Y waveguide chip extinction ratio measurement method and system based on birefringence dispersion compensation

Abstract

The present application belongs to the technical field of optical coherence domain polarization measurement, and particularly relates to a Y waveguide chip extinction ratio measurement method and system based on birefringence dispersion compensation. The Y waveguide chip extinction ratio measurement method based on birefringence dispersion compensation comprises the following steps: obtaining an interference signal of the Y waveguide chip extinction ratio affected by dispersion; compensating third-order birefringence dispersion based on the symmetry change of the interference signal area; compensating second-order birefringence dispersion based on the concentration change of the interference signal area after third-order birefringence dispersion compensation; and obtaining the Y waveguide chip extinction ratio based on the interference signal after second-order birefringence dispersion compensation. The present application analyzes the relationship between the interference signal shape change and third-order and second-order birefringence dispersion, gradually repairs third-order and second-order birefringence dispersion, so that the interference signal no longer distorts, and the measurement precision of the Y waveguide chip extinction ratio is improved.

Description

Technical Field

[0001] This invention belongs to the field of optical coherence domain polarization measurement technology, specifically relating to a method and system for measuring the extinction ratio of a Y-waveguide chip based on birefringence dispersion compensation. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] The multifunctional integrated optical chip (Y-waveguide) is one of the core optical components in fiber optic gyroscopes. The Y-waveguide highly integrates polarization, analysis, beam splitting, beam combining, and modulation functions into a single device. A single Y-waveguide can perform the functions of a single-mode fiber, a beam splitter, an electro-optic phase modulator, and an optical polarizer. Because the Y-waveguide can achieve multiple functions while maintaining a miniaturized size, it has gradually become a core component of high-precision inertial navigation sensing systems. The polarization and analysis performance of the Y-waveguide is mainly determined by the extinction ratio of the Y-waveguide chip. The higher the extinction ratio, the higher the inertial navigation sensing accuracy. Therefore, improving the extinction ratio is one of the key technical challenges in the development of Y-waveguides.

[0004] In the existing technology, it is proposed that the extinction ratio of Y waveguide chips can be improved by birefringence dispersion compensation. The traditional birefringence dispersion compensation method compensates for the third-order and second-order dispersions simultaneously, and then uses the Fourier transform algorithm to remove the dispersion effect. This method increases the difficulty of dispersion compensation and also increases the compensation time. Furthermore, there are no relevant parameters to feed back the compensation accuracy after the dispersion is compensated, resulting in low compensation accuracy. Summary of the Invention

[0005] To address the shortcomings of the existing technologies, this invention provides a method and system for measuring the extinction ratio of a Y-waveguide chip based on birefringence dispersion compensation. This invention analyzes the relationship between the shape change of the interference signal and the third-order and second-order birefringence dispersion, gradually repairs the third-order and second-order birefringence dispersion, so that the interference signal is no longer distorted, thereby improving the measurement accuracy of the extinction ratio of the Y-waveguide chip.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a method for measuring the extinction ratio of a Y-waveguide chip based on birefringence dispersion compensation, comprising the following steps:

[0008] Obtain the interference signal of the Y-waveguide chip affected by dispersion in terms of extinction ratio;

[0009] Third-order birefringence dispersion is compensated based on the symmetry variation of the interference signal area;

[0010] Second-order birefringence dispersion is compensated by the concentration change of the interference signal area after third-order birefringence dispersion compensation.

[0011] The extinction ratio of the Y-waveguide chip is obtained based on the interference signal after second-order birefringence dispersion compensation.

[0012] A further technical solution is that the interference signal of the Y waveguide chip extinction ratio affected by dispersion is the interference signal at the farthest point of the distributed interference signal; taking the highest point of the farthest interference signal as the center, the interference signals of 5000 data points on the left and right are extracted, and the interference signals of these 10001 data points are the complete interference signal V(x) corresponding to the chip extinction ratio.

