A method and device for controlling bias operating point of a modulator

Abstract

The present invention relates to the technical field of optical modulators, and provides a method and device for controlling the bias operating point of a modulator. The method comprises the following steps: after selecting a phase modulation electrode I to apply a disturbance signal, using a pair of constructed orthogonal bases, performing an integral operation on an optical signal outputted by a modulator, obtaining a first result corresponding to the phase modulation electrode I currently applying the disturbance signal in the integral operation result; performing linear fitting on the first result and the bias control point to obtain a first fitting degree, and if the first fitting degree does not belong to a preset fitting interval, adjusting the amplitude of the disturbance signal until the recalculated first fitting degree belongs to the preset fitting interval, thereby obtaining an ideal disturbance signal amplitude for applying the phase modulation electrode I. The present invention reduces the locking effect caused by the amplitude of the disturbance signal and improves the control accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of optical modulators, and in particular to a method and device for controlling a bias operating point of a modulator. Background Art

[0002] With the rapid development of data services, there are requirements for higher speed, longer distance and larger capacity of optical fiber communication. Coherent communication has emerged as the times require, and a large number of coherent communication researches have sprung up. Among them, optical modulator is an important device in coherent communication. When the optical modulator is used, it is necessary to load the optical modulator with a suitable DC bias voltage to ensure that it works at the appropriate working point, optimize the modulation signal and improve the system performance.

[0003] At present, the feedback control method of low-frequency disturbance signal is often used in engineering. The method mainly applies a low-frequency and small-amplitude sinusoidal signal to the modulation arm of the optical modulator, detects the information of the frequency component related to the output optical power, and obtains the feedback information of the DC bias voltage. However, this method inevitably introduces a perturbation signal. The size of the perturbation signal will directly affect the jitter degree of the signal. A large perturbation signal will make the modulated signal unable to be parsed, resulting in uncorrectable code errors, affecting the communication status of the link.

[0004] In view of this, overcoming the defects of the prior art is an urgent problem to be solved in the field of this technology. Summary of the invention

[0005] The technical problem to be solved by the present invention is that the prior art inevitably introduces a perturbation signal. The size of the perturbation signal will directly affect the degree of signal jitter. A larger perturbation signal will make the modulated signal unable to be parsed, resulting in uncorrectable code errors, affecting the communication status of the link.

[0006] The present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for controlling a bias operating point of a modulator. When the phase modulation electrode of the modulator includes a phase modulation electrode I located on a first waveguide and a phase modulation electrode Q located on a second waveguide, the control method includes:

[0008] Setting an initial bias control point for the phase modulation electrode I and the phase modulation electrode Q, and selecting the phase modulation electrode I and the phase modulation electrode Q one by one as the phase modulation electrode to which the disturbance signal is applied; wherein the initial bias control point and the disturbance signal constitute the bias control point of the corresponding phase modulation electrode;

[0009] After selecting a phase modulation electrode I to apply a disturbance signal, using a pair of constructed orthogonal bases, an integration operation is performed on the optical signal output by the modulator to obtain a first result corresponding to the phase modulation electrode I currently applying the disturbance signal in the integration operation result;

[0010] Performing linear fitting on the first result and the bias control point to obtain a first fitting degree, and if the first fitting degree does not belong to a preset fitting interval, adjusting the amplitude of the disturbance signal until the recalculated first fitting degree belongs to the preset fitting interval, thereby obtaining an ideal disturbance signal amplitude for applying the phase modulation electrode I;

[0011] After selecting a phase modulation electrode Q to apply a disturbance signal, the ideal disturbance signal amplitude applied to the phase modulation electrode Q is obtained in the same manner as the ideal disturbance signal amplitude applied to the phase modulation electrode I.

[0012] Preferably, it further comprises a phase modulation electrode P, wherein the phase modulation electrode P is located on the transmission waveguide after the second waveguide and the third waveguide are combined, wherein the first waveguide is further combined with the transmission waveguide provided with the phase modulation electrode P.

