Signal modulation method and signal modulation circuit

Abstract

The embodiment of the invention discloses a signal modulation method and a signal modulation circuit, and the method comprises the steps: carrying out the modulation of a to-be-modulated signal obtained from a light source, and obtaining a first modulation signal; measuring a scattering parameter corresponding to the first modulation signal to obtain a first measurement value of the scattering parameter; under the condition that the first measurement value does not meet the modulation condition, a first adjustment amount corresponding to the working parameter of the signal modulation circuit is determined based on the first measurement value of the scattering parameter; the scattering parameter is used for describing a transmission characteristic and / or a reflection characteristic between the signal to be modulated and the first modulation signal; adjusting the working parameter based on the first adjustment amount to obtain a target working parameter; and modulating the to-be-modulated signal based on the target working parameter.

Description

Technical Field

[0001] The present application relates to but is not limited to the field of optical communication technology, and in particular to a signal modulation method and a signal modulation circuit. Background Art

[0002] Mach-Zehnder modulator (MZM) plays a key role in optical communication systems. The accuracy of its working point directly affects the efficiency of signal modulation. In related technologies, the adjustment method of the working point usually relies on manual operation, which is inefficient and difficult to ensure accuracy and stability. Summary of the invention

[0003] In view of this, the embodiments of the present application at least provide a signal modulation method and a signal modulation circuit.

[0004] The technical solution of the embodiment of the present application is implemented as follows:

[0005] The present application provides a signal modulation method, including:

[0006] Modulating the signal to be modulated obtained from the light source to obtain a first modulated signal;

[0007] Measuring a scattering parameter corresponding to the first modulation signal to obtain a first measurement value of the scattering parameter; and determining a first adjustment amount corresponding to an operating parameter of the signal modulation circuit based on the first measurement value of the scattering parameter when the first measurement value does not meet the modulation condition; the scattering parameter is used to describe the transmission characteristics and / or reflection characteristics between the signal to be modulated and the first modulation signal;

[0008] Based on the first adjustment amount, the operating parameter is adjusted to obtain a target operating parameter;

[0009] Based on the target operating parameters, the signal to be modulated is modulated.

[0010] The embodiment of the present application provides a signal modulation circuit, including a modulator, a vector network analyzer, a controller and a driving circuit, wherein:

[0011] A modulator, used to modulate the signal to be modulated obtained from the light source to obtain a first modulated signal;

[0012] A vector network analyzer is used to measure a scattering parameter corresponding to the first modulated signal to obtain a first measured value of the scattering parameter;

[0013] A controller, configured to determine, when the first measurement value does not satisfy the modulation condition, a first adjustment amount corresponding to an operating parameter of the signal modulation circuit based on the first measurement value of the scattering parameter; the scattering parameter is used to describe a transmission characteristic and / or a reflection characteristic between a signal to be modulated and the first modulation signal;

[0014] A driving circuit, used for adjusting the operating parameter based on the first adjustment amount to obtain a target operating parameter;

[0015] The modulator is further used to modulate the signal to be modulated based on the target working parameter.

[0016] An embodiment of the present application provides a chip, including the above-mentioned signal modulation circuit.

[0017] In the embodiment of the present application, a signal to be modulated is modulated to obtain a first modulated signal, and a scattering parameter corresponding to the first modulated signal is measured to obtain a first measurement value; when the first measurement value does not meet the modulation condition, an adjustment amount corresponding to the working parameter of the signal modulation circuit is determined according to the first measurement value; the working parameter is adjusted according to the adjustment amount, and the signal to be modulated is modulated according to the target working parameter obtained after the adjustment. In this way, when the measured value of the scattering parameter does not meet the modulation condition, the working parameter is adjusted to obtain the target working parameter, so that the signal modulation circuit modulates the signal to be modulated under the target working parameter, thereby improving the efficiency and accuracy of signal modulation.

[0018] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and are not intended to limit the technical solutions of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present application and are used together with the specification to illustrate the technical solution of the present application.

[0020] Figure 1 A schematic diagram of an implementation flow of a signal modulation method provided in an embodiment of the present application;

[0021] Figure 2 A schematic diagram of the structure of a signal modulation circuit provided in an embodiment of the present application;

[0022] Figure 3 A schematic diagram of a signal modulation system for automatically controlling and adjusting the optimal operating point of a silicon light modulator provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions of the present application are further elaborated in detail below in conjunction with the drawings and embodiments. The described embodiments should not be regarded as limiting the present application. All other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0024] In the following description, reference is made to “some embodiments”, which describe a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0025] The terms "first / second / third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It is understandable that "first / second / third" can be interchanged with a specific order or sequence where permitted so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing this application and are not intended to limit this application.

[0027] The present application provides a signal modulation method. Figure 1 A schematic diagram of a signal modulation method for implementing the present invention is shown in FIG. Figure 1 As shown, the method includes the following steps S101 to S104:

[0028] Step S101: modulating a signal to be modulated obtained from a light source to obtain a first modulated signal;

[0029] Here, the light source may be at least one of a laser, a light emitting diode, an optical amplifier, and the like.

