CN105841928A - High extinction ratio measurement method for optical fiber polarizer - Google Patents

Abstract

The design of the invention belongs to the technical field of optical fiber measurement, and in particular relates to a method for measuring high extinction ratio of an optical fiber polarization device. A high extinction ratio measurement method of an optical fiber polarization device, in which two sections of polarization-maintaining optical fiber with different lengths are respectively welded at the input and output ends of a Y waveguide to be tested to form a measurement component with a quantitative crosstalk mark; welding When using the lumped extinction ratio tester to quantitatively control the extinction ratio of the welding point and record its measured value, at the same time, the polarizer tail fiber, analyzer tail fiber, high extinction ratio polarization device tail fiber, welding polarization maintaining fiber The length is set; the measurement component is connected to the distributed optical fiber polarization crosstalk test device, and the extinction ratio of the polarization device to be tested is calibrated and self-calibrated by using the second-order crosstalk measurement value between the external optical fiber welding points. During the measurement process, the crosstalk mark and the measurement peak can be measured synchronously, eliminating errors introduced by changes in the measurement environment and device connection accuracy.

Description

A High Extinction Ratio Measuring Method of Optical Fiber Polarizer

technical field

The design of the invention belongs to the technical field of optical fiber measurement, and in particular relates to a method for measuring high extinction ratio of an optical fiber polarization device.

Background technique

Polarization optical devices are an important part of high-precision optical measurement and sensing systems. At present, the performance testing and evaluation methods and devices of optical devices are backward, which seriously hinders the development of high-precision optical measurement and sensing systems. For example, the chip extinction ratio of lithium niobate integrated waveguide modulator (commonly known as Y waveguide), the core device of high-precision fiber optic gyroscope, has reached more than 80dB; The rate is about 50dB (according to the definition of energy, it is 10 ⁵ ), and the highest resolution is the Model 4810 polarization extinction ratio measuring instrument developed by the US company dBm Optics, and its measurement limit is only 72dB.

Optical coherent domain polarization measurement technology (OCDP) is a high-precision distributed polarization coupling measurement technology. It is based on the principle of wide-spectrum light interference and uses scanning optical interferometers for optical path compensation to achieve interference between different polarization modes. The spatial position of the polarization crosstalk and the intensity of the polarization coupling signal are measured and analyzed with high precision, and then important parameters such as the extinction ratio and the beat length of the optical polarization device are obtained. As a very promising detection method for distributed optical polarization performance, OCDP technology is widely used in the fields of polarization-maintaining optical fiber manufacturing, accurate alignment of polarization-maintaining optical fiber, and device extinction ratio testing. Compared with other distributed detection methods and technologies such as Polarized Time Domain Reflectometry (POTDR), Optical Frequency Domain Reflectometry (OFDR), and Optical Coherent Domain Reflectometry (OCDR), OCDP technology has simple structure and high spatial resolution ( 5 ~ 10cm), large measurement range (measurement length of several kilometers), ultra-high measurement sensitivity (coupling energy -80 ~ -100dB), ultra-large dynamic range (10 ⁸ ~ 10 ¹⁰ ), etc., it is very promising to develop into a high Accuracy, generalization testing techniques and systems. Because it most directly and truly describes the transmission behavior of signal light in the optical fiber optical path, it is especially suitable for testing and evaluating high-precision and ultra-high-precision interferometric optical fiber sensing optical circuits such as optical fiber devices, components, and fiber optic gyroscopes.

In the early 1990s, French Herve Lefevre et al. [Method for the detection of polarization couplings in a birefringent optical system and application of this method to the assembling of the components of an optical system, US Patent 4863631] disclosed for the first time based on the principle of white light interference OCDP system, which uses superluminescent light-emitting diode (SLD) as light source and spatial interference optical path as optical path correlation measurement structure. According to this patent, the French Photonetics company has developed two types of OCDP test systems, WIN-P 125 and WIN-P 400, which are mainly used for the analysis of the polarization characteristics of shorter (500m) and longer (1600m) polarization-maintaining optical fibers. Its main performance is that the polarization crosstalk sensitivity is -70dB and the dynamic range is 70dB. After improvement, the sensitivity and dynamic range are increased to -80dB and 80dB respectively.

In 2011, Zhang Hongxia of Tianjin University and others disclosed a detection method and detection device for the polarization extinction ratio of an optical polarization device (Chinese patent application number: 201110052231.3), which also uses the spatial interference optical path as the core device of OCDP, by detecting the coupling of the coupling point Intensity, the polarization extinction ratio is derived. The device is suitable for various optical polarization devices such as polarization-maintaining fiber, polarization-maintaining fiber coupler, and polarizer. Compared with the scheme of Herve Lefevre et al., the technical performance and index are similar.

In the same year, people such as Yao Xiaotian of General Photonics Corporation of the United States disclosed an all-fiber measurement system (US20110277552, Measuring Distributed Polarization Crosstalk in Polarization Maintaining Fiber and Optical Birefringent Material), using an optical path retarder before the optical path correlator to suppress the number and magnitude of stray white light interference signals in the measurement of polarization crosstalk. This method can improve the polarization crosstalk sensitivity of the all-fiber measurement system to -95dB, but maintain the dynamic range at 75dB.

In 2012, the applicant of the present invention disclosed a device and method for improving the performance of polarization crosstalk measurement of optical devices (Chinese patent application number CN201210379407.0) and an all-fiber test device for polarization crosstalk measurement of optical devices (CN201210379406.6), Adopt all-fiber optical path correlator structure, add polarization beam splitting and online rotating connection function, suppress beat noise, effectively improve measurement sensitivity, add Faraday rotator in the correlator, increase the stability of the light source, and improve the utilization rate of the light source power. The above two devices are suitable for performance testing of various polarized devices. Compared with General Optoelectronics Corporation of the United States, the polarization crosstalk sensitivity of the measurement system can be increased to -95dB while maintaining the dynamic range at better than 95dB. Sensitivity is already close to the measurement limit, mainly limited by the relative intensity noise of the light source. Without changing the optical path structure and optimizing the strength of component parameters, the measurement sensitivity will not be further improved.