[0013] Preferably, the bias voltages on the phase modulation electrode I, the phase modulation electrode Q and the phase modulation electrode P are respectively expressed as , and , the corresponding modulator output sampling result is:

[0014] ;

[0015] Wherein, the subscript i represents the bias voltage set for the i-th time, and t is a time parameter; wherein the sampling frequency is an integer multiple of the frequency of the disturbance signal; when the disturbance signal is applied to the phase modulation electrode I, and the phase modulation electrode Q and the phase modulation electrode P are still applied with the initial bias control voltage, the It is composed of the initial bias control point and the disturbance signal superposition; is the initial bias control point; is the initial bias control point.

[0016] Preferably, the frequency of the constructed pair of orthogonal bases is the same as the sampling rate of the modulator output optical signal. For the phase modulation electrode I, the corresponding orthogonal base is expressed as:

[0017] ;

[0018] ;

[0019] in, The fundamental phase of the orthogonal basis.

[0020] Preferably, for the phase modulation electrode Q, the corresponding orthogonal basis is expressed as:

[0021] ;

[0022] ;

[0023] in, The fundamental phase of the orthogonal basis.

[0024] Preferably, the first fitness is , the preset fitting interval is: .

[0025] Preferably, the disturbance signal amplitudes of the phase modulation electrode I and the phase modulation electrode Q are obtained respectively. and After that, turn on the automatic real-time locking function.

[0026] Preferably, the amplitude applied to the phase modulation electrode I is , calculate the integral value of the current phase modulation electrode I bias voltage and in, and The sampling results are and and Points earned;

[0027] right A linear fit is performed, and its slope is the same direction locking coefficient ;right Perform a linear fit, whose slope is the disturbance signal amplitude ;

[0028] When the modulator voltage deviates from the NULL point, the relevant integral result and Will no longer be equal to 0, get the integral result under the current bias and , and according to and Calculate the bias voltage adjustment value of the phase modulation electrode I .

[0029] Preferably, a disturbance is applied to the phase modulation electrode Q and an integral value is obtained, and a bias adjustment amount of the phase modulation electrode Q is calculated;

[0030] The frequencies applied to the phase modulation electrodes I and Q are The disturbance is detected and the integral value is obtained to calculate the bias adjustment amount of the phase modulation electrode P.

[0031] In a second aspect, the present invention further provides a control device for a bias operating point of a modulator, which is used to implement the control method for the bias operating point of a modulator described in the first aspect, and the device comprises:

[0032] At least one processor; and a memory in communication with the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the processor to execute the method for controlling the bias operating point of the modulator described in the first aspect.

[0033] The present invention applies a disturbance signal related to the bias voltage to the phase modulation electrode of the silicon-based optical modulator, and detects the amplitude of the signal component with the same frequency as the applied disturbance signal in the output signal of the modulator, thereby achieving simple and rapid locking and maintenance of the bias operating point of the silicon-based optical modulator, reducing the locking influence caused by the disturbance signal amplitude and improving the control accuracy.

[0034] In the preferred implementation of the present invention, by controlling the amplitude of the disturbance signal, the influence of the control algorithm on the locking can be greatly reduced, and the final operation stability can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 is a schematic diagram of a control architecture of a bias operating point of a modulator provided by an embodiment of the present invention;

[0037] Figure 2 It is a schematic flow chart of a method for controlling a bias operating point of a modulator provided by an embodiment of the present invention;

[0038] Figure 3 is a schematic diagram of a control architecture of a bias operating point of a modulator provided by an embodiment of the present invention;

[0039] Figure 4 is a schematic diagram of a control architecture of a bias operating point of a modulator provided by an embodiment of the present invention;

[0040] Figure 5 is a schematic diagram of a control architecture of a bias operating point of a modulator provided by an embodiment of the present invention;

[0041] Figure 6 It is a schematic flow chart of a method for controlling a bias operating point of a modulator provided by an embodiment of the present invention;

[0042] Figure 7 It is a calculation curve effect diagram of a bias operating point of a modulator provided by an embodiment of the present invention;

[0043] Figure 8 It is a schematic diagram of the structure of a control device for the bias operating point of a modulator provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0045] In the description of the present invention, the terms "inside", "outside", "longitudinal", "lateral", "upper", "lower", "top", "bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention.