[0013] A further technical solution, the method for compensating for third-order birefringence dispersion based on the symmetry variation of the interference signal area, includes:

[0014] The third-order dispersion coefficients are determined based on the interference signal V(x), and the interference signal V after compensating for k-order third-order dispersion values ​​is obtained based on the third-order dispersion coefficients. k (x), k is initially 1; calculate the interference signal V. k The symmetry S of (x) k If the symmetry S k If the preset conditions are met, then V k (x) is the interference signal V after third-order birefringence dispersion compensation. AfterTOD (x), if the symmetry S k If the preset conditions are not met, calculate V. k+1 The symmetry S of (x) k+1 The calculation is iterated continuously until the symmetry meets the preset condition, thus obtaining the interference signal V after third-order birefringence dispersion compensation. AfterTOD (x).

[0015] Preferably, the method for determining the third-order dispersion coefficient based on the interference signal V(x) includes: obtaining the compensated interference signal V′(x) based on the compensated third-order dispersion value TOD of the interference signal V(x), and calculating the symmetry S and S′ of V(x) and V'(x) respectively; if S′>S, then the third-order dispersion coefficient is determined to be TOD, and if S′<S, then the third-order dispersion coefficient is determined to be -TOD.

[0016] Preferably, the symmetry S k The preset condition is |S k -1∣<0.01.

[0017] A further technical solution, as shown, is a method for compensating for second-order birefringence dispersion based on the concentration change of the interference signal area after third-order birefringence dispersion compensation, including:

[0018] The second-order dispersion coefficient is determined based on the interference signal after third-order birefringence dispersion compensation; the interference signal V after j-order second-order dispersion compensation is obtained based on the second-order dispersion coefficient. j (x), j is initially 1; calculate the interference signal V j Concentration C of (x) j If the concentration C j If the preset conditions are met, then V j (x) is the interference signal V after second-order birefringence dispersion compensation. PER If the concentration C j If the preset conditions are not met, calculate V. j+1 Concentration C of (x) j+1 The calculation is iterated continuously until the concentration meets the preset conditions, thus obtaining the interference signal V after second-order birefringence dispersion compensation. PER (x).

[0019] Preferably, the method for determining the second-order dispersion coefficient based on the interference signal after third-order birefringence dispersion compensation includes: based on the interference signal V after eliminating the influence of third-order dispersion. AfterTOD (x) The second-order dispersion value is compensated by SED to obtain the compensated interference signal V'. AfterTOD (x), calculate V respectively AfterTOD (x) and V' AfterTOD The concentrations C and C′ of (x) are determined. If C′>C, the second-order dispersion coefficient is determined to be SED. If C′<C, the second-order dispersion coefficient is determined to be -SED.

[0020] Preferably, the concentration C j The preset condition is |C j -1∣<0.01.

[0021] A further technical solution, the method for obtaining the extinction ratio of a Y-waveguide chip based on the interference signal after second-order birefringence dispersion compensation, includes: based on the interference signal V after second-order birefringence dispersion compensation... PER (x) Obtain the maximum value of the interference signal after dispersion compensation, max(V) PER ).

[0022] A second aspect of the present invention provides a Y-waveguide chip extinction ratio measurement system based on birefringence dispersion compensation, comprising:

[0023] Interference signal acquisition module: used to acquire the interference signal of the Y waveguide chip affected by dispersion in terms of extinction ratio;

[0024] Third-order birefringence dispersion compensation module: used to compensate for third-order birefringence dispersion based on the symmetry variation of the interference signal area;

[0025] Second-order birefringence dispersion compensation module: used to compensate for second-order birefringence dispersion based on the concentration change of the interference signal area after third-order birefringence dispersion compensation;

[0026] The module for obtaining the extinction ratio of a Y-waveguide chip is based on the interference signal after second-order birefringence dispersion compensation.

[0027] The above technical solutions have the following beneficial effects:

[0028] (1) Before measuring the extinction ratio of the Y waveguide chip, this invention analyzes the relationship between the shape change of the interference signal and the third-order and second-order birefringence dispersion, and gradually repairs the third-order and second-order birefringence dispersion so that the interference signal no longer becomes distorted, thereby improving the measurement accuracy of the extinction ratio of the Y waveguide chip.

[0029] (2) The extinction ratio measurement method of Y waveguide chip based on birefringence dispersion compensation provided by the present invention can improve the measurement accuracy of Y waveguide chip from about ±1dB to about ±0.1dB, thereby improving the measurement accuracy of Y waveguide chip extinction ratio and facilitating the further development of Y waveguide in the field of high-precision inertial navigation.