In 2013, the applicant of the present invention proposed a large-scan range optical coherence domain polarization measurement device (Chinese patent application number CN201310736313.4), which uses multiple continuous optical path extension units to cascade, and makes the scanning optical device in the unit They appear in pairs to realize the expansion of optical path scanning and suppress the influence of scanner intensity fluctuation on measurement. The main problem to be solved is how to improve the accuracy and stability of polarization crosstalk measurement, and the measurement sensitivity performance has not been improved.

In 2014, the applicant of the present invention proposed an optical coherent polarization measurement device that can suppress interference noise (Chinese patent application number CN201410120901.4), which uses an all-fiber polarization state controller to eliminate the residual light reflection of optical devices, and uses a Faraday rotator The optical path demodulation device overcomes the polarization fading effect in interference and effectively suppresses interference noise; proposes an optical coherent domain polarization measurement device with optical path scanning position and velocity correction (Chinese Patent Application No. CN201410120591.6), by adjusting the optical path The scanning correction improves the spatial precision and detection sensitivity of the polarization measuring device.

It is the unremitting pursuit of scientific measurement to continuously improve the performance test accuracy of polarization devices, especially for devices with high extinction ratio (such as Y waveguide, etc.). In the process of system construction, due to the connection of devices, there will inevitably be non-ideal defects at the connection points. How to weaken or correctly use these defect points is a very important content. Before welding, use the extinction ratio tester to set the crosstalk caused by the alignment angle to mark, and reasonably intercept the length of the polarization-maintaining fiber to construct a second-order interference peak with high extinction ratio to achieve the purpose of accurate measurement of high extinction ratio devices.

The invention provides a high extinction ratio measurement method of an optical fiber polarization device. By monitoring the length of the polarization-maintaining optical fiber in the measuring device and the alignment angle of the polarization-maintaining optical fiber during welding, a 45° polarizer, a polarization-maintaining optical fiber, and a 45° The analyzer is connected to the measurement components that constitute the quantitative crosstalk mark, so that the online calibration measurement of the extinction ratio can be realized, and the purpose of accurate measurement of the polarization device with high extinction ratio can be achieved.

Contents of the invention

The object of the present invention is to provide a high extinction ratio measurement method of an optical fiber polarization device that has the characteristics of high precision, stability and reliability, and can be used for a polarization performance measuring instrument of a high-precision optical device (Y waveguide) to accurately measure.

The purpose of the present invention is achieved like this:

A high extinction ratio measurement method of an optical fiber polarization device, in which two sections of polarization-maintaining optical fiber with different lengths are respectively welded at the input and output ends of a Y waveguide to be tested to form a measurement component with a quantitative crosstalk mark; welding When using the lumped extinction ratio tester to quantitatively control the extinction ratio of the welding point and record its measured value, at the same time, the polarizer tail fiber, analyzer tail fiber, high extinction ratio polarization device tail fiber, welding polarization maintaining fiber The length is set; the measurement component is connected to the distributed optical fiber polarization crosstalk test device, and the extinction ratio of the polarization device to be tested is calibrated and self-calibrated by using the second-order crosstalk measurement value between the welding points of the external optical fiber; including the following steps:

(1) Input the light beam from the input terminal y1 of the Y waveguide 113, and use the lumped extinction ratio tester to measure the C-point crosstalk PER _c value;

(2) Take the length of the output end y2 of the Y waveguide 113 as l ₃ , and the length of the polarization-maintaining fiber 115 as l ₂ , use a polarization-maintaining welding machine to align, and use the lumped extinction ratio test for the output beam of the polarization-maintaining fiber 115 The measured extinction ratio is PER _b +PER _c ; rotate the alignment angle to make the PER _b amount reach the set value, weld the output end y2 of the Y waveguide 113 to the polarization-maintaining optical fiber 115, and record the value at this time _PERb ;

(3) input the light beam from the polarization-maintaining fiber 115, and measure the D-point crosstalk PER _d value with a lumped extinction ratio tester;

(4) The length of the input end y1 of the Y waveguide 113 is taken as l ₄ , the length of the polarization maintaining fiber 114 is taken as l ₅ , aligned using a polarization maintaining welding machine, and the output beam of the polarization maintaining fiber 114 is tested with a lumped extinction ratio Real-time measurement by the instrument, the measured extinction ratio is PER _d +PER _e ; rotate the alignment angle to make the PER _b amount reach the set value, weld the input end y1 of the Y waveguide 113 to the polarization maintaining optical fiber 114, and record the value at this time PER _e .

( ₅ ) The _lengths of the 45° polarizer 111 polarization-maintaining pigtail ps1 and the 45° Polarization fiber 114, 45° polarizer 111 polarization maintaining pigtail ps2 and polarization maintaining fiber 115 are aligned and welded at 0° to 0°;

(6) Connecting the wide-spectrum light source and the power monitoring device 100, the optical path correlator 130, and the polarization crosstalk detection and signal recording device 140;

(7) Turn on the wide-spectrum light source 101, adjust the polarization state controller 132 and the optical scanner 133 to the maximum state of the interference signal, drive the optical path scanner 133, and use the polarization crosstalk detection and signal recording device 140 to be different from the optical path correlator 130. Measure and record the data of the scanning distance, obtain the measurement results of distributed polarization crosstalk, and record the background data of polarization crosstalk noise in the measurement spectrum and the position and amplitude of each interference peak;

(8) Normalize the interferogram data, and compare the position and height of the first-order interference peaks on both sides of the main interference peak; according to the known interception lengths l ₁ , l ₂ , l ₃ , l ₄ , l ₅ , l ₆ , using the relational expression:

τ=Δn _f l

Get the ρ _A , ρ _B , ρ _C corresponding to the positions of τ _l1 , τ _l1 +τ _l2 , τ _l1 +τ _l2 +τ _l3 , τ _l4 +τ _l5 +τ _l6 , τ _l5 +τ _l6 , τ _l6 , ρ _D , ρ _E , and ρ _F peak amplitudes, and calibrated and self-calibrated the values of PER _b and ρ _B , PER _c and ρ _C , PER _d and ρ _D , PER _e and ρ _E , and obtained each first-order exact value of the crosstalk peak;