[0046] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0047] Embodiment 1:

[0048] Embodiment 1 of the present invention provides a method for controlling the bias operating point of a modulator, such as Figure 1 As shown, when the phase modulation electrode of the modulator includes a phase modulation electrode I located on the first waveguide and a phase modulation electrode Q located on the second waveguide, as shown in FIG. Figure 2 As shown, the control method includes:

[0049] In step 201, an initial bias control point is set for the phase modulation electrode I and the phase modulation electrode Q, and the phase modulation electrode I and the phase modulation electrode Q are selected one by one as the phase modulation electrodes for applying a disturbance signal.

[0050] The initial bias control point and the disturbance signal constitute the bias control point of the corresponding phase modulation electrode. In an embodiment of the present invention, the initial bias control point is a DC control voltage, and the disturbance signal is a periodically changing voltage signal.

[0051] In step 202, after a phase modulation electrode I is selected to apply a disturbance signal, an integration operation is performed on the optical signal output by the modulator using a pair of constructed orthogonal bases to obtain a first result corresponding to the phase modulation electrode I currently applying the disturbance signal in the integration operation result.

[0052] The first result described here does not represent a specific order relationship, but is merely the first object to appear in the text description, and the limitation of “first” is made for the convenience of distinguishing it from other subsequent results from different processes.

[0053] In step 203, a linear fit is performed on the first result and the bias control point to obtain a first degree of fit. If the first degree of fit does not belong to the preset fitting interval, the amplitude of the disturbance signal is adjusted until the recalculated first degree of fit belongs to the preset fitting interval, thereby obtaining an ideal disturbance signal amplitude for applying the phase modulation electrode I.

[0054] In the embodiments of the present invention, the settings of the parameters or intervals involved can be calculated based on the specific application scenario combined with the test requirements. Therefore, based on the fitting intervals disclosed in the subsequent embodiments of the present invention for specific scenarios, other fitting intervals obtained by those skilled in the art after simple adjustments should also fall within the effective protection scope of the present invention. For example, the first degree of fit is , the preset fitting interval is: .

[0055] In step 204, after a phase modulation electrode Q is selected to apply a disturbance signal, the ideal disturbance signal amplitude applied to the phase modulation electrode Q is obtained in the same manner as the ideal disturbance signal amplitude applied to the phase modulation electrode I is obtained.

[0056] Here, it is equivalent to taking the phase modulation electrode Q as the main body and re-performing a round of step 202-step 203 process, so as to obtain the ideal disturbance signal amplitude applied to the phase modulation electrode Q. Figure 3 As shown, a typical device structure that can be used to run the above-mentioned step 201-step 204 method process is given, wherein the optical signal output by the modulator is collected by the MPD, and is processed by the filter amplifier and the ADC in sequence, and then obtained by the MCU, thereby completing the relevant recursive calculation process in step 202 and step 203.

[0057] The embodiment of the present invention applies a disturbance signal related to the bias voltage to the phase modulation electrode of the silicon-based optical modulator, and detects the amplitude of the signal component with the same frequency as the added disturbance signal in the output signal of the modulator, so as to achieve simple and rapid locking and maintenance of the bias operating point of the silicon-based optical modulator, reduce the locking effect caused by the amplitude of the disturbance signal, and improve the control accuracy. By controlling the amplitude of the disturbance signal, the present invention can greatly reduce the influence of the control algorithm on the locking and improve the final operation stability.

