition, the amplitude of the modulated optical signal is adjusted by adjusting the amplitude of the modulated signal of the modulated optical signal.

308. Adjust the bias voltage to an initial value.

In this way, after passing through steps 301-307, the equalization control of the modulated optical signal is realized, and then the bias voltage is restored to the initial value, that is, the DC bias operating point of the modulator, and the next monitoring and power equalization are started.

Among them, since the transmission optical signal processing device of the optical signal transmission circuit shown in FIG. 8 is used to implement the transmission optical signal processing method of the optical signal transmission circuit provided in FIG. 11 to FIG. For the specific description of each step of the method for processing the transmitted optical signal of the optical signal transmitting circuit, reference may be made to the description of the functions of each unit or module in the above-mentioned optical signal transmitting circuit for processing the transmitted optical signal. The corresponding description is given in the transmission light signal processing device of the signal transmission circuit.

Although the application has been described in conjunction with specific features and embodiments thereof, it will be apparent that various modifications and combinations can be made therein without departing from the spirit and scope of the application. Accordingly, this specification and drawings are merely exemplary illustrations of the application as defined by the appended claims, and are deemed to cover any and all modifications, variations, combinations or equivalents within the scope of this application. Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

A method for processing an transmitted optical signal of an optical signal transmitting circuit, comprising:

The transmitted optical signal output by the optical signal transmitting circuit is divided into a first optical signal and a second optical signal, wherein the transmitted optical signal includes at least two modulated optical signals, wherein the modulated optical signal is paired according to a predetermined modulation format. The carrier optical signal is generated by electro-optic modulation;

sending the first optical signal to the optical signal receiving circuit;

acquiring low-frequency components of each modulated optical signal in the second optical signal;

Adjust the bias voltage of the modulated optical signal according to a predetermined step size;

A change value of the power of the low-frequency component with the predetermined step size is obtained.
The method for processing the transmitted optical signal of an optical signal transmitting circuit according to claim 1, further comprising: when it is determined that the difference between the change values corresponding to any two of the modulated optical signals is greater than or equal to a first threshold value, The amplitudes of the at least two modulated optical signals are adjusted until the difference between the change values corresponding to any two modulated optical signals in the at least two modulated optical signals is smaller than the first threshold.
The method for processing the transmitted optical signal of an optical signal transmitting circuit according to claim 1, further comprising: acquiring a slope of the power of the low-frequency component changing with the predetermined step, the slope S=ΔP/ δ, where δ is the predetermined step size; P is the power of the low-frequency component; ΔP is the change value of the power of the low-frequency component when the bias voltage changes by δ;

When it is determined that the difference between the slopes corresponding to any two channels of the modulated optical signals is greater than or equal to the second threshold, adjust the amplitudes of the at least two channels of the modulated optical signals until any two channels of the at least two channels of the modulated optical signals are all The difference between the slopes corresponding to the modulated optical signal is smaller than the second threshold.
The method for processing the transmitted optical signal of an optical signal transmitting circuit according to claim 2 or 3, wherein the adjusting the amplitude of the at least two modulated optical signals comprises:

The amplitude of any one of the modulated optical signals is controlled to remain constant, and the amplitudes of the other modulated optical signals are adjusted.
The method for processing the transmitted optical signal of an optical signal transmitting circuit according to claim 2 or 3, further comprising: adjusting the amplitude of the modulated signal of the modulated optical signal to adjust the amplitude of the modulated optical signal.
The method for processing the transmitted optical signal of an optical signal transmitting circuit according to claim 2 or 3, further comprising: adjusting the bias voltage to an initial value.
The method for processing the transmitted optical signal of an optical signal transmitting circuit according to claim 1, wherein, among the at least two modulated optical signals, any two modulated optical signals with the same polarization state have different phases; or any two modulated optical signals have different phases; Modulated signals with the same phase have different polarization states.
A transmission optical signal processing device of an optical signal transmission circuit, characterized in that it comprises:

an optical splitter for dividing the transmitted optical signal output by the optical signal transmitting circuit into a first optical signal and a second optical signal, wherein the transmitted optical signal includes at least two modulated optical signals, wherein the modulated optical signal is Perform electro-optical modulation on the carrier optical signal according to a predetermined modulation format; send the first optical signal to the optical signal receiving circuit;

a filter, configured to obtain the low-frequency component of each modulated optical signal in the second optical signal;

a processor, configured to adjust the bias voltage of the modulated optical signal according to a predetermined step size;

The processor is further configured to obtain a change value of the power of the low-frequency component with the predetermined step size.
The transmitted optical signal processing device of the optical signal transmitting circuit according to claim 8, wherein the processor is further configured to determine that the difference between the corresponding change values of any two modulated optical signals is greater than or equal to When the first threshold is set, the amplitudes of the at least two modulated optical signals are adjusted until the difference between the corresponding change values of any two modulated optical signals in the at least two modulated optical signals is smaller than the first threshold.
The transmitted optical signal processing device of an optical signal transmitting circuit according to claim 8, wherein the processor is further configured to obtain a slope of the power of the low-frequency component changing with the predetermined step size, the slope S=ΔP/δ, where δ is the predetermined step size, P is the power of the low-frequency component, and ΔP is the change value of the power of the low-frequency component when the bias voltage changes by δ;

The processor is further configured to adjust any two modulated optical signals of the at least two modulated optical signals when the difference between the slopes corresponding to any two modulated optical signals is determined to be greater than or equal to a second threshold until the difference between the slopes corresponding to the at least two modulated optical signals is smaller than the second threshold.
The transmitted optical signal processing device of an optical signal transmitting circuit according to claim 9 or 10, wherein the processor is specifically configured to control the amplitude of any one of the modulated optical signals to keep constant, and adjust the other modulated optical signals the amplitude of the signal.
The transmitted optical signal processing device of an optical signal transmitting circuit according to claim 9 or 10, wherein the processor is specifically configured to adjust the amplitude of the modulated signal of the modulated optical signal, so as to adjust the modulated optical signal Amplitude.
The transmitted optical signal processing device of an optical signal transmitting circuit according to claim 9 or 10, wherein the processor is further configured to adjust the bias voltage to an initial value.
The transmitted optical signal processing device of an optical signal transmitting circuit according to claim 8, wherein, among the at least two modulated optical signals, any two modulated optical signals with the same polarization state have different phases; or any two modulated optical signals have different phases; Modulated signals with the same phase have the same polarization state.
An optical signal transmitter, characterized in that it comprises: an optical signal transmitting circuit and the transmitting optical signal processing device of the optical signal transmitting circuit according to any one of claims 8-14.
A communication device, characterized in that it comprises the optical signal transmitter according to claim 15 and a signal source, wherein the signal source is used for outputting an electrical signal to the optical signal transmitter, wherein the optical signal transmitter The optical signal transmitting circuit is used for converting the electrical signal into the transmitting optical signal.