[0030] The signal to be modulated is an optical signal sent by the light source and is to be modulated by the modulator.

[0031] The first modulation signal is a modulation signal obtained by modulating the signal to be modulated by the modulator.

[0032] In some implementations, the modulator can be a Mach Zehnder modulator (MZM).

[0033] In some implementations, an optical signal emitted by a light source is used as a signal to be modulated, input into a modulator via an input port of the modulator for modulation, and an output port of the modulator outputs a modulated first modulated signal.

[0034] Step S102: measuring a scattering parameter corresponding to the first modulated signal to obtain a first measured value of the scattering parameter; and determining a first adjustment amount corresponding to an operating parameter of the signal modulation circuit based on the first measured value of the scattering parameter when the first measured value does not meet a modulation condition; the scattering parameter is used to describe a transmission characteristic and / or a reflection characteristic between the signal to be modulated and the first modulated signal;

[0035] Here, the scattering parameter (S parameter) is a parameter that describes the characteristics of a linear two-port network. In the embodiment of the present application, the scattering parameter can reflect the amplitude and phase relationship between the input and output optical signals of the modulator.

[0036] The operating parameters may include but are not limited to at least one of input optical power, bias voltage, etc.

[0037] In some embodiments, the scattering parameters include an S21 amplitude parameter, an S21 phase parameter, and an S11 reflection parameter.

[0038] Specifically, the S21 amplitude parameter reflects the change in the transmission intensity of the optical signal from the input port to the output port of the modulator, that is, the gain or attenuation of the optical signal from the input port to the output port. Therefore, the larger the S21 amplitude, the higher the power transmission efficiency of the optical signal from the input port to the output port, that is, the smaller the signal loss.

[0039] The S21 phase parameter describes the phase change of the optical signal from the input port to the output port of the modulator, which can indicate the delay or advance of the phase of the optical signal during transmission. If there is a linear relationship between the phase change and the applied driving signal (such as bias voltage), the phase information of the optical signal during the modulation process can be accurately transmitted, reducing signal distortion.

[0040] The S11 reflection parameter indicates the reflection coefficient of the input port of the modulator. If the S11 reflection parameter is large, it means that the input optical signal has more reflections, which causes the working point of the modulator to shift. Ideally, the S11 parameter should be as small as possible so that the input signal to be modulated can effectively enter the modulator for modulation.

[0041] In some implementations, a vector network analyzer (VNA) is used to measure the scattering parameter to obtain a first measurement value.

[0042] In some embodiments, before measuring the scattering parameter corresponding to the first modulated signal, the first modulated signal is converted from an optical signal to an electrical signal.

[0043] In some implementations, whether the first measured value satisfies the modulation condition can be determined by determining whether the modulator reaches an optimal working point; the modulation efficiency of the modulator at the optimal working point is the highest. The working parameters can be adjusted iteratively multiple times according to the adjustment amount, so that the modulator gradually approaches the optimal working point, and finally modulates the input optical signal at the optimal working point, thereby improving the efficiency and accuracy of signal modulation.

[0044] In some embodiments, a vector network analyzer is used to measure scattering parameters to obtain amplitude measurement values ​​corresponding to the S21 amplitude parameter, phase measurement values ​​corresponding to the S21 phase parameter, and / or reflection measurement values ​​corresponding to the S11 reflection parameter; when the amplitude measurement values, phase measurement values, and reflection measurement values ​​have measurement values ​​that do not meet the corresponding modulation conditions, a first adjustment amount of the operating parameters of the signal modulation circuit is calculated based on the amplitude measurement values, phase measurement values, and / or reflection measurement values.

[0045] Step S103: adjusting the operating parameter based on the first adjustment amount to obtain a target operating parameter;

[0046] Here, the target operating parameter is the operating parameter when the measured value of the corresponding scattering parameter meets the modulation condition after the operating parameter is adjusted according to the first adjustment amount.

[0047] In some implementations, the driving circuit adjusts parameters such as bias voltage and input optical power according to the first adjustment amount.

[0048] In some implementations, the bias voltage is adjusted to change the drive signal applied by the drive circuit to the modulator.

[0049] In some embodiments, the working parameter is adjusted according to a first adjustment amount to obtain the first working parameter; and the modulated signal is modulated according to the first working parameter to obtain a second modulated signal; the scattering parameter corresponding to the second modulated signal is measured to obtain a second measurement value, and when the second measurement value meets the modulation condition, the first working parameter is determined as the target working parameter; when the second measurement value does not meet the modulation condition, the second adjustment amount of the working parameter is determined according to the second measurement value; and according to the second adjustment amount, the working parameter is iteratively adjusted multiple times until the target working parameter is obtained when the measurement value meets the modulation condition.

[0050] Step S104: modulating the signal to be modulated based on the target operating parameters.

[0051] In some implementations, under target operating parameters, the modulation efficiency is highest when the signal to be modulated is modulated.