[0058] like Figure 4 As shown, as a more expressive complex application scenario after the implementation method of embodiment 1 of the present invention is proposed, it also includes a phase modulation electrode P, and the phase modulation electrode P is located on the transmission waveguide after the second waveguide and the third waveguide are combined, wherein the first waveguide is further combined with the transmission waveguide provided with the phase modulation electrode P. Here, it should be emphasized that in the embodiment of the present invention, the phase modulation electrode P is implemented, such as Figure 4In the illustrated architecture, no disturbance signal is applied to the corresponding phase modulation electrode P, but an initial bias control point is applied to the phase modulation electrode I and the phase modulation electrode Q as well.

[0059] At this point, the amplitude of the disturbance signal of the phase modulation electrode I can be obtained by tracing back the same method as above for obtaining the ideal disturbance signal amplitude of the phase modulation electrode I. ; and the amplitude of the disturbance signal of the phase modulation electrode Q is obtained in the same way as the ideal disturbance signal amplitude of the phase modulation electrode Q Of the two, the most simple and direct method is to make the disturbance signal and the sampled frequency signal the same. In an optional method, the sampling frequency can be an integer multiple of the disturbance signal frequency.

[0060] In the embodiment of the present invention, Figure 4 Taking the architecture of as an example, the bias voltages on the phase modulation electrode I, the phase modulation electrode Q and the phase modulation electrode P are respectively expressed as , and , the corresponding modulator output sampling result is:

[0061] ;

[0062] Wherein, the subscript i represents the bias voltage set for the i-th time, t is the time parameter, which is a parameter item inherited from the disturbance signal; wherein the sampling frequency is an integer multiple of the disturbance signal frequency; when the disturbance signal is applied to the phase modulation electrode I, and the phase modulation electrode Q and the phase modulation electrode P are still applying the initial bias control voltage, the It is composed of the initial bias control point and the disturbance signal superposition; is the initial bias control point; is the initial bias control point. Similarly, when the disturbance signal is applied to the phase modulation electrode Q, and the initial bias control voltage is still applied to the phase modulation electrode I and the phase modulation electrode P, the It is composed of the initial bias control point and the disturbance signal superposition; is the initial bias control point; is the initial bias control point; and similarly, when the phase modulation electrode I and the phase modulation electrode P are applied with disturbance signals of frequencies f1 and f2, respectively, and the phase modulation electrode P is still applied with the initial bias control voltage, the It is composed of the initial bias control point and the disturbance signal with frequency f1; It is composed of the initial bias control point and the disturbance signal with a frequency of f2; It is only its own initial bias control point. When the phase modulation electrode I and the phase modulation electrode P apply disturbance signals with frequencies f1 and f2 respectively, it is also necessary to ensure that the corresponding output result sampling signal is the combined frequency of f1 and f2, for example, the sampling frequency f=f1+f2.

[0063] In the embodiment of the present invention, the frequency of the constructed pair of orthogonal bases is the same as the sampling rate of the optical signal output by the modulator. For the phase modulation electrode I, the corresponding orthogonal base is expressed as:

[0064] ;

[0065] ;

[0066] in, It should be noted that IBase and QBase here have no direct relationship with the corresponding phase modulation electrode I and phase modulation electrode Q. They are expressions of the orthogonal basis. When they are applied to the phase modulation electrode I, IBase and QBase are added with corresponding subscripts, which are specifically expressed as IBase I and QBase I When applied to the phase-modulated electrode Q, the corresponding subscripts are added to IBase and QBase, and are specifically expressed as IBase Q and QBase q .

[0067] Therefore, for the phase-modulated electrode Q, the corresponding orthogonal basis is expressed as:

[0068] ;

[0069] ;

[0070] in, The fundamental phase of the orthogonal basis.