The optical path delay is 0, The crosstalk coefficients are 1, ρ _A , ρ _B , ρ _C , ρ _D , ρ _E , ρ _F ;

(9) On the basis of the first-order interference peak, through calculation, it is obtained that τ _l1 +τ _l4 +τ _l5 +τ _l6 , τ _l1 +τ _l2 +τ _l4 +τ _l5 +τ _l6 , τ _l1 +τ _l2 + ρ _A + ρ _D , ρ _B corresponding to the positions of τ _l3 +τ _l4 +τ _l5 +τ _l6 , τ _l1 +τ _l2 +τ _l3 +τ _l5 +τ _l6 , τ _l1 +τ _l2 +τ _l3 +τ _l6 +ρ _D , ρ _C +ρ _D , ρ _C +ρ _E , ρ _C +ρ _F peak size are compared with the peak position and amplitude in the spectrum to obtain the exact value of each second-order crosstalk peak, which is used for Calibration and self-calibration of the high extinction ratio area; the optical path delay is The crosstalk coefficients are ρ _A + ρ _D , ρ _B + ρ _D , ρ _C + ρ _D , ρ _C + ρ _E , ρ _C + ρ _F ;

(10) By measuring the peak amplitude at τ _l1 +τ _l2 +τ _l3 +τ _l4 +τ _l5 +τ _l6 +τ _lY , which is the outermost part of the interference pattern, the precise value of the extinction ratio of the Y waveguide to be measured is obtained, and the precise Measurement, Optical Path Retardation The crosstalk coefficient of ε _chip .

The 45° polarization analyzer 116 polarization maintaining pigtail ps2, polarization maintaining fiber 115, output end y2 of Y waveguide 113, input end y1 of Y waveguide 113, polarization maintaining optical fiber 114, 45° polarizer 111 polarization maintaining pigtail The selection of lengths l ₁ , l ₂ , l ₃ , l ₄ , l ₅ , and l ₆ of ps1 satisfies four relationships:

1) Ensure that the corresponding first-order and second-order interference peaks in the interferogram are staggered in the interferogram:

l ₁ ≠l ₆ ≠l ₁ +l ₂ ≠l ₅ +l ₆ ≠l ₁ +l ₆

≠l ₁ +l ₂ +l ₃ ≠l ₁ +l ₂ +l ₆

≠l ₁ +l ₅ +l ₆ ≠l ₄ +l ₅ +l ₆

≠l ₁ +l ₄ +l ₅ +l ₆ ≠l ₁ +l ₂ +l ₃ +l ₆ ≠l ₁ +l ₂ +l ₅ +l ₆ ;

≠l ₁ +l ₂ +l ₄ +l ₅ +l ₆ ≠l ₁ +l ₂ +l ₃ +l ₅ +l ₆

≠l ₁ +l ₂ +l ₃ +l ₄ +l ₅ +l ₆

≠l ₁ +l ₂ +l ₃ +l ₄ +l ₅ +l ₆ +l _Y

2) The optical path difference of the input polarization-maintaining fiber y1 length L _in of the Y waveguide 113 is greater than the optical path L _r of the ripple coherence peak of the broadband light source 101, that is: L _in ×Δn _f >L _r , and _Lin is the input pigtail y1, the sum of the lengths of the polarization-maintaining fiber 114 and the 45° polarizer polarization-maintaining pigtail ps1, Δnf is the linear birefringence of the polarization-maintaining fiber;

3) The optical path difference of the output polarization maintaining fiber y2 length L _out of the Y waveguide 113 is greater than the optical path difference between the fast and slow axes of the Y waveguide 113 itself, that is: L _out ×Δn _f >L _Y ×Δn _Y ; L _out is the output The sum of the lengths of pigtail y2, polarization maintaining fiber 115, and polarization maintaining pigtail ps2 of the 45° analyzer; L _Y is the length of the Y waveguide, and Δn _Y is the linear birefringence of the Y waveguide;

4) Measured optical path scanning range ΔL

ΔL>2(L _in +L _Y +L _out )

The midpoint of the optical path scanning range is the position of the maximum peak value of the polarization crosstalk measurement data.

Compared with prior art, the beneficial effect of the present invention is:

(1) By reasonably selecting the length of the polarization-maintaining fiber, suppressing the influence of light source ripple and fiber noise, using the extinction ratio tester, in the process of building a high-precision test device, the connection point (solder point) in the polarization-maintaining fiber The extinction ratio is adjusted, the first-order interference peak is quantitatively constructed, and the second-order interference peak is used to quantitatively mark the high extinction ratio area to achieve the purpose of accurate measurement.

(2) During the measurement process, the crosstalk mark and the measurement peak can be measured synchronously, eliminating errors introduced by changes in the measurement environment and device connection accuracy.

(3) Utilize the cut-off characteristic of the high extinction ratio device (Y waveguide) itself on a certain characteristic axis, reduce the number of spurious peaks while measuring, and improve the test accuracy of the high extinction ratio polarization device.

(4) In the process of measuring the high extinction ratio device (Y waveguide), there is no need to impose strict requirements on the measurement device, and the crosstalk can be quantitatively marked by using common devices such as polarization analyzer and polarization maintaining fiber, and the extinction ratio can be accurately measured , the construction of the whole device is simple, and the accuracy is significantly improved.

Description of drawings

Figure 1 is a schematic diagram of the optical principle of distributed polarization crosstalk measurement of a single defect point of an optical device;

Figure 2 is a schematic diagram of the corresponding relationship between the interference signal peak formed by single polarization crosstalk and the attenuation factor of transmitted light;

Figure 3 is a schematic diagram of beam changes when two polarization-maintaining fibers are aligned at the angle θ for welding;

Fig. 4 is a schematic diagram of a high extinction ratio measurement of an optical fiber polarization device;

Fig. 5 is a schematic diagram of measurement components for quantitative crosstalk labeling;

Fig. 6 is a flowchart of a method for measuring high extinction ratio of an optical fiber polarization device.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings.