[0052] In some embodiments, during the signal modulation process, it is detected in real time whether the measured value of the scattering parameter corresponding to the modulated signal meets the modulation conditions. If the modulation conditions are not met, the operating parameters of the signal modulation circuit are adjusted through the above process until the target operating parameters are obtained.

[0053] In the embodiment of the present application, a signal to be modulated is modulated to obtain a first modulated signal, and a scattering parameter corresponding to the first modulated signal is measured to obtain a first measurement value; when the first measurement value does not meet the modulation condition, an adjustment amount corresponding to the working parameter of the signal modulation circuit is determined according to the first measurement value; the working parameter is adjusted according to the adjustment amount, and the signal to be modulated is modulated according to the target working parameter obtained after the adjustment. In this way, when the measured value of the scattering parameter does not meet the modulation condition, the working parameter is adjusted to obtain the target working parameter, so that the signal modulation circuit modulates the signal to be modulated under the target working parameter, thereby improving the efficiency and accuracy of signal modulation.

[0054] In some embodiments, the first measurement value includes an amplitude measurement value, a phase measurement value, and a reflection measurement value; and the measuring of the scattering parameter corresponding to the first modulated signal in step S102 to obtain the first measurement value of the scattering parameter may include at least one of the following steps S111 to S113:

[0055] Step S111: determining an amplitude measurement value of the scattering parameter based on the amplitude of the signal to be modulated and the amplitude of the first modulated signal;

[0056] Here, the amplitude measurement value may represent a change in the transmission strength of a signal from an input port to an output port of the modulator. Therefore, the amplitude measurement value may be determined according to the amplitude of the signal to be modulated and the amplitude of the first modulating signal.

[0057] Step S112: determining a phase measurement value of the scattering parameter based on the phase of the signal to be modulated and the phase of the first modulated signal;

[0058] Here, the phase measurement value may represent a phase change of a signal from an input port to an output port of the modulator, and therefore, the phase measurement value may be determined according to the phase of the signal to be modulated and the phase of the first modulating signal.

[0059] Step S113: determining a reflection measurement value of the scattering parameter based on the signal to be modulated and a reflection signal corresponding to the signal to be modulated.

[0060] Here, the reflection measurement value may represent the reflection condition of the input port of the modulator, and therefore, the reflection measurement value is determined according to the signal power of the signal to be modulated and the signal power of the reflected signal corresponding to the signal to be modulated.

[0061] In some implementations, a ratio between a signal power of a reflected signal corresponding to the signal to be modulated and a signal power of the signal to be modulated is determined as the reflection measurement value.

[0062] The step S102 of determining the first adjustment amount corresponding to the operating parameter of the signal modulation circuit based on the first measured value of the scattering parameter may include the following step S114:

[0063] Step S114: Determine a first adjustment amount of the operating parameter based on the amplitude measurement value, the phase measurement value and / or the reflection measurement value.

[0064] In some implementations, the first adjustment amount of the operating parameter may be determined based on one, two, or three of the amplitude measurement value, the phase measurement value, and the reflection measurement value.

[0065] In the embodiment of the present application, the first measurement value includes an amplitude measurement value, a phase measurement value, and a reflection measurement value; the amplitude measurement value is determined according to the amplitude of the signal to be modulated and the amplitude of the first modulation signal; the phase measurement value is determined according to the phase of the signal to be modulated and the phase of the first modulation signal; the reflection measurement value is determined according to the signal to be modulated and the reflection signal corresponding to the signal to be modulated; the first adjustment amount of the working parameter is determined according to the amplitude measurement value, the phase measurement value, and / or the reflection measurement value. In this way, the influence of the amplitude measurement value, the phase measurement value, and / or the reflection measurement value on the working parameter is comprehensively considered, so that the first adjustment amount of the working parameter obtained is more accurate.

[0066] In some embodiments, the signal modulation circuit includes a modulator, and the method further includes the following step S121:

[0067] Step S121: when the modulator has not reached the optimal operating point, determining that the first measurement value does not satisfy the modulation condition; the modulation efficiency of the modulator is highest when it reaches the optimal operating point.

[0068] In some embodiments, whether the modulator reaches an optimal operating point is determined based on the first measurement value and a reference value of the scattering parameter.

[0069] In some implementations, the reference values ​​of the scattering parameters include amplitude reference values, phase reference values ​​and / or reflection reference values, which are determined through theoretical analysis, simulation or experimental calibration, and the reference values ​​are stored in a memory.

[0070] During the signal modulation process, the measured value of the scattering parameter is compared with the reference value stored in the memory. If the conditions for the modulator to reach the optimal operating point are not met, the operating parameters of the signal modulation circuit need to be adjusted.

[0071] In some implementations, the signal modulation circuit monitors in real time whether the modulator has reached an optimal operating point. If the optimal operating point has not been reached, the operating parameters of the signal modulation circuit are adjusted in real time so that the modulator can always operate at the optimal operating point.