[0071] In combination with the embodiment of the present invention, after the disturbance signal amplitude obtained in the embodiment of the present invention, a solution for further improving the effectiveness of bias operating point control in the actual use scenario of the modulator is provided. After respectively obtaining the disturbance signal amplitude of the phase modulation electrode I and the phase modulation electrode Q, and After that, turn on the automatic real-time locking function, such as Figure 6 As shown, specifically including:

[0072] In step 301, the phase modulation electrode I applies an amplitude of , calculate the integral value CI under the current phase modulation electrode I bias voltage Ii and CQ Ii , where CIIi and CQ Ii The sampling results P are outi (t) with IBase I (t) and QBase I (t) Points gained.

[0073] The corresponding integral solution process is expressed as the following expression:

[0074] ;

[0075] ;

[0076] In step 302, Bias I,i and CI Ii A linear fit is performed, and its slope is the same direction locking coefficient ICoeff I ; for Bias I,i and CQ Ii Perform a linear fit, whose slope is the disturbance signal amplitude QCoeff I .

[0077] In step 303, when the modulator voltage deviates from the NULL point, its correlation integral result CI Ii and CQ Ii Will no longer be equal to 0, and obtain the integral result CI under the current bias voltage Ii , CQ Ii , calculate the bias adjustment value △Bias of the phase modulation electrode I I .

[0078] ;

[0079] in, It means the same direction locking coefficient of the phase modulation electrode I; It means the same direction locking coefficient of the phase modulation electrode Q, which represents the speed at which the integral value changes with the bias voltage; and You can take Figure 7 To understand, Figure 7 middle and It can be understood as the area of ​​the triangle formed by the corresponding oblique line and the polar coordinate axis, and they are divided by and Then, the respective voltage values ​​are obtained, and the bias adjustment value △Bias of the phase modulation electrode I is obtained by averaging. I .

[0080] A disturbance is applied to the phase modulation electrode Q and an integral value is obtained, and a bias adjustment amount of the phase modulation electrode Q is calculated;

[0081] At this time, the bias adjustment value △Bias of the phase modulation electrode Q is calculated Q .

[0082] ;

[0083] in, It means the same direction locking coefficient of the phase modulation electrode I; It means the same direction locking coefficient of the phase modulation electrode Q, which represents the speed at which the integral value changes with the bias voltage; and It can be understood as the area of ​​the triangle formed by the corresponding oblique line and the polar coordinate axis, and they are divided by and Then we get the respective voltage values, and then we get the bias adjustment value △Bias of the phase modulation electrode Q by averaging. Q .

[0084] The frequencies applied to the phase modulation electrodes I and Q are The disturbance of the phase modulation electrode P is obtained by taking the integral value and calculating the bias adjustment of the phase modulation electrode P. Unlike the previous calculation of the bias adjustment of the phase modulation electrode I and the calculation of the bias adjustment of the phase modulation electrode Q using the same calculation method of the bias adjustment of the phase modulation electrode I, when calculating the bias adjustment of the phase modulation electrode P, no disturbance signal is applied to the phase modulation electrode P, but only an initial bias control point is applied to the phase modulation electrode P. At this time, relying on the above derivation process, it is compared with solving the bias adjustment of the phase modulation electrode I △Bias I and the bias adjustment value △Bias of the phase modulation electrode Q Q More differences are in The corresponding orthogonal basis and the final calculated bias adjustment △Bias P The formulas can all be completed using the equivalent formulas above, so I will not go into details here.

[0085] If the present invention is applied in Figure 3 For the architecture shown, the corresponding bias adjustment amount calculation process can be implemented by simply deleting the relevant parts of the process details related to the phase-modulating electrode P given above. For the sake of simplicity in the content description, the above solution content directly describes the process based on the scenario including the phase-modulating electrode P.

