A device and method for compensating polarization loss in high-speed electro-optic response measurement

Abstract

The application belongs to the technical field of polarization loss compensation, and particularly relates to a polarization loss compensation device and method in high-speed electro-optical response measurement. The device adopts PBS light splitting, one way of which is input to a broadband photodetector, and the other way is input to a photodetector and subjected to I / V conversion. By monitoring the ratio of the current value of the broadband photodetector to the I / V conversion value, the effect of differential amplification maximization can be achieved, and the method has higher detection sensitivity. The application monitors the input light, can overcome the polarization misjudgment caused by the power fluctuation of the input light signal, combines the power value fluctuation for compensation, and can ensure more accurate electro-optical signal polarization state adjustment and improve tracking accuracy.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polarization loss compensation, and particularly relates to a polarization loss compensation method in high-speed electro-optical response measurement. BACKGROUND

[0002] With the increasing rate of current high-speed modulated optical wave signals, optical polarization-sensitive devices also appear in coherent modulation optical receiving units. The optical amplitude modulation signals at high speed are interfered by the signals themselves when received, leading to an increase in error codes, including link loss fluctuation, dispersion, polarization, etc. The high-speed photoelectric devices are affected by the polarization-related loss of high-speed photoelectric detection units, mainly because the high-speed photoelectric devices have different responses to high-speed optical wave signals with different input polarization states, which further affects the detection sensitivity of high-speed photoelectric receiving units. The polarization-related loss of general high-speed photoelectric detection units can be as high as 0.2dB-0.4dB, and the polarization-related loss in the link can be as high as 2dB (the highest value required by the communication standard). The high-speed photoelectric conversion unit, as a key core receiving component, needs to be considered in the design of signal conversion efficiency and accuracy, especially when used for small signal measurement of optical instruments. The receiving linearity range of the signal can be as high as 20dB, and the minimum signal detection sensitivity can be as low as-10dBm or below. When used for accessing the measured device, the measurement error caused by the polarization-related loss can reach 0.4-0.8dB, which will seriously affect the measurement accuracy. In the development of optical receivers, the minimum detection sensitivity can be as low as-12dBm or below, and the power fluctuation caused by the polarization of the high-speed photoelectric detection unit can be as high as 0.4dB or above. The polarization-related loss introduced by the detection unit is unacceptable.

[0003] There is no response scheme for the polarization-related loss in the high-speed photoelectric conversion unit. The current compensation is mainly for the compensation scheme of high-speed optical fiber communication link. With the increasing requirement of high-speed photoelectric detection response rate, the response of the detection unit to the electro-optical signal is more and more affected by the polarization-related loss of the detection unit itself. How to compensate or eliminate the polarization-related loss can improve the sensitivity and test repeatability of the high-speed photoelectric detection unit.

[0004] For the polarization dependent loss method of the optical fiber link, generally, the so-called "blind algorithm" is usually used to approximately estimate the original signal, and the Jones matrix (the device under the premise of no any loss change) is used to establish the signal attenuation effect model of each receiving channel. The channel model of the polarization dependent loss can use the representation method of the Jones matrix. By using these estimation methods, it is not required to understand the original signal (except for the modulation mode), and a series of equalization filters are used to filter the received signal to obtain the inverse of the Jones matrix. The algorithm iteratively searches for the filter variable group (alpha, beta, k...), and finally obtains the convergence result, which means that the measured symbol is mapped to the symbol calculated by the algorithm with the minimum error. The disadvantage of this method is that the same polarization channel may be recovered twice. This problem is called the singularity of the algorithm. This method is also very complex because each symbol must be processed individually to calculate the next iteration step. The algorithm only estimates the polarization loss model of the probe receiving front end, and cannot compensate for the polarization loss of the probe receiving unit itself.

