A faraday sheet center wavelength measurement system

Abstract

The application discloses a Faraday disc center wavelength measurement system, which comprises a light source, an optical path switching system, a Faraday test system and an OSA system, the optical path switching system is used for controlling whether the optical path between the light source and the OSA system passes through the Faraday test system first, the Faraday test system comprises a polarizer / analyzer, a Faraday rotator and a deflection reflection device, the OSA system collects light signals input through two different optical paths, compares the light intensity distribution of the two light signals at different wavelengths, and directly determines the center wavelength of the Faraday disc in the Faraday rotator, that is, the center wavelength corresponding to the rotation of 45 degrees. The system can realize the accurate and automatic measurement of the Faraday center wavelength, the center wavelength can be directly read out by only placing the Faraday disc, and there is no requirement for the placement angle, so that the system can be beneficially introduced into automation, and is a high-efficiency, quick and direct Faraday center wavelength measurement system.

Description

TECHNICAL FIELD

[0001] The application relates to a Faraday disc center wavelength measurement system. BACKGROUND

[0002] The traditional industry measurement method for the center wavelength of a Faraday disc is an indirect measurement method. Figure 1 As shown in a rotation angle test system, the rotation angle at different wavelengths is measured, and then the center wavelength corresponding to the Faraday rotation of 45 degrees is obtained through conversion according to the wavelength correlation coefficient of the Faraday material. Figure 1 In the figure, 1 is a single-mode fiber collimator (SM fiber Collimator), 2 is a polarizer, 3 is a Faraday rotator, 4 is an analyzer, and 5 is a power meter.

[0003] Disadvantages are as follows: ① Two angle data are read by manually rotating the analyzer, and there is an error in reading the angle scale on the analyzer by personnel; ② Only the rotation angle at a specific wavelength can be obtained through the test, but the center wavelength data corresponding to the Faraday rotation of 45 degrees cannot be directly obtained, and the center wavelength data corresponding to the Faraday rotation of 45 degrees needs to be indirectly converted according to the wavelength correlation parameter of the Faraday material. SUMMARY

[0004] The application aims to provide a measurement system capable of accurately, quickly and directly measuring the center wavelength of a Faraday disc.

[0005] The application achieves the application purpose through the following technical scheme: a Faraday disc center wavelength measurement system comprises a light source, an optical path switching system, a Faraday test system and an OSA system, the optical path switching system is used for controlling whether the optical path between the light source and the OSA (optical spectrum analyzer) system passes through the Faraday test system first;

[0006] The Faraday test system comprises a polarizer / analyzer, a Faraday rotator and a deflection reflection device, incident light first enters the polarizer / analyzer to be polarized, then passes through the Faraday rotator to make the polarization state rotate, and then passes through the deflection reflection device to output reflected light parallel to the incident light of the deflection reflection device, the reflected light passes through the Faraday rotator again to make the polarization state continue to rotate, and then the Faraday test system is output through the polarizer / analyzer.

[0007] The OSA system collects optical signals input through two different optical paths (accessing the Faraday test system and not accessing the Faraday test system), compares the light intensity distribution of the two optical signals at different wavelengths, and directly determines the center wavelength of the Faraday disc in the Faraday rotator, i.e., the center wavelength corresponding to the rotation of 45 degrees.

[0008] The light path switching system is composed of a pair of mirrors arranged in a "figure of eight" and integrally rotatably installed between the light source and the OSA system, when the mirrors are rotated to position A, the light source directly outputs to the OSA system, when the mirrors are rotated to position B, the output light of the light source is reflected by one of the mirrors and then output perpendicularly to the incident light to the Faraday test system, the output light of the Faraday test system is reflected by the other mirror and then output perpendicularly to the incident light to the OSA system.

[0009] The deflection reflection device adopts an angular pyramid prism.

[0010] The polarizer / analyzer adopts a PBS cube.

[0011] The light source adopts an LED light source.

[0012] The OSA system adopts a spectrum analyzer composed of a collimating mirror, a grating, a condensing mirror and a CCD array detector.

[0013] The Faraday optical rotator is composed of a Faraday sheet, a Faraday sheet support and a magnetic ring.

