Testing tool and testing platform for magneto-optical performance of Faraday rotating sheet

Abstract

The utility model belongs to the field of magneto-optical material performance testing, and particularly discloses a testing tool and a testing platform for magneto-optical performance of a Faraday rotating piece, the testing tool comprises a base, a light inlet plate, a light outlet plate, a sample clamp and two magnets, the light inlet plate and the light outlet plate are arranged on the base, a gap is reserved between the light inlet plate and the light outlet plate, and semi-closed magnet grooves are formed in the light inlet plate and the light outlet plate; the groove bottom of the magnet groove serves as a limiting plate and is arranged on the side close to the gap, and a first light through hole is formed in the center of the limiting plate. The sample clamp is arranged in a gap between the light inlet plate and the light outlet plate, and a second light through hole is formed in the center of the sample clamp; the two magnets are inserted into the magnet grooves respectively, the magnet grooves are limited through the limiting plates, and third light through holes are formed in the centers of the magnets. The Faraday rotating piece can be magnetized to reduce scattered light, the length of the tool parallel to the light passing direction is effectively reduced, and therefore the test error caused by scattering is reduced by reducing the scattered light and improving the scattered light receiving rate.

Description

Technical Field

[0001] This application belongs to the field of magneto-optical material performance testing, and more specifically, relates to a testing fixture and testing platform for the magneto-optical performance of a Faraday rotatable sheet. Background Technology

[0002] Faraday rotators are magneto-optical materials that exhibit the Faraday magneto-optical effect. When an external magnetic field is applied, they can rotate the plane of vibration of incident polarized light. Furthermore, they exhibit low insertion loss in the optical communication band, making them widely used in optical communication isolators, optical rotators, and other optical devices. The main magneto-optical performance indicators of Faraday rotators include the Faraday rotation angle, temperature coefficient, wavelength coefficient, and insertion loss (IL = -10 * lg). T (T represents transmittance), saturation magnetic field, etc. Faraday rotators are sheet-shaped, with commonly used products measuring 11×11mm. When used in isolators, they require a 45° rotation of the polarized light to ensure high isolation. However, since the rotation angle of the polarization plane is wavelength-dependent, the application wavelength and thickness (transmission length) must correspond to ensure a 45° rotation angle for different communication wavelengths. Therefore, during product processing, the product must be ground and polished to the specified thickness according to the actual target wavelength. Consequently, within the optical communication application wavelength range, the product thickness typically varies between 0.3mm and 0.5mm.

[0003] The tests for Faraday rotation angle, wavelength coefficient, and temperature coefficient all involve measuring the rotation angle of the Faraday rotator. The test platforms are similar, all using a Faraday rotation angle test platform. This platform typically includes a light source (the wavelength needs to be adjustable when measuring the wavelength change coefficient), a magnet, a sample stage, a polarizer, an analyzer, a temperature controller (required when measuring the temperature change coefficient), and a power meter. Alternatively, replacing the analyzer and power meter with a polarization measuring instrument can achieve the same testing purpose. To test the saturation magnetic field, the ordinary magnet in the rotation angle test platform can be replaced with an electromagnet with an adjustable magnetic field strength, and an external Hall detector can be attached. By continuously increasing the current to the electromagnet, the magnetic field strength is increased until the Faraday rotation angle reaches its maximum value. The Hall detector is then used to detect the magnetic field strength at the sample location between the electromagnets at this point to confirm the saturation magnetic field. Alternatively, a vibrating sample magnetometer can be used to directly test the saturation magnetization curve of the Faraday rotator.

[0004] For commercial applications, the insertion loss (IL) of a Faraday rotator is generally required to be no higher than 0.1 dB to ensure that the isolator meets the low-loss requirements for conventional applications. When the actual transmittance of the Faraday rotator is 97.8%, the corresponding insertion loss IL is 0.1 dB. During testing, if the transmittance T has a ±1% error, meaning the measured value of T will randomly appear between 98.8% and 96.8%, the corresponding insertion loss IL value will randomly be obtained between 0.05 dB and 0.14 dB. This result has an error of 40% to 50% relative to the actual insertion loss value IL = 0.1 dB, resulting in serious distortion. Therefore, to obtain accurate insertion loss test results, the requirements for the testing platform are relatively high. Utility Model Content

[0005] In response to the deficiencies or improvement needs of existing technologies, this application provides a testing fixture and testing platform for the magneto-optical properties of Faraday rotatable sheets, aiming to solve the problem of large insertion loss testing errors in existing testing platforms.