[0005] The technical problems to be solved by the present application are: (1) how to overcome the power fluctuation problem caused by the optical polarization loss of the high-speed photoelectric conversion unit; (2) how to compensate for the polarization loss of the high-speed photoelectric conversion unit in an online manner. SUMMARY

[0006] In order to improve the sensitivity of the photoelectric conversion receiving unit, the present application provides a polarization loss compensation method in high-speed electro-optic response measurement. The method can realize polarization-independent characteristics of the high-speed photoelectric conversion unit in the receiving signal unit. The method can realize high-speed photoelectric conversion in real time, solve the signal conversion precision problem caused by polarization in the input signal link, improve the power consistency of the photoelectric receiving unit, and improve the measurement accuracy.

[0007] The present application is realized by the following technical solutions:

[0008] A polarization loss compensation device in high-speed electro-optic response measurement, the device comprises:

[0009] A beam splitter is used to receive the measured electro-optic modulation signal and split the electro-optic modulation signal. Part of the split electro-optic modulation signal is transmitted to a fiber polarization controller, and the other part is transmitted to a second photoelectric detector. The second photoelectric detector is connected to a power monitoring unit. Specifically, the power monitoring unit uses an optical power meter.

[0010] A fiber polarization controller is connected to the optical beam splitter and is used to receive the electro-optic modulation signal and control the polarization state of the electro-optic modulation signal.

[0011] A high-speed drive circuit is connected to the fiber polarization controller and is used to drive the fiber polarization controller to realize high-speed adjustment of the fiber polarization state.

[0012] a polarization beam splitter connected to the optical fiber polarization controller, the polarization beam splitter receiving the optical signal output by the optical fiber polarization controller and outputting two paths of orthogonal polarization state light;

[0013] a broadband high-speed photodetector, which is a compensation object and is connected to the polarization beam splitter and receives one path of polarization state light from the polarization beam splitter;

[0014] A first photodetector is connected to the polarization beam splitter to receive the other polarized light from the polarization beam splitter; the first photodetector is connected to a current-to-voltage converter; the first photodetector performs photocurrent detection on the polarized light and then converts the current-to-voltage converter into a first voltage signal;

[0015] A precision current monitoring unit, connected to the broadband high-speed photodetector, for monitoring the photocurrent and outputting a second voltage signal;

[0016] a divider connected to the precision current monitoring unit and the current-voltage converter, and dividing the second voltage signal and the first voltage signal to obtain a current polarization state result;

[0017] The controller is connected to the divider, the high-speed driving circuit and the power monitoring unit.

[0018] Furthermore, the beam splitter is a 1:99 beam splitter.

[0019] Furthermore, the optical fiber polarization controller adopts a lithium niobate polarization controller.

[0020] A method for compensating for polarization loss in high-speed electro-optical response measurement, the method comprising:

[0021] (1) performing polarization loss calibration on a broadband high-speed photodetector under conditions of a certain optical input power and different wavelengths, obtaining polarization state results corresponding to different wavelengths during the calibration phase, and storing the polarization state results;

[0022] (2) After receiving the current target test optical signal, the controller will s , query the polarization state result SD of the corresponding wavelength stored during the calibration phase s ; The polarization state result SD s As the target value tracked during monitoring;

[0023] (3) The controller starts the power monitoring unit to monitor the power of the current target test optical signal, obtains the current power value P2, compares the current power value P2 with the initial power P of the current target test optical signal, and obtains the power fluctuation ΔP of the current target test optical signal, ΔP=P2-P;

[0024] Calculate the actual tracking target value SD s 'for:

[0025] SD s '=((V PD＝s+ ΔV PD ) / (V PD1＝s+ ΔV PD1 ))*(1-(ΔP / P)*K);

[0026] Among them, V PD＝s V is the second voltage signal output by the precision current monitoring unit before the power fluctuation ΔP occurs. PD1＝s ΔV is the first voltage signal output by the current-voltage converter before the power fluctuation ΔP occurs; PD The voltage compensation output by the precision current monitoring unit after power fluctuation ΔP occurs; ΔV PD1 is the output voltage compensation of the current-to-voltage converter after the power fluctuation ΔP occurs; K is the linear response factor mapped from the power monitoring unit to the voltage signal;