[0014] The Faraday sheet support comprises a circular sleeve for being inserted into the inside of the magnetic ring, the sleeve extends outward at one end to form a larger end piece, the sleeve cavity axially penetrates through the whole sleeve, the end of the sleeve cavity away from the end piece is a slide adapted to the Faraday sheet, the bottom end of the slide forms an inner ring shoulder to support the Faraday sheet, and the side wall of the slide is provided with an axial cutout extending from the top end of the slide to the bottom end of the slide.

[0015] Advantages:

[0016] 1) The OSA system collects the light signals input through two different light paths, and performs difference operation on them, so that the central wavelength of the Faraday sheet can be determined according to the peak points of the light intensity distribution curves of different wavelengths of the light signals, the accuracy of the measurement data of the present application is determined by the ER (polarization extinction ratio) performance of the optical device and is not disturbed by human factors, and the accuracy is higher than that of the traditional test method;

[0017] 2) The present application does not need any data processing process, and the central wavelength data of the Faraday sheet can be directly read out from the OSA system;

[0018] 3) When the central wavelength of the Faraday sheet is measured by the present application, the measurement personnel only need to put in the Faraday sheet, let the OSA system collect the data of the two light paths, and the central wavelength can be directly read out, which is simple and efficient. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1It is a schematic diagram of the principle of a traditional Faraday rotation angle test system;

[0020] Figure 2 It is a schematic diagram of the principle of a Faraday disc center wavelength measurement system of a preferred embodiment of the present application;

[0021] Figure 3 It is an example of a wavelength correlation diagram output by an OSA system;

[0022] Figure 4 It is a structural schematic diagram of a Faraday disc holder of the present embodiment. DETAILED DESCRIPTION

[0023] The structure of the Faraday disc center wavelength measurement system of the present embodiment is shown in Figure 2 from left to right, which are wideband light sources (LED sources), an optical switch system (Optical Switch System) Part 1, a Faraday test system (Faraday Test System) Part 2, and an OSA system (Optical Spectrum Analyzer System) Part 3.

[0024] Wideband light sources (LED sources): as light sources, used to emit wideband signal light to the system.

[0025] Optical switch system (Optical Switch System) Part 1: composed of a pair of mirrors, used to control whether Part 2 participates in the optical path. When Part 1 itself is switched out of the optical path, Part 2 does not participate in the processing of the entire optical path, at this time, the signal light emitted by the LED light source directly enters the OSA system Part 3, and the background signal is recorded as a reference;

[0026] When Part 1 is switched into the optical path, Part 2 also participates in the optical path, and the signal light emitted by the LED light source enters the OSA system Part 3 after passing through Part 1 and Part 2, and the test signal is recorded for comparison with the background signal.

[0027] The Faraday test system (Faraday Test System) Part 2 is composed of a PBS cube (polarization / analysis system), a rotator composed of a magnetic ring and a Faraday disc FR, and a corner cube prism. The magnetic field strength of the magnetic ring is greater than 1000oe.

[0028] The test principle is: after the wideband signal light enters the PBS cube, it is polarized, the polarization state is rotated after passing through the Faraday disc to be tested, and after being deflected by the corner cube prism, it is reflected again, and the polarization state continues to rotate after passing through the Faraday disc again, and finally output from the other end of the Part 1 mirror pair into the OSA system Part 3.

[0029] The OSA system Part 3 adopts an industry standard spectrum analyzer, which is composed of a collimating mirror, a grating, a condenser and a CCD, and is used for recording the light intensity distribution of different wavelengths, i.e. directly outputting the dependence curve of the insertion loss IL of the measured Faraday on the wavelength.

[0030] Since the rotation angle of the Faraday has wavelength dependence, i.e. the rotation angle deviating from the central wavelength is no longer 45°, the loss of the wavelength part passing through the PBS cube (polarization / analysis system) before and after will change, resulting in the wavelength dependence of the test signal. According to the curve output on the display of the OSA system, it can be obtained that the wavelength corresponding to the peak point of the curve is the central wavelength data corresponding to the Faraday rotation angle of 45° under the condition. As shown in Figure 3 , the peak position of the loss is the central wavelength position corresponding to the rotation angle of 45°. Figure 3 The upper is the test data near 1550nm, and the lower is the test data near 1064nm. These two wave bands are the most commonly used wave bands in the industry.