[0006] According to one aspect of this application, a testing fixture for the magneto-optical properties of a Faraday rotator is provided, specifically including a base, a light-inlet plate, a light-outlet plate, a sample holder, and two magnets. The light-inlet plate and the light-outlet plate are disposed on the base with a gap between them. Each of the light-inlet plate and the light-outlet plate has a semi-enclosed magnet groove, with the groove opening facing away from the gap. The bottom of the magnet groove serves as a limiting plate disposed near the gap, and a first light-transmitting hole is formed at the center of the limiting plate. The sample holder is disposed in the gap between the light-inlet plate and the light-outlet plate for fixing the Faraday rotator plate, and a second light-transmitting hole is formed at the center of the sample holder. The two magnets are respectively inserted into the magnet grooves and limited by the limiting plates. A third light-transmitting hole is formed at the center of each magnet, and the third light-transmitting hole, the first light-transmitting hole, and the second light-transmitting hole are coaxially arranged.

[0007] Compared with the prior art, the technical solution conceived in this application integrates the magnet and the Faraday rotator plate onto the test fixture, which can magnetize the Faraday rotator plate to reduce scattered light and effectively reduce the length of the fixture parallel to the light transmission direction, ensuring that the light receiving probe can receive most of the emitted light, thereby solving the problem of large insertion loss test error.

[0008] As a further preferred embodiment, the light-inlet plate and the light-outlet plate are detachably connected to the base.

[0009] As a further preferred embodiment, the upper surface of the base is provided with a stepped structure, the light-inlet plate is provided on the higher stepped surface, and the light-outlet plate is provided on the lower stepped surface and abuts against the side wall of the step; or, the light-outlet plate is provided on the higher stepped surface, and the light-inlet plate is provided on the lower stepped surface and abuts against the side wall of the step.

[0010] As a further preferred embodiment, the thickness of the limiting plate is 0.5mm to 2.0mm.

[0011] As a further preferred embodiment, the apertures of the first and third light-transmitting holes are 1 mm to 10 mm, and the aperture of the second light-transmitting hole is not less than the apertures of the first and third light-transmitting holes.

[0012] As a further preferred embodiment, the gap width between the light-inlet plate and the light-outlet plate is 0.1 mm to 0.5 mm larger than the thickness of the sample holder.

[0013] As a further preferred embodiment, the sample holder has a semi-enclosed sample groove along a direction perpendicular to the base for placing the Faraday rotator plate, and the opening of the sample groove faces away from the base.

[0014] As a further preferred embodiment, the wall thickness of the sample groove is 0.5 mm to 2.0 mm along the direction parallel to the light propagation direction.

[0015] According to another aspect of this application, a test platform for the magneto-optical properties of a Faraday rotator plate, including the aforementioned test fixture, is provided.

[0016] As a further preferred embodiment, the test platform includes a test light source, a polarizer, a test fixture, and an optical power meter arranged sequentially along the light propagation direction, and the light outlet of the test light source, the optical path center of the polarizer, and the optical path center of the light receiving probe in the optical power meter are aligned with the central axis of the third light-passing hole in the test fixture.

[0017] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages:

[0018] 1. This application integrates a magnet and a Faraday rotator onto a test fixture, which can magnetize the Faraday rotator to reduce scattered light. At the same time, the integration and miniaturization of this test fixture can effectively reduce the length of the fixture parallel to the light transmission direction, making the light transmission direction, especially the output light end, as small as possible. This reduces the distance between the Faraday rotator and the light receiving probe, allowing the light receiving probe to receive most of the scattered light. In turn, by reducing scattered light and increasing the scattered light reception rate, the test error caused by scattering is reduced, effectively solving the problem of large insertion loss test error in existing test platforms.

[0019] 2. Meanwhile, by setting the upper surface of the base as a stepped structure, this application can utilize the sidewalls of the steps to achieve the contact between the light-inlet plate or the light-outlet plate, effectively simplifying the assembly of the test fixture;

[0020] 3. In addition, by optimizing the thickness of the limiting plate, this application can ensure the rigidity of the limiting plate while avoiding a weakening of the magnetic field strength. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view of the testing fixture for the magneto-optical properties of the Faraday rotatable sheet provided in the embodiments of this application;

[0022] Figure 2 This is a cross-sectional view of the testing fixture for the magneto-optical properties of the Faraday rotator provided in this embodiment of the application, without a magnet.

[0023] Figure 3 This is an overall schematic diagram of the testing fixture for the magneto-optical properties of the Faraday rotatable sheet provided in the embodiments of this application;

[0024] Figure 4 This is a schematic diagram of the testing platform for the magneto-optical performance of the Faraday rotatable sheet provided in the embodiments of this application.