[0027] (4) The controller calculates the actual tracking target value SD s 'With target value SD s Error|SD s '-SD s |, when |SD s '-SD s |Greater than the threshold SD Th When , the controller drives the fiber polarization controller to adjust the state once;

[0028] (5) Repeat steps (3) to (4) until |SD s '-SD s The error signal of | satisfies |SD s '-SD s |Less than the threshold SD Th .

[0029] Furthermore, step (1) is specifically as follows:

[0030] 1) The tunable laser source is controlled by an external computer to achieve accurate setting of the target wavelength range. The calibration wavelengths of the tunable source are set to λ1, λ2, ..., λ i ,…,λ n , set the initial power of the tunable source wavelength to P;

[0031] 2) When the calibration wavelength output by the tunable laser source is λ i , the computer sends a command to the controller, the controller acquires the optical power P2 measured by the power monitoring unit, and the controller controls the high-speed drive circuit to adjust the polarization state of the input electrical signal by the fiber polarization controller;

[0032] The controller synchronously acquires the first voltage signal V PD1_i output by the current-voltage converter and the second voltage signal V PD_i output by the precision current detection unit; the two voltage signals are divided to obtain the current polarization state result SD i :

[0033] SD i = V PD_i / V PD1_i ;

[0034] When the current wavelength λ i is recorded, the polarization state result SD i corresponding to the power P2 is stored in the table; after the controller completes the storage, the high-speed drive circuit is adjusted to adjust the polarization state of the fiber polarization controller, and a series of polarization state results SD0, SD1, …, SDn are obtained; the maximum value SD Max is recorded.

[0035] 3) The computer changes the wavelength λ of the tunable source in sequence, repeats step 2), records the maximum value SD Max corresponding to each wavelength and stores it; and the calibration is completed

[0036] The beneficial technical effects of the present application are as follows:

[0037] The polarization loss compensation device for high-speed electro-optical response measurement provided by the present application adopts PBS splitting, one path is input to a broadband high-speed photodetector, and the other path is input to a first photodetector and is subjected to I / V conversion; by monitoring the ratio of the current value of the high-speed photodetector to the I / V conversion value, the effect of maximum differential amplification can be achieved, and the detection sensitivity is higher.

[0038] The polarization loss compensation device for high-speed electro-optical response measurement provided by the present application monitors the input light by using a power monitoring unit, which can overcome the polarization misjudgment caused by the power fluctuation of the input light signal, and can ensure more accurate electro-optical signal polarization state adjustment and improve tracking accuracy by combining the monitoring power value fluctuation and compensation.

[0039] The polarization loss compensation method for high-speed electro-optical response measurement provided by the application adopts wavelength polarization correlation loss pre-calibration, selects appropriate differential amplification values SDi according to actual working wavelengths, and provides response measurement under different wavelengths, so that the response compensation of high-speed photoelectric detectors under different wavelengths is solved, and the application range is wider.

[0040] The application adopts conventional fiber optics to build, does not need complex algorithm development, is easy to implement, has fast control speed, and has relatively low cost. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 A high-speed electro-optical response measurement polarization loss compensation device in an embodiment of the application is shown in the figure;

[0042] Figure 2 A pre-calibration diagram of the high-speed electro-optical response measurement polarization loss compensation device in an embodiment of the application is shown in the figure;

[0043] Figure 3 A polarization state result SD in pre-calibration in an embodiment of the application is shown in the figure; i Conversion relationship. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the application clearer and more comprehensible, the application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and do not limit the application.

[0045] On the contrary, the application covers any substitution, modification, equivalent method and scheme made on the essence and scope of the application as defined by the claims. Further, in order to make the public have a better understanding of the application, some specific details are described in detail in the following detailed description of the application. The application can also be completely understood without the description of these details by those skilled in the art.