[0072] In an embodiment of the present application, the signal modulation circuit includes a modulator, and when the modulator has not reached an optimal operating point, it is determined that the first measurement value does not meet the modulation condition, and the modulation efficiency of the modulator is the highest when the modulator reaches the optimal operating point. In this way, whether the first measurement value meets the modulation condition is determined by whether the modulator has reached the optimal operating point, so that when the first measurement value does not meet the modulation condition, the working parameters are adjusted, so that the modulator is close to or at the optimal operating point for signal modulation, thereby improving the modulation efficiency.

[0073] In some embodiments, the scattering parameters include amplitude parameters, phase parameters and reflection parameters; the above method further includes at least one of the following steps S131 to S133:

[0074] Step S131: when the amplitude measurement value corresponding to the amplitude parameter is less than the amplitude reference value, determining that the modulator has not reached the optimal operating point;

[0075] In some embodiments, when the scattering parameters include an amplitude parameter, it is determined that the modulator has reached an optimal operating point when the amplitude parameter is maximum and relatively stable within a certain frequency range without large fluctuations; the amplitude value at which the amplitude parameter is maximum and relatively stable within a certain frequency range is set as an amplitude reference value corresponding to the amplitude parameter; therefore, when the amplitude measurement value is less than the amplitude reference value, it is determined that the modulator has not reached the optimal operating point.

[0076] Step S132: when the phase measurement value corresponding to the phase parameter and the phase reference value do not satisfy a linear relationship, determining that the modulator has not reached an optimal operating point;

[0077] In some embodiments, when the scattering parameters include phase parameters, the modulator has a linear relationship between the change in amplitude and the applied driving signal (such as bias voltage) near the optimal operating point. Therefore, the phase change of the applied driving signal is set to the phase reference value corresponding to the phase parameter. When the linear relationship between the phase measurement value and the phase reference value is not satisfied, it is determined that the modulator has not reached the optimal operating point.

[0078] Step S133: when the reflection measurement value corresponding to the reflection parameter is greater than the reflection reference value, determining that the modulator has not reached the optimal working point.

[0079] In some embodiments, when the scattering parameters include a reflection parameter, if the reflection parameter is too large, it means that the modulated signal input to the modulator has more reflections, resulting in a shift in the operating point of the modulator. Therefore, a reflection reference value corresponding to the reflection parameter can be set. When the reflection measurement value is greater than the reflection reference value, it is determined that the modulator has not reached the optimal operating point.

[0080] In the embodiment of the present application, the scattering parameters include an amplitude parameter, a phase parameter, and a reflection parameter. When the amplitude measurement value corresponding to the amplitude parameter is less than the amplitude reference value, it is determined that the modulator has not reached the optimal operating point; when the phase measurement value corresponding to the phase parameter and the phase reference value do not satisfy a linear relationship, it is determined that the modulator has not reached the optimal operating point; when the reflection measurement value corresponding to the reflection parameter is greater than the reflection reference value, it is determined that the modulator has not reached the optimal operating point. In this way, according to the amplitude measurement value and the amplitude reference value, the phase measurement value and the phase reference value, and the reflection measurement value and the reflection reference value, the influence of the amplitude parameter, the phase parameter, and the reflection parameter on whether the modulator is at the optimal operating point is considered respectively, so as to accurately judge whether the modulator is at the optimal operating point.

[0081] In some embodiments, the above step S103, adjusting the operating parameter based on the first adjustment amount to obtain the target operating parameter, may include the following steps S141 to S143:

[0082] Step S141: adjusting the operating parameter based on the first adjustment amount to obtain a first operating parameter;

[0083] In some implementations, when the working parameter includes input optical power, the first adjustment amount includes an input optical power adjustment amount, and the input optical power is adjusted according to the input optical power adjustment amount to obtain the first input optical power.

[0084] In some implementations, when the operating parameter includes a bias voltage, the first adjustment amount includes a bias voltage adjustment amount, and the bias voltage is adjusted according to the bias voltage adjustment amount to obtain the first bias voltage.

[0085] Step S142: modulating the signal to be modulated based on the first working parameter to obtain a second modulated signal;

[0086] In some implementations, when the working parameters include input optical power, the first input optical power is used as the optical power of the input signal of the modulator, and the input signal to be modulated is modulated to obtain a second modulated signal.

[0087] In some implementations, when the operating parameters include a bias voltage, the first bias voltage is used as a bias voltage of the modulator to modulate the input signal to be modulated to obtain a second modulated signal.

[0088] Step S143: measuring a scattering parameter corresponding to the second modulation signal to obtain a second measurement value of the scattering parameter, and determining the first operating parameter as a target operating parameter when the second measurement value satisfies the modulation condition.

[0089] In some implementations, when the second measured value does not satisfy the modulation condition, a second adjustment amount is determined based on the second measured value to continue adjusting the operating parameter until the measured value satisfies the modulation condition.