The invention provides a method for measuring high extinction ratio of an optical fiber polarization device. Weld polarization-maintaining optical fibers with different lengths at the input and output ends of the high extinction ratio polarization device (Y waveguide) to be tested to form a measurement component with quantitative crosstalk marks; during welding, use a lumped extinction ratio tester to check the welding points Quantitatively control the extinction ratio and record its measurement value, and at the same time set the length of the pigtail fiber of the polarizer (analyzer), high extinction ratio polarization device (Y waveguide) and welding polarization-maintaining fiber; connect the above measurement components to In the distributed optical fiber polarization crosstalk test device, the extinction ratio of the polarization device to be tested is calibrated and self-calibrated by using the second-order crosstalk measurement value between the external optical fiber welding points, thereby improving the accuracy of the measurement. The invention has the advantages of high measurement precision and simple method, and is widely used in high-precision measurement and analysis of polarization properties of optical devices such as polarization-maintaining optical fibers and integrated waveguide modulators (Y waveguides).

The high extinction ratio measurement method of the optical fiber polarization device is to weld two sections of polarization maintaining optical fiber with different lengths at the input and output ends of the high extinction ratio polarization device (Y waveguide) to be tested to form a measurement component with a quantitative crosstalk mark; when welding Use the lumped extinction ratio tester to quantitatively control the extinction ratio of the welding point and record its measured value. At the same time, the pigtail of the polarizer (detector), the pigtail of the polarization device (Y waveguide) with high extinction ratio, and the welding polarization maintaining fiber The length is set; the measurement component is connected to the distributed optical fiber polarization crosstalk test device, and the extinction ratio of the polarization device to be tested is calibrated and self-calibrated by using the second-order crosstalk measurement value between the external optical fiber welding points. Measurement steps, including the selection and measurement of the input and output polarization maintaining fiber length and welding angle of the high extinction ratio polarization device (Y waveguide), the selection and measurement of the pigtail fiber length of the polarizer (analyzer), the measurement of distributed polarization crosstalk characteristics, and the high Calculation of the performance parameters of the extinction ratio polarization device (Y waveguide), the specific process is:

(1) Input the light beam from the input end y1 of the Y waveguide, and use the lumped extinction ratio tester to measure the crosstalk PER _c value at point C.

(2) Cut the length of the output end y2 of the Y waveguide as l ₃ , take the length of the polarization maintaining fiber 115 as l ₂ , use a polarization maintaining welding machine to align, and use a lumped extinction ratio tester for the output beam of the polarization maintaining fiber 115 Real-time measurement, the value of the measured extinction ratio at this time is PER _b +PER _c . Rotate the alignment angle to make the PER _b amount reach the set value (eg -30dB), at this time, weld the output end y2 of the Y waveguide to the polarization-maintaining optical fiber 115, and record the value PER _b at this time.

(3) The light beam is input from the polarization maintaining fiber 115, and the crosstalk PER _d value at point D is measured by a lumped extinction ratio tester.

(4) The length of the input end y1 of the Y waveguide is taken as l ₄ , the length of the polarization maintaining fiber 114 is taken as l ₅ , and the polarization maintaining welding machine is used to align the output beam of the polarization maintaining fiber 114 with a lumped extinction ratio tester Real-time measurement, the value of the measured extinction ratio at this time is PER _d +PER _e . Rotate the alignment angle to make the PER _b amount reach the set value (eg -45dB), at this time, weld the Y waveguide input end y1 to the polarization maintaining optical fiber 114, and record the value PER _e at this time.

(5) The lengths of the 45° polarizer PM pigtail ps1 and the 45° polarizer PM pigtail ps2 are intercepted as l ₆ and l ₁ , and the 45° polarizer PM fiber ps1 and the PM fiber 114 , 45° polarization analyzer polarization maintaining pigtail ps2 and polarization maintaining fiber 115 are aligned and welded at 0° to 0°.

(6) Connect the wide-spectrum light source and power monitoring device, optical path correlator, polarization crosstalk detection and signal recording device.

(7) Turn on the wide-spectrum light source, adjust the polarization state controller and the optical scanner to the maximum state of the interference signal. Drive the optical path scanner, use the polarization crosstalk detection and signal recording device to measure and record the data of different scanning distances in the optical path correlator, obtain the distributed polarization crosstalk measurement results, and record the polarization crosstalk noise floor in the measurement map Data with the position and magnitude of the individual interference peaks.

(8) Normalize the interferogram data, and compare the position and height of the first-order interference peaks on both sides of the main interference peak. According to the interception length l ₁ , l ₂ , l ₃ , l ₄ , l ₅ , l ₆ of the known optical fiber, use the relational formula:

τ=Δn _f l (1)

Get the ρ _A , ρ _B , ρ _C corresponding to the positions of τ _l1 , τ _l1 +τ _l2 , τ _l1 +τ _l2 +τ _l3 , τ _l4 +τ _l5 +τ _l6 , τ _l5 +τ _l6 , τ _l6 , ρ _D , ρ _E , and ρ _F peak amplitudes, and calibrated and self-calibrated the values of PER _b and ρ _B , PER _c and ρ _C , PER _d and ρ _D , PER _e and ρ _E , and obtained each first-order The exact values of the crosstalk peaks are shown in Table 1.

Table 1 The relationship between the first-order peak position and amplitude of the measurement components

(9) On the _basis of the _{first - order interference peak} , _{through calculation} , it can _{be obtained that} the ρ _A +ρ _D , ρ corresponding to the positions of +τ _l3 +τ _l4 +τ _l5 +τ _l6 , τ _l1 +τ _l2 +τ _l3 +τ _l5 +τ _l6 , τ _l1 +τ _l2 +τ _l3 +τ _l6 The peak size of _B +ρ _D , ρ _C +ρ _D , ρ _C +ρ _E , ρ _C +ρ _F is compared with the position and amplitude of the peaks in the spectrum, and the accurate value of each second-order crosstalk peak can be obtained. It is used for calibration and self-calibration of the high extinction ratio area, as shown in Table 2.

Table 2 The relationship between the second-order peak position and amplitude of the measurement components

(10) by measuring the peak amplitude at τ _l1 +τ _l2 +τ _l3 +τ _l4 +τ _l5 +τ _l6 +τ _lY (i.e. the outermost side of the interference pattern spectrum), the precise value of the extinction ratio of the Y waveguide to be tested is obtained, Complete accurate measurements, as shown in Table 3.