[0046] Embodiment 1: A high-speed electro-optical response measurement polarization loss compensation device, as shown in the figure, the device comprises: Figure 1

[0047] A beam splitter is used to receive an electro-optical modulation signal to be measured and split the electro-optical modulation signal, part of the split electro-optical modulation signal is transmitted to a fiber polarization controller, and the other part is transmitted to a second photoelectric detector, the second photoelectric detector is connected with a power monitoring unit; specifically, the power monitoring unit adopts an optical power meter;

[0048] A fiber polarization controller is connected with the optical beam splitter; used to receive an electro-optical modulation signal and control the polarization state of the electro-optical modulation signal;

[0049] ​a high-speed driving circuit connected with the fiber polarization controller, for driving the fiber polarization controller to realize high-speed adjustment of the fiber polarization state;

[0050] a polarization beam splitter connected with the fiber polarization controller, the polarization beam splitter receiving the optical signal output by the fiber polarization controller and outputting two paths of orthogonal polarization state light;

[0051] a broadband high-speed photodetector, which is a compensation object, connected with the polarization beam splitter and receiving one path of polarization state light from the polarization beam splitter;

[0052] a first photodetector connected with the polarization beam splitter and receiving the other path of polarization state light from the polarization beam splitter; the first photodetector is connected with a current-voltage converter; the first photodetector converts the polarization state light into a first voltage signal after current-voltage conversion by the current-voltage converter;

[0053] a precision current monitoring unit connected with the broadband high-speed photodetector, for realizing monitoring of the photocurrent and outputting a second voltage signal;

[0054] a divider connected with the precision current monitoring unit and the current-voltage converter, for obtaining a current polarization state result by dividing the second voltage signal and the first voltage signal;

[0055] a controller connected with the divider, the high-speed driving circuit and the power monitoring unit.

[0056] After data acquisition of the divider by the controller, feedback is given to the high-speed driving circuit, and the fiber polarization state in the optical link is adjusted by the circuit, so that the polarization light input to the broadband high-speed photodetector remains unchanged. This process requires that the direction of the maximum response polarization state of the broadband high-speed response photodetector (i.e. the broadband high-speed photodetector) is consistent with the optical axis direction of the light input to the high-speed response photodetector after PBS splitting, so as to ensure that the maximum response value of the detector is used as an extreme value tracking feature target point.

[0057] In this embodiment, the beam splitter is a 1:99 beam splitter. Specifically, after the input electro-optical modulation signal passes through the 1:99 single-mode optical beam splitter, 99% of the input is input to the fiber polarization controller, and 1% of the input is input to the photodetector 2 as an average power meter for monitoring the current power intensity.

[0058] In this embodiment, the fiber polarization controller adopts a lithium niobate polarization controller, which has the advantage of fast adjustment speed.

[0059] In the embodiment, the broadband high-speed photodetector is distinguished from the first photodetector and the second photodetector, the broadband high-speed photodetector can realize demodulation of light amplitude intensity, restore high-speed modulated light signal, and requires that the direction of the maximum response polarization state of the broadband high-speed photodetector is consistent with the direction of the optical axis of the light input into the broadband high-speed photodetector after the PBS splits, so as to ensure that the maximum response value of the photodetector is an extreme value tracking feature target point.

