CN116086628A - Faraday sheet center wavelength measurement system - Google Patents

Abstract

The invention discloses a Faraday sheet center wavelength measurement system, which comprises a light source, a light path switching system, a Faraday test system and an OSA system, wherein the light path switching system is used for controlling whether a light path between the light source and the OSA system passes through the Faraday test system first; the Faraday test system comprises a polarization/analyzer, a Faraday rotator and a deflection reflection device; the OSA system collects optical signals input through two different optical paths, compares the light intensity distribution conditions of the two optical signals with different wavelengths, and can directly determine the center wavelength of a Faraday plate in the Faraday rotator, namely the center wavelength corresponding to 45 degrees of rotation. The system can realize accurate and automatic measurement of the Faraday center wavelength, a measurer can directly read the Faraday center wavelength by only putting the Faraday sheet in, the placement angle is not required, the automatic introduction can be facilitated, and the system is an efficient, quick and direct Faraday center wavelength measurement system.

Description

Faraday sheet center wavelength measurement system

Technical Field

The invention relates to a Faraday plate center wavelength measurement system.

Background

The traditional mode of measuring the center wavelength of the Faraday plate in the industry is an indirect measurement mode, and is obtained by measuring the rotation angles under different point wavelengths through a rotation angle test system shown in figure 1 and then converting according to the wavelength correlation coefficient of the Faraday material. In fig. 1, 1 is a single-mode fiber collimator (SM fiber Collimator), 2 is a Polarizer (Polarizer), 3 is a faraday rotator, 4 is an Analyzer, and 5 is an optical Power meter (Power meter).

The defects are that: (1) two angle data are read by manually rotating the analyzer, and a person has errors in reading the angle scales on the analyzer; (2) through the test, only the rotation angle under the specific wavelength can be obtained, 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 parameters of the Faraday materials.

Disclosure of Invention

The invention aims to provide a measuring system capable of accurately, quickly and directly measuring the center wavelength of a Faraday plate.

The invention realizes the aim of the invention through the following technical scheme: the Faraday sheet center wavelength measurement system comprises a light source, a light path switching system, a Faraday test system and an OSA system, wherein the light path switching system is used for controlling whether a light path between the light source and the OSA (optical spectrum analyzer) system passes through the Faraday test system first;

the Faraday test system comprises a polarization/analyzer, a Faraday rotator and a deflection reflection device, wherein incident light enters the polarization/analyzer to be polarized, then passes through the Faraday rotator to rotate the polarization state, then passes through the deflection reflection device to output a path of reflected light parallel to the incident light of the deflection reflection device, and passes through the Faraday rotator to continuously rotate the polarization state, and then passes through the polarization/analyzer to output the Faraday test system;

the OSA system collects optical signals input through two different optical paths (the Faraday test system is connected with the Faraday test system and the Faraday test system is not connected with the Faraday test system), and the central wavelength of a Faraday sheet in the Faraday rotator, namely the central wavelength corresponding to 45 degrees of rotation, can be directly determined by comparing the light intensity distribution conditions of the two optical signals with different wavelengths.

The optical path switching system is composed of a pair of reflecting mirrors, the two reflecting mirrors are arranged in an eight shape, the optical path switching system is integrally rotatably arranged between the light source and the OSA system, when the optical path switching system rotates to a position A, the light source directly outputs to the 0SA system, when the optical path switching system rotates to a position B, output light of the light source is reflected by one side of the reflecting mirrors and then is vertically output to the Faraday testing system with incident light, and output light of the Faraday testing system is reflected by the other side of the reflecting mirrors and then is vertically output to the 0SA system with the incident light.

The deflection reflecting device adopts a pyramid prism.

The polarization/analyzer adopts PBS cube.

The light source adopts an LED light source.

The OSA system adopts a spectrum analyzer consisting of a collimating mirror, a grating, a condensing mirror and a CCD array detector.