[0090] In the embodiment of the present application, the working parameter is adjusted according to the first adjustment amount to obtain the first working parameter; the signal to be modulated is modulated according to the first working parameter to obtain the second modulated signal; the scattering parameter corresponding to the second modulated signal is measured to obtain the second measured value of the scattering parameter, and when the second measured value meets the modulation condition, the first working parameter is determined as the target working parameter. In this way, the first working parameter corresponding to the second measured value meeting the modulation condition is used as the target working parameter, so that the signal modulation circuit performs signal modulation under the target working parameter, thereby improving the efficiency and accuracy of signal modulation.

[0091] In some embodiments, the above method further includes the following steps S151 and S152:

[0092] Step S151: determining a second adjustment amount of the operating parameter based on the second measurement value of the scattering parameter when the second measurement value does not satisfy the modulation condition;

[0093] Step S152: Based on the second adjustment amount, the first operating parameter is adjusted to obtain a target operating parameter.

[0094] In some embodiments, during the signal modulation process, the scattering parameters corresponding to the modulated signal output by the modulator are measured in real time to determine whether the modulation conditions are met. If the modulation conditions are not met, the operating parameters are iteratively adjusted multiple times based on the measured values ​​of the scattering parameters until the measured values ​​meet the modulation conditions.

[0095] In the embodiment of the present application, when the second measured value does not meet the modulation condition, the second adjustment amount of the working parameter is determined based on the second measured value of the scattering parameter, and the working parameter is adjusted according to the second adjustment amount to obtain the target working parameter. In this way, when the second measured value does not meet the modulation condition, the adjustment amount of the first working parameter is calculated, and the first working parameter is continuously adjusted until the target working parameter is obtained, so that the signal modulation circuit performs signal modulation under the target working parameter, thereby improving the efficiency and accuracy of signal modulation.

[0096] In some embodiments, the operating parameters include input optical power and bias voltage; the above step S103 of adjusting the operating parameters based on the first adjustment amount to obtain target operating parameters may include the following step S161:

[0097] Step S161: Based on the first adjustment amount, the input optical power and / or the bias voltage is adjusted to obtain a target input optical power and / or a target bias voltage.

[0098] In some implementations, when the working parameter includes input optical power, the first adjustment amount includes an input optical power adjustment amount, and the input optical power is adjusted according to the input optical power adjustment amount to obtain a target input optical power.

[0099] In some implementations, when the operating parameter includes a bias voltage, the first adjustment amount includes a bias voltage adjustment amount, and the bias voltage is adjusted according to the bias voltage adjustment amount to obtain a target bias voltage.

[0100] In an embodiment of the present application, the input optical power and / or bias voltage are adjusted according to the first adjustment amount to obtain the target input optical power and / or target bias voltage, so that the signal modulation circuit utilizes the target input optical power and / or target bias voltage to modulate the signal, thereby improving the efficiency of signal modulation.

[0101] In some embodiments, the measuring of the scattering parameter corresponding to the first modulated signal in step S102 to obtain the first measured value of the scattering parameter may include the following step S171:

[0102] Step S171: after converting the first modulated signal from an optical signal to an electrical signal, measuring a scattering parameter corresponding to the first modulated signal to obtain a first measured value of the scattering parameter.

[0103] In some embodiments, the signal modulation circuit further includes a photodetector, and before measuring the scattering parameter corresponding to the first modulation signal, the photodetector is used to convert the first modulation signal from an optical signal to an electrical signal.

[0104] The embodiment of the present application provides a signal modulation circuit. Figure 2 A schematic diagram of the structure of a signal modulation circuit provided in an embodiment of the present application is shown in FIG. Figure 2 As shown, the signal modulation circuit 200 includes a modulator 201, a vector network analyzer 202, a controller 203 and a driving circuit 204, wherein:

[0105] The modulator 201 is used to modulate the signal to be modulated obtained from the light source to obtain a first modulated signal;

[0106] The vector network analyzer 202 is used to measure the scattering parameter corresponding to the first modulated signal to obtain a first measured value of the scattering parameter;

[0107] The controller 203 is used to determine a first adjustment amount corresponding to an operating parameter of the signal modulation circuit based on a first measurement value of the scattering parameter when the first measurement value does not meet the modulation condition; the scattering parameter is used to describe a transmission characteristic and / or a reflection characteristic between the signal to be modulated and the first modulated signal;

[0108] The driving circuit 204 is used to adjust the operating parameter based on the first adjustment amount to obtain a target operating parameter;

[0109] The modulator 201 is further configured to modulate the signal to be modulated based on the target operating parameter.

[0110] In the embodiment of the present application, the modulator modulates the signal to be modulated to obtain a first modulated signal; the vector network analyzer measures the scattering parameter corresponding to the first modulated signal to obtain a first measurement value; the controller determines the adjustment amount corresponding to the working parameter of the signal modulation circuit according to the first measurement value when the first measurement value does not meet the modulation condition; the driving circuit adjusts the working parameter according to the adjustment amount; the modulator modulates the signal to be modulated according to the target working parameter obtained after the adjustment. In this way, when the measured value of the scattering parameter does not meet the modulation condition, the working parameter is adjusted to obtain the target working parameter, so that the signal modulation circuit modulates the signal to be modulated under the target working parameter, thereby improving the efficiency and accuracy of signal modulation.