[0060] Embodiment 2: A polarization loss compensation method in high-speed electro-optical response measurement, using the device of embodiment 1, the method comprises:

[0061] (1) Calibrate the polarization loss of the broadband high-speed photodetector under certain light input power and different wavelengths, obtain the polarization state results corresponding to different wavelengths in the calibration stage, and store the polarization state results;

[0062] (2) After receiving the current target test light signal, the controller queries the polarization state results SD s corresponding to the wavelength of the current target test light signal λ s stored in the calibration stage according to the wavelength λ s of the current target test light signal, and takes the polarization state results SD s as the target value tracked at the monitoring time;

[0063] (3) The controller starts the power monitoring unit to monitor the power of the current target test light signal, obtains the current power value P2, compares the current power value P2 with the initial power P of the current target test light signal, obtains the power fluctuation ΔP of the current target test light signal, ΔP=P2-P;

[0064] The actual tracked target value SD s ' is calculated as:

[0065] SD PD＝s+ '=((V PD ΔV PD1＝s+ ) / (V PD1 ΔV PD＝s ))*(1-(ΔP / P)*K);

[0066] Wherein, V PD1＝s is the second voltage signal output by the precision current monitoring unit before the power fluctuation ΔP occurs, V PD is the first voltage signal output by the current-voltage converter before the power fluctuation ΔP occurs; ΔV PD1 is the voltage compensation output by the precision current monitoring unit after the power fluctuation ΔP occurs.The output voltage compensation of the current-to-voltage converter after a power fluctuation ΔP occurs; P is the power of the current target test optical signal, and K is the linear response factor of the optical power monitoring unit mapped to the voltage signal (this factor is calculated based on the detector responsivity and circuit amplification factor, and is a conventional technology);

[0067] Among them, the optical power monitoring unit plays two important roles. One is to judge the current input of the electro-optical signal and whether there is an optical signal input. If so, the controller will automatically start the SD s Tracking process, if not, wait until there is an input signal to monitor and then track; secondly, when there is an optical signal input, the power of the input optical signal will fluctuate ΔP to a certain extent, which will cause the back-end to monitor SD s Misjudgment during tracking. This misjudgment is not caused by the polarization state of the input signal, but by the input optical power itself. By monitoring the change in optical power ΔP, the corresponding I / V conversion output voltage is compensated to ΔV PD , the voltage compensation generated by the precision current monitoring unit is ΔV PD1 .

[0068] (4) The controller calculates the actual tracking target value SD s 'With target value SD s Error|SD s '-SD s |, when |SD s '-SD s |Greater than the threshold SD Th When , the controller drives the fiber polarization controller to adjust the state once;

[0069] (5) Repeat steps (3) to (4) until |SD s '-SD s The error signal of | satisfies |SD s '-SD s |Less than the threshold SD Th ; To avoid polarization misjudgment caused by fluctuations in the input optical signal power.

[0070] Among them, the threshold SD Th It is set according to the polarization-dependent loss characteristics of the detector itself and the requirements for test response accuracy and repeatability.

[0071] The compensation method provided by the present invention enables real-time polarization state control of the input optical signal when the high-speed electro-optical signal under test is input into the compensation device, ensuring that the polarization state of the input optical signal connected to the broadband high-speed photodetector remains consistent with the calibration state. Regardless of how the polarization direction of the input signal changes, the polarization state direction of the current maximum detector response is determined by measuring the current information of the photodetector and the voltage ratio of the I / V conversion of the other signal after PBS splitting. The optical fiber polarization controller is constantly adjusted by the controller to track the polarization state.

[0072] In this embodiment, since the polarization-dependent loss of the broadband high-speed response photodetector in each device is different in magnitude and the polarization-dependent loss angle is different, and the input wavelength is also affected differently, it is necessary to calibrate the polarization-dependent parameters when applying this method, and it is necessary to pre-calibrate the polarization-dependent loss of the photodetector; for example, Figure 2 As shown, step (1) is specifically as follows:

[0073] 1) The tunable laser source is controlled by an external computer to achieve accurate setting of the target wavelength range. The calibration wavelengths of the tunable source are set to λ1, λ2, ..., λ i ,…,λ n , set the initial power of the tunable source wavelength to P;

[0074] 2) When the calibrated wavelength of the tunable laser source output is λ i When the optical power P2 is measured by the power monitoring unit, the computer sends a command to the controller, and the controller controls the high-speed driving circuit to adjust the polarization state of the input electrical signal by the optical fiber polarization controller; the polarization state is set to the adjustment state S1;