Table 3 The relationship between the position and amplitude of the Y-waveguide interference peak to be tested

45° polarizer polarization maintaining pigtail ps2, polarization maintaining fiber 115, output end y2 of Y waveguide 113, input end y1 of Y waveguide, polarization maintaining fiber 114, length _l1 of polarization maintaining pigtail ps1 of 45° polarizer, The selection of l ₂ , l ₃ , l ₄ , l ₅ and l ₆ must satisfy the following four aspects:

(1) When selecting the length, in order to prevent the interference judgment caused by peak overlap, it is necessary to satisfy the inequality relationship in formula (2), that is, to ensure that the corresponding first-order and second-order interference peaks in the interference spectrum are interlaced in the interference spectrum distributed:

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class="notranslate">\; \&NotEqual;</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; \&NotEqual;</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}\\ <span\; class="notranslate">\; \&NotEqual;</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; \&NotEqual;</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; \&NotEqual;</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}\\ <span\; class="notranslate">\; \&NotEqual;</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; \&NotEqual;</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}\\ <span\; class="notranslate">\; \&NotEqual;</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}\\ <span\; class="notranslate">\; \&NotEqual;</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; Y</span>}}\end{array}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

(2) The optical path difference of the input polarization-maintaining fiber length L _in of the Y waveguide is greater than the optical path L _r of the broadband light source ripple coherence peak, that is: L _in ×Δn _f >L _r (L _in is the input pigtail y1, The sum of the lengths of the polarization-maintaining fiber 114 and the 45° polarizer polarization-maintaining pigtail ps1, Δn _f is the linear birefringence of the polarization-maintaining fiber).

(3) The optical path difference of the output polarization-maintaining fiber length L _out of the Y waveguide is greater than the optical path difference between the fast and slow axes of the Y waveguide itself, that is: L _out ×Δn _f >L _Y ×Δn _Y (L _out is the output pigtail y2, the sum of the lengths of the polarization-maintaining fiber 115 and the polarization-maintaining pigtail ps2 of the 45° analyzer, LY is the length of the Y waveguide, and Δn _Y is the linear birefringence of the _Y waveguide).

(4) The measured optical path scanning range ΔL needs to meet

ΔL>2(L _in +L _Y +L _out ) (3)

Moreover, the midpoint of the optical path scanning range is selected as the position of the maximum peak value of the polarization crosstalk measurement data as much as possible.

For the angle alignment of points B and E, before the system test, the extinction ratio data of points C and D have been measured by the extinction ratio tester (according to the characteristics of the Y waveguide, generally around -40dB), it can be Set the extinction ratios of points B and E according to the size of points C and D, and use B, C, D, and E to form peak gradients for the first-order interference peaks and second-order interference peaks of the interference points. For example, the extinction ratios at points C and D are -37dB and -33dB respectively. At this time, PER _b = -30dB and PER _e = -45dB can be selected for points B and E during welding. In this way, the interference peak position and Correspondingly, there will be PER _b +PER _d = -63dB, PER _c +PER _d = -70dB, PER _c +PER _e = -82dB in the amplitude table, multiple high extinction ratio interference peaks with known positions and amplitudes are used for measuring devices of the calibration.

The invention is a calibration and measurement device for an optical coherent domain polarization test system (OCDP) based on the principle of white light interference. The working principle of OCDP is shown in Figure 1. Taking the performance test of the polarization-maintaining fiber as an example, the highly stable wide-spectrum polarized light 301 emitted by the wide-spectrum light source is injected into the slow axis of the polarization-maintaining fiber 321 of a certain length (at the time of the fast axis, same principle). Since not all light is transmitted strictly along the polarization-maintaining axis in a polarizing device, there will be non-ideal defect points or connections. When the signal light is transmitted along the slow axis, when the signal light is transmitted to the defect point 311, a part of the light energy in the slow axis will be coupled into the orthogonal fast axis to form a coupled beam 303, and the remaining transmitted beam 302 is still along the slow axis. shaft transmission. There is a linear birefringence Δn (for example: 5×10 ^-4 ) in the optical fiber, so that the refractive index of the slow axis is greater than the refractive index of the fast axis. When the other end of the fiber is output (the transmission distance is l), the transmitted light on the slow axis There will be an optical path difference Δnl between 302 and the coupled light 303 traveling on the fast axis. The above-mentioned light beam enters the optical path correlator 330 through the welding point or the rotary joint 312 . In the optical path correlator 330, a polarizing beam splitter 332, a fixed mirror 334, and a moving mirror 338 form a Michelson optical interferometer. The light beams 302 and 303 are divided into two parts in the fixed arm and the scanning arm by the optical path correlator 330 after passing through the polarization beam splitter 332 . The light transmitted in the fixed arm reaches the detector 339 after being reflected by the fixed mirror 334; the light transmitted in the scanning arm also reaches the detector 339 after being reflected by the moving mirror 338, and the two parts of light converge on the detector 339 to form white light Interfering with the signal, it receives and converts the optical signal into an electrical signal. After the signal is processed by the signal demodulation circuit 341, it is sent to the measurement computer 342; the measurement computer 342 is also responsible for controlling the moving mirror 338 to realize optical path scanning.

Under the control of the measurement computer 342, the moving mirror 338 of the Michelson interferometer makes the optical path difference of the two arms of the interferometer pass through zero from Δnl and scan to -Δnl, as shown in Figure 2:

(1) When the optical path difference is equal to Δnl, the light 204 in the scanning arm matches the light 201 in the fixed arm, and a white light interference signal is generated with a peak amplitude of It is proportional to the coupling magnitude factor of the defect point and the intensity of the light source.

(2) When the optical path difference is equal to 0, the light 205 and the light 201, the light 206 and the light 202 in the scanning arm and the fixed arm are matched, and a white light interference signal is generated, and its peak amplitude is I _coupling ∝ I ₀ , which is compatible with the light source Proportional to strength.

(3) When the optical path difference is equal to Δnl, the light 207 in the scanning arm is matched with the light 202 in the fixed arm, and a white light interference signal is generated with a peak amplitude of It is proportional to the coupling magnitude factor of the defect point and the intensity of the light source.