[0111] In some embodiments, the first measurement value includes an amplitude measurement value, a phase measurement value, and a reflection measurement value; and the vector network analyzer is further configured to:

[0112] Based on the amplitude of the signal to be modulated and the amplitude of the first modulated signal, determine the amplitude measurement value of the scattering parameter; based on the phase of the signal to be modulated and the phase of the first modulated signal, determine the phase measurement value of the scattering parameter; based on the signal to be modulated and the reflected signal corresponding to the signal to be modulated, determine the reflection measurement value of the scattering parameter.

[0113] The controller is further configured to determine a first adjustment amount of the operating parameter based on the amplitude measurement value, the phase measurement value and / or the reflection measurement value.

[0114] In some embodiments, the controller is further used to determine that the first measurement value does not satisfy the modulation condition when the modulator has not reached an optimal operating point; the modulation efficiency of the modulator is highest when it reaches the optimal operating point.

[0115] In some embodiments, the scattering parameters include amplitude parameters, phase parameters and reflection parameters; the controller is also used for at least one of the following: when the amplitude measurement value corresponding to the amplitude parameter is less than the amplitude reference value, determining that the modulator has not reached the optimal operating point; when the phase measurement value corresponding to the phase parameter and the phase reference value do not satisfy a linear relationship, determining that the modulator has not reached the optimal operating point; when the reflection measurement value corresponding to the reflection parameter is greater than the reflection reference value, determining that the modulator has not reached the optimal operating point.

[0116] In some embodiments, the driving circuit is further used to adjust the operating parameter based on the first adjustment amount to obtain a first operating parameter;

[0117] The modulator is further configured to modulate the signal to be modulated based on the first operating parameter to obtain a second modulated signal;

[0118] The vector network analyzer is further used to measure a scattering parameter corresponding to the second modulated signal to obtain a second measured value of the scattering parameter.

[0119] The driving circuit is further configured to determine the first operating parameter as a target operating parameter when the second measurement value satisfies the modulation condition.

[0120] In some embodiments, the controller is further configured to determine a second adjustment amount of the operating parameter based on the second measurement value of the scattering parameter when the second measurement value does not satisfy the modulation condition;

[0121] The driving circuit is further used to adjust the first operating parameter based on the second adjustment amount to obtain a target operating parameter.

[0122] In some embodiments, the driving circuit is further configured to adjust the input optical power and / or the bias voltage based on the first adjustment amount.

[0123] In some embodiments, the signal modulation circuit further includes a photodetector, and the photodetector is used to measure a scattering parameter corresponding to the first modulation signal after converting the first modulation signal from an optical signal to an electrical signal to obtain a first measurement value of the scattering parameter.

[0124] The following describes the application of the embodiments of the present application in actual scenarios.

[0125] In the related art, there are two methods for automatically controlling the working point of the modulator. The first method is to realize closed-loop control based on average optical power detection. This method cannot fully reflect the working state of the modulator, such as phase change, frequency response, etc., and in some cases, even if the optical power remains stable, the phase of the modulator may drift, resulting in signal distortion. In addition, the performance of the modulator is affected by environmental factors such as temperature, humidity, vibration, etc., resulting in unstable bias point control. The second method is to use the disturbance detection method to realize closed-loop control. This method is to introduce a disturbance signal from the bias pin of the modulator. In high-speed optical communication systems, weak signal interference may also cause distortion or additional noise in the optical signal, affecting system performance and increasing the bit error rate. In addition, for some special modulation formats or extreme working conditions, the disturbance detection method cannot find a suitable disturbance signal to accurately adjust the bias working point to the optimal working point, which limits the application range and performance of the modulator. And in an environment with large temperature changes, changes in the response characteristics of the optical detector may cause inaccurate measurement of the disturbance signal, thereby affecting the control accuracy of the bias point.

[0126] Based on the above description, an embodiment of the present application provides a method for closed-loop automatic control to adjust the optimal operating point of a silicon optical modulator. By measuring the scattering parameters (S parameters) of the output signal of the modulator, it is determined whether the modulator has reached the optimal operating point. If the optimal operating point has not been reached, the adjustment amount is calculated, and parameters such as input optical power and bias voltage are adjusted according to the adjustment amount.

[0127] S parameters are parameters that describe the characteristics of a linear two-port network. For a Mach-Zehnder modulator (MZM), S parameters can reflect the amplitude and phase relationship between its input and output optical signals. The specific functions are as follows:

[0128] (1) The S21 amplitude reflects the change in the intensity of the optical signal transmitted from the input port to the output port of the MZM. At the optimal working point, the interference effect inside the MZM reaches the optimal level, making the modulation efficiency of the optical signal the highest. The S21 amplitude is large, and this amplitude should be relatively stable within a certain frequency range without large fluctuations. Therefore, the larger the S21 amplitude, the higher the power transmission efficiency of the optical signal from the input port to the output port, that is, the smaller the signal loss.