[0075] The controller synchronously collects the first voltage signal V output by the current-voltage converter PD1_i and the second voltage signal V output by the precision current detection unit PD_i ; The two voltages are divided to obtain the current polarization state result SD i :

[0076] SD i =V PD_i / V PD1_i ;

[0077] Record the current wavelength λ i When the power is P2, the polarization state result SD i The corresponding power values ​​are stored in the table. After the controller completes the storage, it adjusts the high-speed drive circuit in sequence to adjust the polarization state of the optical fiber polarization controller, obtaining a series of polarization state results SD0, SD1, ... SDn; and records the maximum value SD Max ;

[0078] 3) The computer changes the wavelength λ of the tunable source in sequence (traversing λ1, λ2, ..., λ i ,…,λ n Repeat step 2) for each wavelength and record the maximum value SD corresponding to each wavelength Max , and store, as Figure 3 As shown, it is used for subsequent lookup table in normal working mode;

[0079] After completing the target operating wavelength scan, the polarization-dependent loss calibration of the broadband high-speed photodetector is completed.

[0080] Through the above process, when the high-speed electro-optical signal under test is input, the polarization state of the input optical signal can be controlled in real time, ensuring that the polarization state connected to the broadband high-speed photodetector remains consistent with the calibration state. Regardless of how the polarization direction of the input signal changes, the polarization state direction of the current maximum response of the detector is obtained by detecting the current information of the photodetector and the voltage ratio of the I / V conversion of the other signal after PBS splitting. The controller constantly adjusts the optical fiber polarization controller to track the polarization state.

[0081] The present invention addresses the problem of poor response accuracy and repeatability caused by polarization-related loss due to the polarization state of the input electro-optical modulated signal in broadband high-speed photodetectors. A method and device for compensating for polarization loss in high-speed electro-optical response measurement are proposed. The device first calibrates the polarization loss of the broadband high-speed photodetector at a certain optical input power at different wavelengths. By tracking the input optical signal with the polarization state consistent with that at the time of calibration, the broadband photodetector can always be kept in a state consistent with that at the time of calibration and with maximum response. The present invention proposes an online power monitoring method for polarization misadjustment caused by fluctuations in the input optical power. Based on the difference between the acquired power and the power at the time of calibration, the polarization state maximum value is tracked and compensated in real time, thereby overcoming the misjudgment caused by changes in the input optical power and more accurately adjusting the polarization state of the electro-optical signal.

[0082] 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, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A polarization loss compensation device for high-speed electro-optical response measurement, characterized in that: The device comprises: A beam splitter is used to receive the electro-optical modulated signal to be measured and split the electro-optical modulated signal, wherein a portion of the split electro-optical modulated signal is transmitted to the optical fiber polarization controller, and another portion is transmitted to the second photodetector, and the second photodetector is connected to the power monitoring unit; An optical fiber polarization controller, connected to the optical beam splitter, configured to receive an electro-optical modulated signal and control the polarization state of the electro-optical modulated signal; A high-speed driving circuit, connected to the optical fiber polarization controller, for driving the optical fiber polarization controller to achieve high-speed adjustment of the optical fiber polarization state; a polarization beam splitter connected to the optical fiber polarization controller, the polarization beam splitter receiving the optical signal output by the optical fiber polarization controller and outputting two paths of orthogonal polarization state light; a broadband high-speed photodetector, which is a compensation object and is connected to the polarization beam splitter and receives one path of polarization state light from the polarization beam splitter; A first photodetector is connected to the polarization beam splitter to receive the other polarized light from the polarization beam splitter; the first photodetector is connected to a current-to-voltage converter; the first photodetector performs photocurrent detection on the polarized light and then converts the current-to-voltage converter into a first voltage signal; A precision current monitoring unit, connected to the broadband high-speed photodetector, for monitoring the photocurrent and outputting a second voltage signal; a divider connected to the precision current monitoring unit and the current-voltage converter, and dividing the second voltage signal and the first voltage signal to obtain a current polarization state result; The controller is connected to the divider, the high-speed driving circuit and the power monitoring unit.