[0086] Embodiment 2:

[0087] The embodiment of the present invention directly adopts a most typical architectural relationship to illustrate the most characteristic and complete solution implementation process, which is derived from the solution in Embodiment 1. However, the logical connection and description between the features are fully developed based on a specific scenario. Figure 5As shown, the embodiment of the present invention includes an IQ modulator, and the modulator is provided with phase modulation electrodes I and Q for adjusting the bias voltage of the Child MZI modulator, and the phase modulation electrode P is used to adjust the bias voltage of the Parent MZI modulator. The digital to analog converter (Digital to Analog Convertor, referred to as DAC) is used to apply a DC bias and a disturbance signal to the phase modulation electrode, and a part of the signal light is separated from the light output of the modulator to the monitor photodiode (Monitor Photo Diode, abbreviated as: MPD) to convert it into photocurrent, which is sampled by the analog-to-digital converter (Analog-to-digitalconverter, referred to as ADC) after filtering and amplification. The microcontroller unit (Microcontroller Unit, MCU) analyzes and processes the sampled data.

[0088] For the ideal modulator model, its normalized output can be expressed as:

[0089] ;

[0090] in: is the normalized modulator output optical power, is the normalized modulator bias voltage. Among them, the phase modulation electrode P will affect the phase difference between the optical signal after passing through the phase modulation electrode I and the optical signal after passing through the phase modulation electrode Q. The final light output will inevitably have an Show the parts that are relevant to all three.

[0091] The purpose of modulator bias control is to control the phase modulation electrodes I, Q, and P in real time so that the Child MZI modulator I and Q bias voltages are at the Null point and the Parent MZI modulator voltage is at the Quad point, that is, the normalized modulator operating voltage. They are equal to 1, 1, and 1 / 2 respectively.

[0092] By coarsely adjusting the modulator operating voltage through common methods such as minimum extinction ratio, the modulator bias voltage can be roughly near the operating point. The present invention obtains the orthogonal locking coefficient within the range near the operating point through the orthogonal locking method, which can realize the precise adjustment of the modulator bias voltage and the real-time locking of the operating point.

[0093] Taking the phase modulation electrode I as an example to illustrate the implementation principle of the present invention, the amplitude is applied to the phase modulation electrode I. ,frequency , the initial phase is The disturbance signal :

[0094] ;

[0095] At the same time, construct a pair of orthogonal bases with frequency f, expressed as:

[0096] ;

[0097] ;

[0098] When the orthogonal basis is selected, its sampling frequency is consistent with the ADC sampling rate.

[0099] The sampling result of the modulator optical signal is correlated with the orthogonal basis to obtain the integral result. , :

[0100] ;

[0101] ;

[0102] Since the disturbance is applied to the phase modulation electrode I at this time, and the phase modulation electrodes Q and P are set near the initial working point. In, only is time-dependent, while the remaining terms can be approximated as constants. Therefore, the integral value , Can be simplified to:

[0103] ;

[0104] ;

[0105] in is approximately a constant. In the present invention, the sampling frequency is selected as an integer multiple of the disturbance frequency, and the integration time is selected as an integer multiple of the disturbance signal period. Therefore , The constant component The integration result with the orthogonal basis is approximately 0. , Further simplified to:

[0106] ;

[0107] ;

[0108] Normalized bias voltage of phase modulation electrode I It can be expressed as:

[0109] ;

[0110] in, is the DC bias, is the disturbance signal;

[0111] Near the modulator operating point, A series expansion is performed, in which only the fundamental frequency component with the same orthogonal fundamental frequency contributes to the final correlation integral result, and other components can be ignored after integration over time. This is because for the sine function, sin(x) and sin(n*x) (n is not equal to 1) are both orthogonal, and the integrals with other frequency components over an integer number of fundamental frequency periods are all 0.

[0112] therefore, , It can be expressed as, which means that the integral value is related to the DC bias voltage point. The orthogonality of trigonometric functions is used, and other integral values ​​are 0. The expression is:

[0113] ;

[0114] ;

[0115] In a certain range near the initial bias control point of the phase modulation electrode I, several bias voltages are selected according to the voltage step length. , respectively obtain the relevant integral results , . Figure 7 It shows that within the range of normalized bias voltage, the integral result changes with In the small range near the NULL point, , Follow is approximately linear. And the intersection point between the two corresponds to the NULL point, at which point the integral result is theoretically 0.