[0129] (2) The S21 phase reflects the phase change of the optical signal from the input port to the output port of the MZM. Near the optimal operating point, the phase change of S21 is relatively linear. This is because the MZM achieves modulation by changing the optical path difference between the two interference arms, and at the optimal operating point, there is a good linear relationship between the change in the optical path difference and the driving signal (such as bias voltage) applied by the driving circuit. For coherent optical communication systems, linear phase changes can ensure accurate transmission of the phase information of the signal during the modulation process and reduce signal distortion.

[0130] (3) The S11 parameter represents the reflection coefficient of the input port. Although the S11 parameter is not the main parameter for directly determining the optimal operating point, it can assist in determining the matching between the MZM and the input light source. If the S11 is large, it means that the input optical signal has more reflections, which may affect the normal operation of the MZM and cause the MZM's operating point to shift. Ideally, the S11 should be as small as possible to ensure that the input optical signal can effectively enter the MZM for modulation.

[0131] In the embodiment of the present application, Figure 3 A schematic diagram of a signal modulation system for automatically controlling and adjusting the optimal operating point of a silicon optical modulator provided in an embodiment of the present application is shown in FIG. Figure 3 As shown, it includes a light source 205, a modulator 201, a light detector 206, a vector network analyzer 202, a controller 203, and a driving circuit 204.

[0132] In the embodiment of the present application, using the above signal modulation system to automatically control and adjust the optimal working point of the silicon light modulator may include the following steps S301 to S306:

[0133] Step S301: The stable light source 205 sends an optical signal to the modulator 201, and the modulator 201 modulates the input optical signal and outputs a modulated signal;

[0134] Step S302: the optical detector 206 converts the output modulated signal from an optical signal into an electrical signal;

[0135] Step S303: the vector network analyzer 202 (VNA) measures the S parameters corresponding to the modulated signal output by the modulator in real time, and sends the S parameters to the controller 203;

[0136] Step S304: the controller 203 analyzes the S parameter to determine whether the modulator 201 is at the optimal operating point; if so, the control of the optimal operating point of the modulator 201 is completed; if not, the adjustment amount is calculated and sent to the driving circuit 204, and the process proceeds to step S305;

[0137] Based on the measured S parameters and the reference values ​​corresponding to the S parameters, it is determined whether the modulator is at the optimal operating point.

[0138] The reference value of the S parameter when the modulator is at the optimal operating point needs to be determined through theoretical analysis, simulation or experimental calibration. For S21 amplitude, it is the maximum stable amplitude value under a specific input optical power and modulation frequency. For S21 phase, it is the linear phase change range under the same conditions. These reference values ​​are stored in the controller's memory as a standard for determining whether the modulator is at the optimal operating point.

[0139] During the signal modulation process, the vector network analyzer measures the S parameters of the modulator's output optical signal in real time. The controller compares the received amplitude and phase information of the S21 parameter with the stored reference standard. For the S21 amplitude, if the actual measured value is lower than the reference value or there is a large fluctuation, it means that the modulator may not be at the optimal operating point. For the S21 phase, if its change deviates from the linear characteristic, it also indicates that the modulator is not at the optimal operating point, real-time monitoring and comparison.

[0140] Step S305: the driving circuit 204 adjusts the bias voltage, input optical power and other parameters of the modulator 201 according to the adjustment amount, so that the working point of the modulator 201 gradually approaches the optimal working point;

[0141] Step S306: Repeat the above steps S301 to S305 to form a closed-loop automatic control until the modulator 201 reaches the optimal operating point.

[0142] In the embodiment of the present application, during the signal modulation process, the S parameters of the modulator output signal are measured in real time, and the S parameters are analyzed to determine whether the modulator is at the optimal working point; when it is determined that the modulator is not at the optimal working point, the adjustment amount is calculated, and the input optical power and bias voltage are adjusted according to the adjustment amount, so as to realize automatic control of the working point of the modulator, improve the efficiency and accuracy of signal modulation, and make the modulator at the optimal working point. Moreover, this method can be adjusted and optimized according to different modulators and application scenarios, and has strong adaptability.

[0143] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in various embodiments of the present application, the size of the serial number of each step / process mentioned above does not mean the order of execution, and the execution order of each step / process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application. The serial numbers of the embodiments of the present application mentioned above are for description only and do not represent the advantages and disadvantages of the embodiments.

[0144] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0145] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0146] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units; they may be located in one place or distributed on multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0147] In addition, all functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may be a separate unit, or two or more units may be integrated into one unit; the above-mentioned integrated units may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0148] A person skilled in the art can understand that all or part of the steps of implementing the above method embodiment can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps of the above method embodiment; and the aforementioned storage medium includes: mobile storage devices, read-only memories (ROM), magnetic disks or optical disks, etc., various media that can store program codes.