The interference signal is processed, normalized and converted into a dB value. By detecting the amplitude and distance of the interference peak, important information such as the position of the defect of the polarization-maintaining fiber and the extinction ratio can be obtained.

For the size of the structural calibration peak, the welding angle of the polarization-maintaining fiber can be adjusted. Figure 3. The polarized light transmitted by the fast axis in the incident polarization-maintaining fiber, as shown in Figure 3(a); when the alignment angle between the incident polarization-maintaining fiber and the exiting polarization-maintaining fiber is θ, the beam will generate components on the two characteristic axes of the exiting fiber , as shown in Figure 3(b); when the output polarization-maintaining fiber is transmitted, the ratio relationship between the two axes is tan ² θ, as shown in Figure 3(c). Equivalent to an extinction ratio of -10log ₁₀ [tan ² θ] (dB) constructed at the solder joint. Different "crosstalk" can be obtained by adjusting the alignment angle of the polarization-maintaining fiber, and different crosstalk peaks can be obtained by changing different alignment angles of the polarization-maintaining fiber.

From the interference diagram, the interference peaks on both sides of the main peak are formed by the interference of signal light and coupling light, and only one coupling light participates, so they are called first-order interference peaks. In this patent, the small extinction ratio (0-40dB) can be accurately marked by using the first-order interference peak. For the high extinction ratio (-40~-100dB) region, it is difficult to meet the calibration requirements for the angle accuracy of the polarization-maintaining fiber welding when directly aligning the angle. At this time, it is necessary to construct the second-order interference peak on the basis of the first-order interference peak. The second-order interference peak corresponds to a large extinction ratio, and its position and height are related to the length and alignment angle of the polarization-maintaining fiber forming the first-order interference peak. It is not necessary to make strict requirements on the alignment angle accuracy of the polarization-maintaining fiber, and the system Make precise marks. Under the premise of the existing alignment accuracy, the high-order interference peak can be used to complete the precise calibration of the small extinction ratio (-40dB ~ -100dB), and realize the calibration of the test system.

Taking Figure 5 as an example, in the measurement component of the quantitative crosstalk mark, there will be coupling of different characteristic axes for the light passing through each solder joint, and the number of couplings corresponds to the order of the crosstalk. Since the Y waveguide only allows the light of the fast axis to pass through, the light passing through the slow axis is excluded. For the first-order interference, that is, the interference formed by the 0-order beam (a straight-through beam without crosstalk) and the first-order crosstalk beam; for the second-order interference, it can be divided into two cases: (1) The 0-order beam and the second-order crosstalk beam form (2) The interference formed by the first-order crosstalk and the first-order crosstalk. For the case of first-order and second-order interference, the interference formula can be simplified as:

$\begin{array}{c}\frac{\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}\\ <span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}\\ <span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; Y</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; h</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; p</span>}}\\ <span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}\\ <span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}\\ <span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}\\ <span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}\\ <span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}\end{array}$

In the formula, R _x (τ) is the autocorrelation function, τ is the optical path delay of the two-arm beams in the optical path correlator, and ρ is the crosstalk coefficient of each solder joint, that is, corresponding to each peak in the spectrum, different optical path The amount of delay corresponds to the different coherence peaks, as shown in the Interference Peak Position and Amplitude table.

In addition, due to the characteristics of the high extinction ratio polarization device (Y waveguide) in the measurement component of the quantitative crosstalk mark, it can make full use of its uniaxial light transmission and extremely low crosstalk characteristics, and the high extinction ratio polarization device (Y waveguide) can be analyzed The one-axis light is effectively filtered to reduce the influence of redundant noise, obtain a clear and stable peak spectrum in the measurement area, and obtain extremely high measurement accuracy.

In order to clearly illustrate the high-order crosstalk-based OCDP white-light calibration device of the present invention, the present invention will be further described in conjunction with the embodiments and drawings, but this should not limit the protection scope of the present invention.

The high extinction ratio polarizing device measurement device is shown in Figure 4. The selection of main optoelectronic devices and their parameters are as follows:

(1) The central wavelength of the adjustable broadband light source 101 is 1550nm, the half-spectrum width is greater than 45°nm, the fiber output power range is 0-2mW, and the extinction ratio is greater than 6dB;

(2) The working wavelength of the 1×2 coupler 102 is 1550nm, the extinction ratio is greater than 20dB, the insertion loss is less than 0.5dB, and the splitting ratio is 2/98;

(3) The working wavelength of the optical fiber isolator 104 is 1550nm, the extinction ratio is 30dB, and the insertion loss is less than 1dB;

(4) The working wavelength of the 45° polarizer 111 is 1550nm, the extinction ratio is 30dB, the insertion loss is less than 1dB, the input end is a single-mode fiber, and the output is a panda-type polarization-maintaining fiber;

(5) The operating wavelength of the 45° polarizer 116 is 1550nm, the extinction ratio is 30dB, the insertion loss is less than 1dB, the input is a panda-type polarization-maintaining fiber, and the output is a single-mode fiber;

(6) The working wavelength of the 1×2 coupler 131 is 1550nm, the insertion loss is less than 0.5dB, and the splitting ratio is 50/50;

(7) The working wavelength of the polarization state controller 132 is 1550 nm, and the insertion loss is 0.5 dB;

(8) The working wavelength of the optical path scanner 133 is 1550nm, its optical path scanning distance varies between 0-400mm, and the average insertion loss is 3.0dB;

(9) The working wavelength of the 2×2 coupler 134 is 1550nm, and the insertion loss is less than 0.5dB;

(10) The photosensitive materials of the detectors 103, 135, and 136 are all InGaAs, and the light detection range is 1100-1700 nm, such as Nirvana ^TM series 2017 balanced detectors from New Focus.

(11) The measurement wavelength of the extinction ratio tester is 1260nm~1650nm, the range of polarization extinction ratio is 0~50dB, and the accuracy is ±0.3dB.

The working process of the high-precision polarization device measuring device is as follows:

Example 1: A high extinction ratio measurement method for an optical fiber polarization device

(1) The light beam is input from the input terminal y1 of the Y waveguide 113, and the crosstalk PER _c value at point C is measured.

(2) The light beam is input from the output terminal y2 of the Y waveguide 113, and the crosstalk PER _d value at point D is measured.