2. The polarization loss compensation device for high-speed electro-optical response measurement according to claim 1, characterized in that: The beam splitter is a 1:99 beam splitter.

3. The polarization loss compensation device for high-speed electro-optical response measurement according to claim 1, characterized in that: The optical fiber polarization controller adopts a lithium niobate polarization controller.

4. A method for compensating polarization loss in high-speed electro-optical response measurement, using the device according to any one of claims 1 to 3, characterized in that: The method comprises: (1) performing polarization loss calibration on a broadband high-speed photodetector under conditions of a certain optical input power and different wavelengths, obtaining polarization state results corresponding to different wavelengths during the calibration phase, and storing the polarization state results; (2) After receiving the current target test optical signal, the controller will s , query the polarization state result SD of the corresponding wavelength stored during the calibration phase s ; The polarization state result SD s As the target value tracked during monitoring; (3) The controller starts the power monitoring unit to monitor the power of the current target test optical signal, obtains the current power value P2, compares the current power value P2 with the initial power P of the current target test optical signal, and obtains the power fluctuation ΔP of the current target test optical signal, ΔP=P2-P; Calculate the actual tracking target value SD s ’ for: SD s ’ =((V PD_s +ΔV PD ) / (V PD1_s +ΔV PD1 ))*(1-(ΔP / P)*K); Among them, V PD_s V is the second voltage signal output by the precision current monitoring unit before the power fluctuation ΔP occurs. PD1_s ΔV is the first voltage signal output by the current-voltage converter before the power fluctuation ΔP occurs; PD The voltage compensation output by the precision current monitoring unit after power fluctuation ΔP occurs; ΔV PD1 is the output voltage compensation of the current-to-voltage converter after the power fluctuation ΔP occurs; K is the linear response factor mapped from the power monitoring unit to the voltage signal; (4) The controller calculates the actual tracking target value SD s ’ SD with target value s Error|SD s ’ -SD s |, when |SD s ’ -SD s |Greater than the threshold SD Th When , the controller drives the fiber polarization controller to adjust the state once; (5) Repeat steps (3) to (4) until |SD s ’ -SD s The error signal of | satisfies |SD s ’ -SD s |Less than the threshold SD Th .

5. The method for compensating polarization loss in high-speed electro-optical response measurement according to claim 4, characterized in that: Step (1) is specifically as follows: 1) The tunable laser source is controlled by an external computer to achieve accurate setting of the target wavelength range. The calibration wavelengths of the tunable source are set to λ1, λ2, ..., λ i ,…,λ n , set the initial power of the tunable source wavelength to P; 2) When the calibrated wavelength of the tunable laser source output is λ i When the optical power P2 is measured by the power monitoring unit, the computer sends a command to the controller, and the controller controls the high-speed driving circuit to adjust the optical fiber polarization controller to adjust the polarization state of the input electrical signal; The controller synchronously collects the first voltage signal V output by the current-voltage converter PD1_i and the second voltage signal V output by the precision current detection unit PD_i ; The two voltages are divided to obtain the current polarization state result SD i : SD i =V PD_i / V PD1_i ; Record the current wavelength λ i When the power is P2, the polarization state result SD i The corresponding power values ​​are stored in the table. After the controller completes the storage, it adjusts the high-speed drive circuit in sequence to adjust the polarization state of the optical fiber polarization controller, obtaining a series of polarization state results SD0, SD1, ... SDn; and records the maximum value SD Max ; 3) The computer changes the wavelength λ of the tunable source in turn, repeats step 2), and records the maximum value SD corresponding to each wavelength Max , and store; calibration is completed.

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