[0030] (3) The extinction ratio measurement method of Y waveguide chip based on birefringence dispersion compensation provided by the present invention adopts a closed-loop method for dispersion compensation, which improves the compensation accuracy; the second-order and third-order birefringence dispersions are compensated separately and independently, which improves the compensation efficiency; the dispersion compensation is performed by utilizing the change of the interference signal area, which can eliminate the influence of noise on dispersion compensation and improve the dynamic range of dispersion compensation. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0032] Figure 1 This is a flowchart of a method for measuring the extinction ratio of a Y-waveguide chip based on birefringence dispersion compensation, as provided in Example 1.

[0033] Figure 2 This is a connection diagram of the Y-waveguide chip and the white light interferometry system in Example 1;

[0034] Figure 3 This is an interference signal diagram showing the effects of second-order and third-order birefringence dispersion in Example 1;

[0035] Figure 4 This is a graph showing the change of the area ratio of the interference signal V(x) as a function of coordinate x in Example 1;

[0036] Figure 5 The interference signal V in Example 1k The symmetry S of (x) k The graph shows the change with the number of iterations k;

[0037] Figure 6 This is the interference signal diagram of Example 1 after third-order birefringence dispersion compensation, which is only affected by second-order birefringence dispersion.

[0038] Figure 7 The interference signal V in Example 1 j Concentration C of (x) j The graph shows the change with the number of iterations j;

[0039] Figure 8 The image shows the interference signal diagrams after third-order and second-order birefringence dispersion compensation in Example 1. Detailed Implementation

[0040] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0041] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0042] Example 1

[0043] like Figure 1 The flowchart shown illustrates a method for measuring the extinction ratio of a Y-waveguide chip based on birefringence dispersion compensation, comprising the following steps:

[0044] (1) Obtain the interference signal of the extinction ratio of the Y waveguide chip affected by dispersion;

[0045] (2) Compensation for third-order birefringence dispersion based on the symmetry variation of the interference signal area;

[0046] (3) Compensate for second-order birefringence dispersion based on the concentration change of the interference signal area after third-order birefringence dispersion compensation;

[0047] (4) Obtain the extinction ratio of the Y waveguide chip based on the interference signal after second-order birefringence dispersion compensation.

[0048] In this embodiment, the method for obtaining the interference signal of the Y-waveguide chip extinction ratio affected by dispersion in step (1) is as follows: Figure 2As shown, after connecting the Y-waveguide chip to the white light interferometry system, distributed interference signals corresponding to the internal coupling points of the Y-waveguide and the chip extinction ratio are obtained. The interference signal affected by dispersion of the Y-waveguide chip extinction ratio is the interference signal at the furthest point of the distributed interference signal. Taking the highest point of the furthest interference signal as the center, interference signals of 5000 data points on both sides are extracted. The interference signals of these 10001 data points are the complete interference signal V(x) corresponding to the chip extinction ratio. Figure 3 As shown, the interference signal V(x) is distorted due to the influence of birefringence dispersion.

[0049] In step (2), the compensated interference signal V′(x) is obtained based on the third-order dispersion value TOD of the interference signal V(x). The symmetry S and S′ of V(x) and V′(x) are calculated respectively. If S′>S, the third-order dispersion coefficient is determined to be TOD; if S′<S, the third-order dispersion coefficient is determined to be -TOD. The interference signal V after k-fold compensation of the third-order dispersion value is obtained based on the third-order dispersion coefficient. k (x), k is initially 1; calculate the interference signal V. k The symmetry S of (x) k If the symmetry S k Satisfying preset conditions |S k -1|<0.01, then V k (x) is the interference signal V after third-order birefringence dispersion compensation. AfterTOD (x), if the symmetry S k If the preset conditions are not met, calculate V. k+1 The symmetry S of (x) k+1 The calculation is iterated continuously until the symmetry meets the preset condition, thus obtaining the interference signal V after third-order birefringence dispersion compensation. AfterTOD (x).