(3) The length of each section of polarization-maintaining optical fiber in the measurement component of quantitative crosstalk mark is selected, the polarization-maintaining optical fiber ps2 of 45 ° polarization analyzer 116, polarization-maintaining optical fiber 115, Y waveguide 113 output tail fiber y2, Y waveguide input tail Fiber y1, polarization maintaining fiber 114, and polarization maintaining fiber ps1 of 45° polarizer 111 are respectively set as: l ₁ =0.6m, l ₂ =0.6m, l ₃ =0.1m, l ₄ =0.2m, l ₅ =0.3m, l ₅ =0.6m.

(4) Align the output end y2 of the Y waveguide 113 with the polarization-maintaining fiber 115 using a polarization-maintaining welding machine, and measure the output beam of the polarization-maintaining fiber 115 in real time with an extinction ratio tester, and the value of the measured extinction ratio at this time is PER _b +PER _c . Rotate the alignment angle to make the PER _b amount reach the set value -30dB. At this time, weld the output end y2 of the Y waveguide 113 to the polarization-maintaining optical fiber 115, and record the value PER _b at this time.

(5) Align the output end y2 of the Y waveguide 113 with the polarization-maintaining fiber 114 using a polarization-maintaining welding machine, and measure the output beam from the polarization-maintaining fiber 114 in real time with an extinction ratio tester, and the value of the measured extinction ratio at this time is PER _d +PER _e , rotate the alignment angle, so that the PER _e value reaches the set value -45dB, at this time, weld the input end y1 of the Y waveguide 113 to the polarization-maintaining optical fiber 114, and record the value PER _e at this time.

(6) The 45° polarizer 111 polarization maintaining fiber ps1 and the polarization maintaining fiber 114 , the 45° polarization analyzer 111 the polarization maintaining pigtail ps2 and the polarization maintaining fiber 115 are aligned and welded at 0° to 0°.

(7) Connect the broadband light source with the power monitoring device 100 , the optical path correlator 120 , and the polarization crosstalk detection and signal recording device 130 .

(8) Turn on the wide-spectrum light source 101, and adjust the polarization state controller 132 and the optical scanner 133 to the maximum interference signal state. Drive the optical path scanner 133, use the polarization crosstalk detection and signal recording device 140 to measure and record the data of different scanning distances in the optical path correlator 130, obtain the distributed polarization crosstalk measurement results, and record the polarization crosstalk in the measurement map Noise floor data with the position and magnitude of individual interference peaks. (9) Normalize the interferogram data, and compare the position and height of the first-order interference peaks on both sides of the main interference peak. Get the ρ _A , ρ _B , ρ _C corresponding to the positions of τ _l1 , τ _l1 +τ _l2 , τ _l1 +τ _l2 +τ _l3 , τ _l4 +τ _l5 +τ _l6 , τ _l5 +τ _l6 , τ _l6 , ρ _D , ρ _E , and ρ _F peak amplitudes, and calibrated and self-calibrated the values of PER _b and ρ _B , PER _c and ρ _C , PER _d and ρ _D , PER _e and ρ _E , and obtained each first-order The exact numerical value of the crosstalk peak.

(10) Obtained in τ _l1 +τ _l4 +τ _l5 +τ _l6 , τ _l1 +τ _l2 +τ _l4 +τ _l5 +τ _l6 , τ _l1 +τ _l2 +τ _l3 +τ _l4 +τ _l5 +τ _l6 , ρ _A +ρ _D , ρ _B +ρ _D , ρ _C +ρ _D , ρ _C corresponding to the positions of τ _l1 +τ _l2 +τ _l3 +τ _l5 +τ _l6 , τ _l1 +τ _l2 +τ _l3 +τ _l6 The size of the +ρ _E , ρ _C +ρ _F peaks are compared with the peak position and amplitude in the spectrum, and the precise value of each second-order crosstalk peak can be obtained, which is used for calibration and self-calibration of the high extinction ratio area.

(10) by measuring the peak amplitude at τ _l1 +τ _l2 +τ _l3 +τ _l4 +τ _l5 +τ _l6 +τ _lY (i.e. the outermost side of the interference pattern spectrum), the precise value of the extinction ratio of the Y waveguide to be tested is obtained, Accurate measurements are done.

Claims (2)