[0116] right A linear fit is performed, and its slope is the same direction locking coefficient ;right Perform a linear fit, whose slope is the orthogonal locking coefficient .from Figure 7 It can be seen that when the modulator voltage deviates from the NULL point, the relevant integral result , will no longer be equal to 0. By obtaining the integral result under the current bias voltage, the final bias voltage can be calculated.

[0117] ;

[0118] At the same time, the same direction locking factor is used , orthogonal locking coefficient Obtaining the voltage regulation offset can reduce the impact of sampling errors. This stage is the follow-up to the previous stage, and is to perform bias locking after determining the disturbance amplitude.

[0119] Related points results , It is positively correlated with the amplitude of the disturbance signal. In practical applications, due to the influence of circuit background noise, sampling error, etc., a too small disturbance signal amplitude will cause the co-directional locking coefficient to , orthogonal locking coefficient , cannot correctly reflect the position of the bias voltage point; and when the disturbance signal amplitude is too large, the impact is very sensitive when high-order code types such as 16QAM are applied, which will cause unstable post-correction errors. Therefore, in practice, it is necessary to adjust the appropriate disturbance signal amplitude to ensure the co-directional locking coefficient. , orthogonal locking coefficient Not in the extreme cases above.

[0120] Furthermore, the present invention proposes to adjust the amplitude of the disturbance signal so that the amplitude of the disturbance signal The appropriate size not only reduces the amplitude of the disturbance signal, but also ensures that the fitting curve has a high degree of fit. , adjust the amplitude of the disturbance signal (Generally, the larger the disturbance signal amplitude, the better the fitting degree, the more accurate the bias voltage adjustment amount, and the larger the disturbance signal amplitude, the greater the system cost), and re-perform the integral fitting step to obtain the fitting degree of the phase modulation electrode I again. , until .

[0121] According to the control method of the phase modulation electrode I, the phase modulation electrode Q and the phase modulation electrode P can be locked to the NULL point and the Quad point respectively. It should be noted that when the phase modulation electrode P is locked, a disturbance signal needs to be applied to I and Q at the same time, and the constructed orthogonal base frequency is the sum of the two disturbance signal frequencies.

[0122] Embodiment 3:

[0123] like Figure 8 , which is a schematic diagram of the structure of the control device of the bias operating point of the modulator according to an embodiment of the present invention. The control device of the bias operating point of the modulator according to this embodiment includes one or more processors 21 and a memory 22. Figure 8 A processor 21 is taken as an example.

[0124] The processor 21 and the memory 22 may be connected via a bus or other means. Figure 8 The example of connecting through bus is taken in the following.

[0125] The memory 22 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs and non-volatile computer executable programs, such as the method for controlling the bias operating point of the modulator in Example 1. The processor 21 executes the method for controlling the bias operating point of the modulator by running the non-volatile software programs and instructions stored in the memory 22.

[0126] The memory 22 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage devices. In some embodiments, the memory 22 may optionally include a memory remotely arranged relative to the processor 21, and these remote memories may be connected to the processor 21 via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0127] The program instructions / modules are stored in the memory 22, and when executed by the one or more processors 21, the method for controlling the bias operating point of the modulator in the above embodiment 1 is executed, for example, the above described method is executed. Figure 2 , Figure 5 and Figure 6 The steps shown.

[0128] It is worth noting that the information interaction, execution process, etc. between the modules and units within the above-mentioned devices and systems are based on the same concept as the processing method embodiment of the present invention. The specific contents can be found in the description of the method embodiment of the present invention and will not be repeated here.

[0129] A person skilled in the art may understand that all or part of the steps in the various methods of the embodiments may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, and the storage medium may include: a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk, etc.