[0050] The formula for compensating the third-order dispersion value TOD by the interference signal V(x) is as follows: TOD = 1 × 10 4 fs 3 The third-order dispersion value TOD can cause a change in the symmetry of the interference signal within 1%. The calculation of the symmetry S involves: calculating the ratio of the area Area(x) of the interference signal V(x) to the position x, then obtaining position x1 at Area(x) = 0.01, position x2 at Area(x) = 0.50, and position x3 at Area(x) = 0.99, and finally calculating the symmetry S using the following formula: The formula for the area Area(x) of the interference signal V(x) is: The interference signal V obtained after compensating for k-th order third-order dispersion values ​​is based on the third-order dispersion coefficient. k The formula for (x) is:

[0051] In this embodiment, the variation of the area ratio of the interference signal V(x) with coordinate x is shown in the figure below. Figure 4 As shown, from Figure 4 The position x1 = 4000 is found at the location where Area(x) = 0.01, the position x2 = 5000 is found at the location where Area(x) = 0.50, and the position x3 = 6500 is found at the location where Area(x) = 0.99. The symmetry S is calculated using the formula for symmetry S = 0.667. The compensated interference signal V′(x) is obtained by compensating the third-order dispersion value TOD using the interference signal V(x), and the symmetry S′ of the compensated interference signal V′(x) is calculated to be 0.672. Since S′ > S, the third-order dispersion coefficient is determined to be TOD. The interference signal V after compensating for k times the third-order dispersion value is obtained based on the third-order dispersion coefficient. k (x), interference signal V k The symmetry S of (x) k The graph shows the change with the number of iterations k. Figure 5 As shown, the initial value of k is 1, from Figure 5 It can be seen that the symmetry is best when the number of iterations k=43, and the interference signal V 43 (x) is the interference signal V after third-order birefringence dispersion compensation. AfterTOD The interference signal V after third-order birefringence dispersion compensation AfterTOD like Figure 6 As shown, the interference signals are in a symmetrical state.

[0052] In step (3), based on the interference signal V after eliminating the influence of third-order dispersion AfterTOD (x) The second-order dispersion value is compensated by SED to obtain the compensated interference signal V'. AfterTOD (x), calculate V respectively AfterTOD (x) and V' AfterTOD The concentrations C and C′ of (x) are determined. If C′ > C, the second-order dispersion coefficient is determined to be SED; if C′ < C, the second-order dispersion coefficient is determined to be -SED. Based on the second-order dispersion coefficient, the interference signal V after compensating for j-th order second-order dispersion values ​​is obtained. j (x), j is initially 1; calculate the interference signal V j Concentration C of (x) j If the concentration C j Satisfying preset conditions | C j -1|<0.01, then V j (x) is the interference signal V after second-order birefringence dispersion compensation. PERIf the concentration C j If the preset conditions are not met, calculate V. j+1 Concentration C of (x) j+1 The calculation is iterated continuously until the concentration meets the preset conditions, thus obtaining the interference signal V after second-order birefringence dispersion compensation. PER (x).

[0053] Among them, the interference signal V AfterTOD The second-order dispersion value SED is compensated to obtain the compensated interference signal V'. AfterTOD The formula is: SED = 5 × 10 2 fs 2 The second-order dispersion value (SED) can cause a change in the concentration of the interference signal within 1%. The formula for calculating the concentration C includes: finding the amplitude value max(V(x)) at the highest point of the interference signal, then finding the positions x4 and x5 where the interference signal amplitude is at max(V(x)) / 2, and using the formula: The calculation is performed, where Width in the formula represents the coherence length of the light source. The default coherence length is 50 μm, and the specific value can be obtained from the light source's product manual. The interference signal V is obtained after compensating for the j-th order second-order dispersion value based on the second-order dispersion coefficient. j The formula for (x) is:

[0054] In this embodiment, the amplitude value max(V(x)) at the highest point of the interference signal is found. Then, the position points x4 and x5 of the interference signal amplitude at the position of max(V(x)) / 2 are found, where x4 = 4450 and x5 = 5550. In this embodiment, the Width of the light source is 1770, and the concentration C = 0.620 is calculated. Using the interference signal V... AfterTOD The second-order dispersion value SED is compensated to obtain the compensated interference signal V'. AfterTOD And calculate the compensated interference signal V' AfterTOD The concentration C' = 0.625. Since C' > C, the second-order dispersion coefficient is determined to be SED. Based on the second-order dispersion coefficient, the interference signal V after compensating for j-th second-order dispersion values ​​is obtained. j (x), interference signal V j Concentration C of (x) j The change with the number of iterations j is as follows Figure 7 As shown, the initial value of j is 1, from... Figure 7 It can be seen that the concentration is best when the number of iterations j = 46, and the interference signal V 46 (x) is the interference signal V after second-order birefringence dispersion compensation. PER (x). For example... Figure 8 As shown, the interference signals are in a symmetrical and concentrated state.