1. A high extinction ratio measurement method of an optical fiber polarization device, in which two sections of polarization-maintaining optical fiber with different lengths are respectively welded at the input and output ends of the high extinction ratio polarization device to be measured, that is, the Y waveguide, to form a measurement assembly with a quantitative crosstalk mark ; When welding, use the lumped extinction ratio tester to quantitatively control the extinction ratio of the welding point and record its measured value. The length of the polarization optical fiber is set; the measurement component is connected to the distributed optical fiber polarization crosstalk test device, and the second-order crosstalk measurement value between the welding points of the external optical fiber is used to calibrate and self-calibrate the extinction ratio of the polarization device to be measured; it is characterized in that , including the following steps: (1) Input the light beam from the input end (y1) of the Y waveguide (113), and use the lumped extinction ratio tester to measure the C-point crosstalk PER _c value; (2) Take the length of the output end (y2) of the Y waveguide (113) as l ₃ , take the length of the polarization-maintaining fiber (115) as l ₂ , use a polarization-maintaining welding machine to align, and the output of the polarization-maintaining fiber (115) The light beam is measured in real time with a lumped extinction ratio tester, and the value of the measured extinction ratio is PER _b +PER _c ; rotate the alignment angle so that the amount of PER _b reaches the set value, and the Y waveguide (113) output terminal (y2) Weld with the polarization maintaining optical fiber (115), and record the value PER _b at this time; (3) input the beam from the polarization-maintaining fiber (115), and use the lumped extinction ratio tester to measure the D-point crosstalk PER _d value; ( ₄ ) The length of the input end (y1) of the Y waveguide (113) is taken as l4, the length of the polarization-maintaining fiber (114) is taken as l5, aligned with a polarization _- maintaining welding machine, and the output of the polarization-maintaining fiber (114) The light beam is measured in real time with a lumped extinction ratio tester, and the value of the measured extinction ratio is PER _d +PER _e ; rotate the alignment angle so that the amount of PER _b reaches the set value, and the Y waveguide (113) input terminal (y1) Weld with the polarization maintaining fiber (114), and record the value PER _e at this time. (5) Cut the lengths of the 45° polarizer (111) polarization-maintaining pigtail (ps1) and the 45° analyzer (116) polarization-maintaining pigtail (ps2) as l ₆ , l ₁ , and the 45° polarizer The polarization-maintaining optical fiber (ps1) of the detector (111) and the polarization-maintaining optical fiber (114), the polarization-maintaining pigtail (ps2) of the 45° polarization analyzer (111) and the polarization-maintaining optical fiber (115) are all aligned and welded at 0° to 0°; (6) Connect the wide-spectrum light source and the power monitoring device (100), the optical path correlator (130), the polarization crosstalk detection and signal recording device (140); (7) Turn on the wide-spectrum light source (101), adjust the polarization state controller (132) and the optical scanner (133) to the maximum state of the interference signal, drive the optical path scanner (133), and use the polarization crosstalk detection and signal recording device ( 140) Measure and record the data of different scanning distances in the optical path correlator (130), obtain the distributed polarization crosstalk measurement results, and record the polarization crosstalk noise background data and the positions and amplitudes of each interference peak in the measurement spectrum ; (8) Normalize the interferogram data, and compare the position and height of the first-order interference peaks on both sides of the main interference peak; according to the known interception lengths l ₁ , l ₂ , l ₃ , l ₄ , l ₅ , l ₆ , using the relational expression: τ=Δn _f l Get the ρ _A , ρ _B , ρ _C corresponding to the positions of τ _l1 , τ _l1 +τ _l2 , τ _l1 +τ _l2 +τ _l3 , τ _l4 +τ _l5 +τ _l6 , τ _l5 +τ _l6 , τ _l6 , ρ _D , ρ _E , and ρ _F peak amplitudes, and calibrated and self-calibrated the values of PER _b and ρ _B , PER _c and ρ _C , PER _d and ρ _D , PER _e and ρ _E , and obtained each first-order exact value of the crosstalk peak; The optical path delay is 0, The crosstalk coefficients are 1, ρ _A , ρ _B , ρ _C , ρ _D , ρ _E , ρ _F ; (9) On the basis of the first-order interference peak, through calculation, it is obtained that τ _l1 +τ _l4 +τ _l5 +τ _l6 , τ _l1 +τ _l2 +τ _l4 +τ _l5 +τ _l6 , τ _l1 +τ _l2 + ρ _A + ρ _D , ρ _B corresponding to the positions of τ _l3 +τ _l4 +τ _l5 +τ _l6 , τ _l1 +τ _l2 +τ _l3 +τ _l5 +τ _l6 , τ _l1 +τ _l2 +τ _l3 +τ _l6 +ρ _D , ρ _C +ρ _D , ρ _C +ρ _E , ρ _C +ρ _F peak size are compared with the peak position and amplitude in the spectrum to obtain the exact value of each second-order crosstalk peak, which is used for Calibration and self-calibration of the high extinction ratio area; the optical path delay is The crosstalk coefficients are ρ _A + ρ _D , ρ _B + ρ _D , ρ _C + ρ _D , ρ _C + ρ _E , ρ _C + ρ _F ; (10) By measuring the peak amplitude at τ _l1 +τ _l2 +τ _l3 +τ _l4 +τ _l5 +τ _l6 +τ _lY , which is the outermost part of the interference pattern, the precise value of the extinction ratio of the Y waveguide to be measured is obtained, and the precise Measurement, Optical Path Retardation The crosstalk coefficient of ε _chip . 2. the high extinction ratio measuring method of a kind of optical fiber polarization device according to claim 1, is characterized in that: described 45 ° polarizer (116) polarization-maintaining pigtail (ps2), polarization-maintaining fiber (115) , Y waveguide (113) output end (y2), the input end (y1) of Y waveguide (113), the length l ₁ of polarization maintaining fiber (114), 45 ° polarizer (111) polarization maintaining pigtail (ps1) , l ₂ , l ₃ , l ₄ , l ₅ , and l ₆ are selected to satisfy the relations in four aspects: 1) Ensure that the corresponding first-order and second-order interference peaks in the interferogram are staggered in the interferogram: l ₁ ≠l ₆ ≠l ₁ +l ₂ ≠l ₅ +l ₆ ≠l ₁ +l ₆ ≠l ₁ +l ₂ +l ₃ ≠l ₁ +l ₂ +l ₆ ≠l ₁ +l ₅ +l ₆ ≠l ₄ +l ₅ +l ₆ ≠l ₁ +l ₄ +l ₅ +l ₆ ≠l ₁ +l ₂ +l ₃ +l ₆ ≠l ₁ +l ₂ +l ₅ +l ₆ ; ≠l ₁ +l ₂ +l ₄ +l ₅ +l ₆ ≠l ₁ +l ₂ +l ₃ +l ₅ +l ₆ ≠l ₁ +l ₂ +l ₃ +l ₄ +l ₅ +l ₆ ≠l ₁ +l ₂ +l ₃ +l ₄ +l ₅ +l ₆ +l _Y 2) The optical path difference of the length L _in of the input polarization-maintaining fiber (y1) of the Y waveguide (113) is greater than the optical path L _r of the ripple coherence peak of the broadband light source (101), namely: _Lin ×Δn _f >L _r , L _in is the sum of the lengths of input pigtail y1, PM fiber 114, and 45° polarizer PM pigtail ps1, Δn _f is the linear birefringence of PM fiber; 3) The optical path difference of the output polarization maintaining fiber (y2) length L _out of the Y waveguide (113) is greater than the optical path difference between the fast and slow axes of the Y waveguide (113), namely: L _out ×Δn _f >L _Y ×Δn _Y ; L _out is the sum of output pigtail y2, polarization-maintaining fiber 115, and 45° polarizer polarization-maintaining pigtail ps2 length; L _Y is the length of the Y waveguide, and Δn _Y is the linear birefringence of the Y waveguide; 4) Measured optical path scanning range ΔL ΔL>2(L _in +L _Y +L _out ) The midpoint of the optical path scanning range is the position of the maximum peak value of the polarization crosstalk measurement data.