[0130] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for controlling a bias operating point of a modulator, characterized in that: When the phase modulation electrode of the modulator includes a phase modulation electrode I located on the first waveguide and a phase modulation electrode Q located on the second waveguide, the control method includes: Setting an initial bias control point for the phase modulation electrode I and the phase modulation electrode Q, and selecting the phase modulation electrode I and the phase modulation electrode Q one by one as the phase modulation electrode to which the disturbance signal is applied; wherein the initial bias control point and the disturbance signal constitute the bias control point of the corresponding phase modulation electrode; After selecting a phase modulation electrode I to apply a disturbance signal, using a pair of constructed orthogonal bases, performing an integration operation on the optical signal output by the modulator and the orthogonal base, and obtaining a first result corresponding to the phase modulation electrode I currently applying the disturbance signal in the integration operation result; Performing linear fitting on the first result and the bias control point to obtain a first fitting degree, and if the first fitting degree does not belong to a preset fitting interval, adjusting the amplitude of the disturbance signal until the recalculated first fitting degree belongs to the preset fitting interval, thereby obtaining an ideal disturbance signal amplitude for applying the phase modulation electrode I; After selecting a phase modulation electrode Q to apply a disturbance signal, the ideal disturbance signal amplitude applied to the phase modulation electrode Q is obtained in the same manner as the ideal disturbance signal amplitude applied to the phase modulation electrode I; The frequency of the constructed pair of orthogonal bases is the same as the sampling rate of the modulator output optical signal. For the phase modulation electrode I, the corresponding orthogonal base is expressed as: ； ； in, The fundamental phase of the orthogonal basis; For the phase-modulated electrode Q, the corresponding orthogonal basis is expressed as: ； ； in, The fundamental phase of the orthogonal basis.

2. The method for controlling the bias operating point of a modulator according to claim 1, characterized in that: It also includes a phase modulation electrode P, which is located on the transmission waveguide after the second waveguide and the third waveguide are combined, wherein the first waveguide is further combined with the transmission waveguide on which the phase modulation electrode P is arranged.

3. The method for controlling the bias operating point of a modulator according to claim 2, characterized in that: The bias voltages on the phase modulation electrode I, the phase modulation electrode Q and the phase modulation electrode P are respectively expressed as , and , the corresponding modulator output sampling result is: ； Wherein, the subscript i represents the bias voltage set for the i-th time, and t is a time parameter; wherein the sampling frequency is an integer multiple of the frequency of the disturbance signal; when the disturbance signal is applied to the phase modulation electrode I, and the phase modulation electrode Q and the phase modulation electrode P are still applied with the initial bias control voltage, the It is composed of the initial bias control point and the disturbance signal superposition; is the initial bias control point; is the initial bias control point.

4. The method for controlling the bias operating point of a modulator according to any one of claims 1 to 3, characterized in that: The first fitness is , the preset fitting interval is: .

5. The method for controlling the bias operating point of a modulator according to claim 1, characterized in that: The disturbance signal amplitudes of the phase modulation electrode I and the phase modulation electrode Q are obtained respectively. and After that, turn on the automatic real-time locking function.

6. The method for controlling the bias operating point of a modulator according to claim 5, characterized in that: The amplitude applied to the phase modulation electrode I is , calculate the integral value of the current phase modulation electrode I bias voltage and in, and The sampling results are and and Points earned; right A linear fit is performed, and its slope is the same direction locking coefficient ;right Perform a linear fit, whose slope is the disturbance signal amplitude ; When the modulator voltage deviates from the NULL point, the relevant integral result and Will no longer be equal to 0, get the integral result under the current bias and , and according to and Calculate the bias voltage adjustment value of the phase modulation electrode I .

7. A control device for a bias operating point of a modulator, characterized in that: The device comprises: At least one processor; and a memory in communication with the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the processor to execute the method for controlling the bias operating point of the modulator as described in any one of claims 1-6.

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