[0055] In step (4), the interference signal V is based on the second-order birefringence dispersion compensation. PER (x) Obtain the maximum value of the interference signal after dispersion compensation, max(V) PER ).

[0056] The formula is PER = 10 × log10(max(V) PER (x))) 2 .

[0057] In this embodiment, the maximum value of the interference signal, max(V), is read. PER Given 0.003, the calculated extinction ratio is 50.45 dB. The maximum value of the interference signal before compensation is max(V). PER =0.0025, and the calculated extinction ratio is 52.04dB, which is an improvement of 1.59dB compared with before and after compensation.

[0058] Example 2

[0059] A Y-waveguide chip extinction ratio measurement system based on birefringence dispersion compensation, comprising:

[0060] Interference signal acquisition module: used to acquire the interference signal of the Y waveguide chip affected by dispersion in terms of extinction ratio;

[0061] Third-order birefringence dispersion compensation module: used to compensate for third-order birefringence dispersion based on the symmetry variation of the interference signal area;

[0062] Second-order birefringence dispersion compensation module: used to compensate for second-order birefringence dispersion based on the concentration change of the interference signal area after third-order birefringence dispersion compensation;

[0063] The module for obtaining the extinction ratio of a Y-waveguide chip is based on the interference signal after second-order birefringence dispersion compensation.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0065] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for measuring the extinction ratio of a Y-waveguide chip based on birefringence dispersion compensation, characterized in that, Includes the following steps: Obtain the interference signal of the Y-waveguide chip affected by dispersion in terms of extinction ratio; Third-order birefringence dispersion is compensated based on the symmetry variation of the interference signal area; Second-order birefringence dispersion is compensated by the concentration change of the interference signal area after third-order birefringence dispersion compensation. The extinction ratio of the Y-waveguide chip is obtained from the interference signal after second-order birefringence dispersion compensation. The symmetry The calculations include: calculating the interference signal. area Proportion varies with position The changes, and then obtain The position at =0.01 ,get The position at =0.50 ,get The position at =0.99 Using the following symmetry Calculate using the formula: ; The concentration The calculation formula includes: finding the maximum amplitude value at the highest point of the interference signal (max). Then find the amplitude of the interference signal at... Location point and Using the formula: Perform calculations, where the formula contains This is the coherence length of the light source, which is 50 μm by default. The method for compensating for third-order birefringence dispersion based on the symmetry variation of the interference signal area includes: calculating the interference signal. symmetry If symmetry If the preset conditions are met, then The interference signal after third-order birefringence dispersion compensation If symmetry If the preset conditions are not met, then calculate. symmetry The calculation is iterated continuously until the symmetry meets the preset condition, thus obtaining the interference signal after third-order birefringence dispersion compensation. ; The method for compensating for second-order birefringence dispersion based on the concentration change of the interference signal area after third-order birefringence dispersion compensation includes: Calculate the interference signal Concentration If concentration If the preset conditions are met, then The interference signal after second-order birefringence dispersion compensation If concentration If the preset conditions are not met, then calculate. Concentration The calculation is iterated continuously until the concentration meets the preset conditions, thus obtaining the interference signal after second-order birefringence dispersion compensation. .

2. The method for measuring the extinction ratio of a Y-waveguide chip based on birefringence dispersion compensation as described in claim 1, characterized in that, The interference signal affected by dispersion in the extinction ratio of the Y-waveguide chip is the interference signal at the furthest point of the distributed interference signal. Taking the highest point of the furthest interference signal as the center, interference signals of 5000 data points on each side are extracted. These 10001 data points constitute the complete interference signal corresponding to the chip's extinction ratio. .

3. The method for measuring the extinction ratio of a Y-waveguide chip based on birefringence dispersion compensation as described in claim 1, characterized in that, The method for compensating for third-order birefringence dispersion based on the symmetry variation of the interference signal area includes: based on the interference signal... Determine the third-order dispersion coefficients and obtain compensation based on them. Interference signal after the second-third dispersion value , The initial value is 1.