[0031] The measurement accuracy of the system is determined by the ER performance of the PBS cube (polarization / analysis system), completely eliminating the interference of human factors, and the accuracy is higher than that of the traditional test method.

[0032] In addition to the magnetic ring and the Faraday sheet FR, the optical rotator of the embodiment is also provided with a Faraday sheet support for facilitating the installation of the Faraday sheet FR. Figure 4 The left side is a rear view, the middle is a side view, and the right side is a front view. As shown in the figure, the Faraday sheet support includes a circular sleeve 51 adapted to be inserted into the inside of the magnetic ring, the end face of the sleeve 51 extends outward to form a larger end piece 52, the sleeve cavity axially penetrates through the entire sleeve, the end of the sleeve cavity away from the end piece 52 is a sliding channel 511 adapted to the Faraday sheet FR, the bottom end of the sliding channel 511 forms an inner ring shoulder 512 to support the Faraday sheet FR, and the side wall of the sliding channel 511 is provided with an axial cut 513 extending from the top end of the sliding channel 511 to the bottom end of the sliding channel 511, so that the Faraday sheet FR can be directly placed on the inner ring shoulder 512 by operating a pair of tweezers or the like at the cut.

[0033] The system can realize accurate measurement of the central wavelength of the Faraday sheet, and the measurement personnel only need to put in the Faraday sheet, and the central wavelength can be directly read out, without any requirement for the placement angle of the Faraday sheet, which is conducive to automatic import and is a high-efficiency, fast and direct Faraday sheet central wavelength measurement system.

Claims

1. A Faraday disk center wavelength measurement system, characterized by, The system comprises a light source, an optical path switching system, a Faraday testing system and an OSA system, the optical path switching system is used to control whether the light path between the light source and the OSA system passes through the Faraday testing system first; The Faraday testing system comprises a polarizer / analyzer, a Faraday rotator and a deviating reflector, the incident light first enters the polarizer / analyzer to be polarized, then passes through the Faraday rotator to rotate the polarization state, and then passes through the deviating reflector to output a reflected light parallel to the incident light of the deviating reflector, the reflected light passes through the Faraday rotator again to continue rotating the polarization state, and then passes through the polarizer / analyzer to output the Faraday testing system; The OSA system collects the light signals input through two different light paths, compares the light intensity distribution of the two light signals at different wavelengths, and directly determines the center wavelength of the Faraday sheet in the Faraday rotator, i.e., the center wavelength corresponding to a 45° rotation.

2. The Faraday disc center wavelength measurement system of claim 1, wherein, The optical path switching system comprises a pair of mirrors arranged in a "figure of eight" and integrally installed between the light source and the OSA system, when the optical path switching system is rotated to position A, the light source directly outputs to the OSA system, when the optical path switching system is rotated to position B, the output light of the light source is reflected by one of the mirrors and output to the Faraday testing system perpendicularly to the incident light, i.e., the output light of the light source, the output light of the Faraday testing system is reflected by the other mirror and output to the OSA system perpendicularly to the incident light, i.e., the output light of the Faraday testing system.

3. The Faraday disk center wavelength measurement system of claim 1, wherein, The deviating reflector adopts an angle pyramid prism.

4. The Faraday disk center wavelength measurement system of claim 1, wherein, The polarizer / analyzer adopts a PBS cube.

5. The Faraday disk center wavelength measurement system of claim 1, wherein, The light source adopts an LED light source.

6. The Faraday disk center wavelength measurement system of claim 1, wherein, The OSA system adopts a spectrum analyzer comprising a collimating mirror, a grating, a condensing mirror and a CCD array detector.

7. The Faraday disk center wavelength measurement system of claim 1, wherein, The Faraday rotator comprises a Faraday sheet, a Faraday sheet support and a magnetic ring; The Faraday sheet support comprises a circular sleeve adapted to be inserted into the inside of the magnetic ring, one end of the sleeve extends outward to form a larger end piece, the sleeve cavity axially penetrates through the entire sleeve, the end of the sleeve cavity away from the end piece is a slide adapted to the Faraday sheet, the bottom end of the slide forms an inner ring shoulder to support the Faraday sheet, the side wall of the slide is provided with an axial cutout extending from the top end of the slide to the bottom end of the slide.

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