The Faraday rotator consists of a Faraday plate, a Faraday plate bracket and a magnetic ring;

the Faraday sheet support comprises a circular sleeve which is used for being inserted into the inner side of the magnetic ring in an adaptive mode, the end face of one end of the sleeve extends outwards to form an end sheet with larger size, a sleeve barrel cavity axially penetrates through the whole sleeve, one end, far away from the end sheet, of the sleeve barrel cavity is a slide way which is matched with the Faraday sheet, an inner annular shoulder is formed at the bottom end of the slide way to support the Faraday sheet, an axial split notch is formed in the side wall of the slide way, and the split notch extends from the top end of the slide way to the bottom end of the slide way.

The beneficial effects are that:

1) The OSA system collects the optical signals input through two different optical paths, performs difference calculation on the optical signals, namely, the center wavelength of the Faraday plate can be determined according to the peak point of the light intensity distribution curve of the optical signals with different wavelengths;

2) The invention can directly read out the center wavelength data of the Faraday plate from the OSA system without any data processing process;

3) When the central wavelength of the Faraday plate is measured by the invention, a measurer only needs to put the Faraday plate in order to enable the OSA system to collect data of two light paths, and the central wavelength can be directly read out, so that the operation is simple and efficient.

Drawings

Fig. 1 is a schematic diagram of a conventional faraday rotation angle test system;

fig. 2 is a schematic diagram of a faraday-plate center wavelength measurement system according to a preferred embodiment of the present invention;

FIG. 3 is an example wavelength dependence graph of an OSA system output;

fig. 4 is a schematic structural view of a faraday plate holder according to the present embodiment.

Detailed Description

The structure of the faraday center wavelength measurement system of the present embodiment is shown in fig. 2, and the broadband light source (LED sources), the optical path switching system (Optical Switch System) Part1, the faraday test system (Faraday Test System) Part2, and the OSA system (Optical Spectrum Analyzer System) Part3 are sequentially arranged from left to right.

Broadband light source (LED sources): as a light source for emitting broadband signal light to the system.

An optical path switching system (Optical Switch System) Part1: consists of a pair of reflecting mirrors and is used for controlling whether Part2 participates in the optical path. When Part1 is switched to the outside of the optical path, part2 does not participate in the processing of the whole optical path, at the moment, signal light emitted by the LED light source directly enters an OSA system Part3, and background signals are recorded as references;

when Part1 is switched into the optical path, part2 also participates in the optical path, and the signal light emitted by the LED light source enters the OSA system Part3 after passing through Part1 and Part2, and the test signal is recorded to be compared with the background signal.

The Faraday test system (Faraday Test System) Part2 consists of a PBS cube (polarization/polarization-detecting system), an optical rotator consisting of a magnetic ring and a Faraday plate FR, and a pyramid prism. The magnetic field strength of the magnetic ring is more than 1000 oe.

The test principle is as follows: the broadband signal light enters the PBS cube and is polarized, the polarization state of the broadband signal light rotates after passing through the Faraday sheet to be detected, the broadband signal light is reflected after being deflected by the pyramid prism, the polarization state of the broadband signal light continues to rotate after passing through the Faraday sheet again, and finally the broadband signal light is output from the other end of the Part1 reflector pair and enters the OSA system Part3.

The OSA system Part3 adopts an industry standard spectrum analyzer and consists of a collimating lens, a grating, a condensing lens and a CCD (charge coupled device), and is used for recording the light intensity distribution conditions of different wavelengths, namely directly outputting the dependence curve of the insertion loss IL of the Faraday to be detected along with the wavelength.

Since the rotation angle of faraday has wavelength dependence, that is, the rotation angle of the part deviating from the center wavelength is no longer 45 °, the loss of the wavelength part passing through PBS cube (polarization/polarization-detecting system) will change, resulting in wavelength dependence of the test signal. The wavelength corresponding to the peak point of the curve can be obtained according to the curve output on the display of the OSA system, namely the center wavelength data corresponding to the Faraday rotation angle to be measured under the condition of 45 degrees. As shown in fig. 3, the peak position of the loss is the center wavelength position corresponding to the rotation angle of 45 °. Fig. 3 shows test data around 1550nm, and below 1064nm, which are the two most common bands in the industry.

The measurement accuracy of the system is determined by ER performance of PBS cube (polarization/polarization-maintaining system), interference of human factors is completely eliminated, and compared with the traditional test method, the system has higher accuracy.