[0149] Alternatively, if the above-mentioned integrated unit of the present application is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can essentially or in other words, the part that contributes to the relevant technology can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROMs, magnetic disks, or optical disks.

[0150] The above is only an implementation method of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A signal modulation method, characterized in that: Applied to a signal modulation circuit, the method comprises: Modulating the signal to be modulated obtained from the light source to obtain a first modulated signal; Measuring a scattering parameter corresponding to the first modulation signal to obtain a first measurement value of the scattering parameter; and determining a first adjustment amount corresponding to an operating parameter of the signal modulation circuit based on the first measurement value of the scattering parameter when the first measurement value does not meet a modulation condition; the scattering parameter is used to describe a transmission characteristic and / or a reflection characteristic between the signal to be modulated and the first modulation signal; Based on the first adjustment amount, adjusting the operating parameter to obtain a target operating parameter; The signal to be modulated is modulated based on the target operating parameter.

2. The method according to claim 1, characterized in that The first measurement value includes an amplitude measurement value, a phase measurement value, and a reflection measurement value; and the step of measuring the scattering parameter corresponding to the first modulated signal to obtain the first measurement value of the scattering parameter includes at least one of the following: Determining an amplitude measurement value of the scattering parameter based on the amplitude of the signal to be modulated and the amplitude of the first modulated signal; Determining a phase measurement value of the scattering parameter based on the phase of the signal to be modulated and the phase of the first modulated signal; Determining a reflection measurement value of the scattering parameter based on the signal to be modulated and a reflection signal corresponding to the signal to be modulated; The determining, based on the first measured value of the scattering parameter, a first adjustment amount corresponding to the operating parameter of the signal modulation circuit includes: A first adjustment to the operating parameter is determined based on the amplitude measurement, the phase measurement, and / or the reflection measurement.

3. The method according to claim 1, characterized in that The signal modulation circuit includes a modulator, and the method further includes: When the modulator does not reach the optimal operating point, it is determined that the first measurement value does not satisfy the modulation condition; the modulation efficiency of the modulator is highest when the modulator reaches the optimal operating point.

4. The method according to claim 3, characterized in that The scattering parameters include amplitude parameters, phase parameters and reflection parameters; the method further includes at least one of the following: When the amplitude measurement value corresponding to the amplitude parameter is less than the amplitude reference value, determining that the modulator has not reached the optimal operating point; In the case that a linear relationship is not satisfied between a phase measurement value corresponding to the phase parameter and a phase reference value, determining that the modulator has not reached an optimal operating point; When the reflection measurement value corresponding to the reflection parameter is greater than the reflection reference value, it is determined that the modulator has not reached the optimal working point.

5. The method according to any one of claims 1 to 4, characterized in that The adjusting the operating parameter based on the first adjustment amount to obtain a target operating parameter includes: Based on the first adjustment amount, adjusting the operating parameter to obtain a first operating parameter; Based on the first operating parameter, modulate the signal to be modulated to obtain a second modulated signal; A scattering parameter corresponding to the second modulation signal is measured to obtain a second measurement value of the scattering parameter, and when the second measurement value satisfies the modulation condition, the first operating parameter is determined as a target operating parameter.

6. The method according to claim 5, characterized in that The method further comprises: In a case where the second measurement value does not satisfy the modulation condition, determining a second adjustment amount of the operating parameter based on the second measurement value of the scattering parameter; Based on the second adjustment amount, the first operating parameter is adjusted to obtain a target operating parameter.

7. The method according to any one of claims 1 to 4, characterized in that The operating parameters include input optical power and bias voltage; and adjusting the operating parameters based on the first adjustment amount to obtain target operating parameters includes: Based on the first adjustment amount, the input optical power and / or the bias voltage are adjusted to obtain a target input optical power and / or a target bias voltage.

8. The method according to any one of claims 1 to 4, characterized in that The measuring the scattering parameter corresponding to the first modulated signal to obtain a first measurement value of the scattering parameter includes: After converting the first modulated signal from an optical signal to an electrical signal, a scattering parameter corresponding to the first modulated signal is measured to obtain a first measured value of the scattering parameter.

9. A signal modulation circuit, characterized in that: It includes a modulator, a vector network analyzer, a controller and a driving circuit, wherein: The modulator is used to modulate the signal to be modulated obtained from the light source to obtain a first modulated signal; The vector network analyzer is used to measure a scattering parameter corresponding to the first modulated signal to obtain a first measured value of the scattering parameter; The controller is configured to determine, when the first measurement value does not satisfy the modulation condition, a first adjustment amount corresponding to the working parameter of the signal modulation circuit based on the first measurement value of the scattering parameter; the scattering parameter is used to describe the transmission characteristics and / or reflection characteristics between the signal to be modulated and the first modulation signal; The driving circuit is used to adjust the operating parameter based on the first adjustment amount to obtain a target operating parameter; The modulator is further used to modulate the signal to be modulated based on the target operating parameter.

10. A chip, characterized in that: Comprising a signal modulation circuit as claimed in claim 9.

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