4. The method for measuring the extinction ratio of a Y-waveguide chip based on birefringence dispersion compensation as described in claim 3, characterized in that, The interference signal-based Methods for determining the third-order dispersion coefficients include: based on interference signals Compensated interference signal is obtained by compensating the third-order dispersion value TOD. Calculate separately and symmetry and ;if > Then the third-order dispersion coefficient is determined to be TOD, if < Therefore, the third-order dispersion coefficient is determined to be -TOD.

5. The method for measuring the extinction ratio of a Y-waveguide chip based on birefringence dispersion compensation as described in claim 3, characterized in that, The symmetry The preset conditions are .

6. The method for measuring the extinction ratio of a Y-waveguide chip based on birefringence dispersion compensation as described in claim 1, characterized in that, The method for compensating for second-order birefringence dispersion based on the concentration change of the interference signal area after third-order birefringence dispersion compensation includes: The second-order dispersion coefficient is determined based on the interference signal after third-order birefringence dispersion compensation; the interference signal after j-order second-order dispersion compensation is obtained based on the second-order dispersion coefficient. The initial value of j is 1.

7. The method for measuring the extinction ratio of a Y-waveguide chip based on birefringence dispersion compensation as described in claim 6, characterized in that, The method for determining the second-order dispersion coefficient based on the interference signal after third-order birefringence dispersion compensation includes: based on the interference signal after eliminating the influence of third-order dispersion. The SED (Self-Diagnosis Electron Microscopy) was used to obtain the compensated interference signal after compensating for the second-order dispersion. Calculate separately and Concentration and ,if > Then the second-order dispersion coefficient is determined to be SED, if < Therefore, the second-order dispersion coefficient is determined to be -SED.

8. The method for measuring the extinction ratio of a Y-waveguide chip based on birefringence dispersion compensation as described in claim 6, characterized in that, The concentration The preset conditions are .

9. The method for measuring the extinction ratio of a Y-waveguide chip based on birefringence dispersion compensation as described in claim 1, characterized in that, The method for obtaining the extinction ratio of a Y-waveguide chip based on the interference signal after second-order birefringence dispersion compensation includes: based on the interference signal after second-order birefringence dispersion compensation The maximum value of the interference signal after obtaining the dispersion compensation .

10. A Y-waveguide chip extinction ratio measurement system based on birefringence dispersion compensation, characterized in that, include: Interference signal acquisition module: used to acquire the interference signal of the Y waveguide chip affected by dispersion in terms of extinction ratio; Third-order birefringence dispersion compensation module: used to compensate for third-order birefringence dispersion based on the symmetry variation of the interference signal area; Second-order birefringence dispersion compensation module: used to compensate for second-order birefringence dispersion based on the concentration change of the interference signal area after third-order birefringence dispersion compensation; The module for obtaining the extinction ratio of a Y-waveguide chip: The extinction ratio of the Y-waveguide chip is obtained based on the interference signal after second-order birefringence dispersion compensation; The symmetry The calculations include: calculating the interference signal. area Proportion varies with position The changes, and then obtain The position at =0.01 ,get The position at =0.50 ,get The position at =0.99 Using the following symmetry Calculate using the formula: ; The concentration The calculation formula includes: finding the maximum amplitude value at the highest point of the interference signal (max). Then find the amplitude of the interference signal at... Location point and Using the formula: Perform calculations, where the formula contains This is the coherence length of the light source, which is 50 μm by default. The method for compensating for third-order birefringence dispersion based on the symmetry variation of the interference signal area includes: calculating the interference signal. symmetry If symmetry If the preset conditions are met, then The interference signal after third-order birefringence dispersion compensation If symmetry If the preset conditions are not met, then calculate. symmetry The calculation is iterated continuously until the symmetry meets the preset condition, thus obtaining the interference signal after third-order birefringence dispersion compensation. ; The method for compensating for second-order birefringence dispersion based on the concentration change of the interference signal area after third-order birefringence dispersion compensation includes: Calculate the interference signal Concentration If concentration If the preset conditions are met, then The interference signal after second-order birefringence dispersion compensation If concentration If the preset conditions are not met, then calculate. Concentration The calculation is iterated continuously until the concentration meets the preset conditions, thus obtaining the interference signal after second-order birefringence dispersion compensation. .

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