In this embodiment, the optical rotator includes a magnetic ring and a faraday plate FR, and a faraday plate holder is provided for facilitating the installation of the faraday plate FR. Figure 4 is a view of a faraday plate holder. Wherein, the left side is a rear view, the middle is a side view, and the right side is a front view. As shown, the faraday support comprises a circular sleeve 51 for being inserted into the inner side of the magnetic ring in an adapting manner, one end face of one end of the sleeve 51 extends outwards to form an end piece 52 with a larger size, the sleeve barrel axially penetrates through the whole sleeve, one end of the barrel away from the end piece 52 is a slideway 511 adapted with the faraday piece FR, an inner annular shoulder 512 is formed at the bottom end of the slideway 511 to support the faraday piece FR, an axial cut-out 513 is formed on the side wall of the slideway 511, and the cut-out extends from the top end of the slideway 511 to the bottom end of the slideway 511, so that the faraday piece FR can be directly placed on the inner annular shoulder 512 by operating tweezers or the like at the cut-out.

The system can realize the accurate measurement of the center wavelength of the Faraday plate, and the measuring staff only needs to put the Faraday plate in order to directly read the center wavelength, so that the system has no requirement on the placement angle of the Faraday plate, is beneficial to automatic introduction, and is an efficient, quick and direct Faraday plate center wavelength measuring system.

Claims (7)

1. The Faraday sheet center wavelength measurement system is characterized by comprising a light source, an optical path switching system, a Faraday test system and an OSA system, wherein the optical path switching system is used for controlling whether an optical path between the light source and the OSA system passes through the Faraday test system first;

the Faraday test system comprises a polarization/analyzer, a Faraday rotator and a deflection reflection device, wherein incident light enters the polarization/analyzer to be polarized, then passes through the Faraday rotator to rotate the polarization state, then passes through the deflection reflection device to output a path of reflected light parallel to the incident light of the deflection reflection device, and passes through the Faraday rotator to continuously rotate the polarization state, and then passes through the polarization/analyzer to output the Faraday test system;

the OSA system collects optical signals input through two different optical paths, compares the light intensity distribution conditions of the two optical signals with different wavelengths, and can directly determine the center wavelength of a Faraday plate in the Faraday rotator, namely the center wavelength corresponding to 45 degrees of rotation.

2. The system according to claim 1, wherein the optical path switching system is composed of a pair of mirrors, the mirrors are arranged in an "eight" shape, and are integrally rotatably mounted between the light source and the OSA system, when the light source rotates to the position a, the light source directly outputs to the OSA system, when the light source rotates to the position B, the output light of the light source is reflected by one mirror and then outputted to the faraday testing system perpendicular to the incident light, and the output light of the faraday testing system is reflected by the other mirror and then outputted to the 0SA system perpendicular to the incident light.

3. A faraday plate center wavelength measurement system according to claim 1, characterized in that the deflection reflecting means is a corner cube.

4. A faraday plate center wavelength measurement system according to claim 1, wherein the polarizing/analyzer employs a PBS cube.

5. A faraday plate center wavelength measurement system according to claim 1, characterized in that the light source is an LED light source.

6. The faraday plate center wavelength measurement system of claim 1, wherein the OSA system employs a spectrum analyzer consisting of a collimator lens, a grating, a condenser lens, a CCD array detector.

7. The faraday plate center wavelength measurement system of claim 1, wherein the faraday rotator is comprised of a faraday plate, a faraday plate holder, and a magnetic ring;

the Faraday sheet support comprises a circular sleeve which is used for being inserted into the inner side of the magnetic ring in an adaptive mode, the end face of one end of the sleeve extends outwards to form an end sheet with larger size, a sleeve barrel cavity axially penetrates through the whole sleeve, one end, far away from the end sheet, of the sleeve barrel cavity is a slide way which is matched with the Faraday sheet, an inner annular shoulder is formed at the bottom end of the slide way to support the Faraday sheet, an axial split notch is formed in the side wall of the slide way, and the split notch extends from the top end of the slide way to the bottom end of the slide way.

Images