[0025] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0026] 1-Base, 2-Light inlet plate, 3-Light outlet plate, 4-Sample clamp, 5-Faraday rotator, 6-Magnet groove, 7-Sample slot, 8-First light-passing hole, 9-Second light-passing hole, 10-Limiting plate, 11-Magnet, 12-Third light-passing hole, 13-Test light source, 14-Polarizer, 15-Test fixture, 16-Light receiving probe, 17-Optical power meter. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0028] like Figures 1-3As shown, this application provides a testing fixture for the magneto-optical properties of a Faraday rotatable plate, specifically including a base 1, a light-entry plate 2, a light-exit plate 3, a sample holder 4, and two magnets 11. The light-entry plate 2 and the light-exit plate 3 are mounted on the base 1 with a gap for placing the sample holder 4. Both the light-entry plate 2 and the light-exit plate 3 have semi-enclosed magnet grooves 6 along a direction parallel to the base 1. The opening of the magnet groove 6 faces away from the gap for inserting the magnet 11. Simultaneously, the bottom of the magnet groove 6 serves as a limiting plate 10 positioned near the gap for aligning the inserted magnet. The magnet 11 is positioned by limiting the position of the inserted magnet. The center of the limiting plate 10 has a first light-transmitting hole 8, and the groove wall of the magnet groove 6 forms a space for accommodating the magnet 11. The sample clip 4 is placed in the gap between the light-inlet plate 2 and the light-outlet plate 3 to fix the Faraday rotator plate 5. The center of the sample clip 4 has a second light-transmitting hole 9. The two magnets 11 are respectively inserted into the magnet groove 6. The center of the magnet 11 has a third light-transmitting hole 12, and the third light-transmitting hole 12, the first light-transmitting hole 8, and the second light-transmitting hole 9 are coaxially arranged to ensure that the light can propagate along the central axis.

[0029] In the magneto-optical performance testing of the Faraday rotatable plate, the distance between the Faraday rotatable plate 5 and the receiving probe 16 has a significant impact on the transmittance. During testing, light passing through the Faraday rotatable plate 5 is scattered. When the distance between the Faraday rotatable plate 5 and the receiving probe 16 is too great, the emitted light cannot be completely received by the receiving probe 16. Therefore, the greater the distance between the Faraday rotatable plate 5 and the receiving probe 16, the lower the light collection rate, resulting in a lower test transmittance. Furthermore, when the distance between the Faraday rotatable plate 5 and the receiving probe 16 is the same, applying an external magnetic field will also effectively increase the transmittance, and this transmittance-increasing effect weakens as the distance decreases.

[0030] Therefore, this application integrates the magnet 11 and the Faraday rotator 5 onto a test fixture, which can magnetize the Faraday rotator to reduce scattered light. Simultaneously, the integration and miniaturization of this test fixture effectively reduces the fixture length parallel to the light transmission direction, minimizing the light transmission direction, especially the output light end. This reduces the distance between the Faraday rotator 5 and the receiving probe 16, allowing the receiving probe to receive most of the scattered light. Furthermore, by reducing scattered light and increasing the scattered light reception rate, the test error caused by scattering is reduced, effectively solving the problem of large insertion loss test errors in existing test platforms. This makes the offline insertion loss test results more consistent with actual online applications. Moreover, the test fixture provided in this application can not only meet the requirements of insertion loss testing but can also be placed in a rotation angle test platform to test the Faraday rotation angle, temperature coefficient, wavelength coefficient, and other performance characteristics of the Faraday rotator 5.

[0031] Furthermore, the required magnetic field size or light spot may differ depending on the test conditions or when testing different Faraday rotators 5. Therefore, it is necessary to replace the light-inlet plate 2 and the light-outlet plate 3, which can accommodate magnets of different sizes and allow light of different spot sizes to pass through. To facilitate replacement, the light-inlet plate 2 and the light-outlet plate 3 are detachably connected to the base 1, rather than being designed as a single unit. Therefore, when it is necessary to replace certain parts of the test fixture, it is not necessary to replace the base 1 as well, effectively improving the applicability of the test fixture and reducing testing costs.

[0032] Furthermore, the bottom surface of the base 1 is flat, facilitating placement on a desktop or optical platform. The upper surface of the base 1 has a stepped structure. The light-inlet plate 2 is positioned on the higher stepped surface, and the light-outlet plate 3 is positioned on the lower stepped surface and abuts against the side wall of the step; alternatively, the light-outlet plate 3 is positioned on the higher stepped surface, and the light-inlet plate 2 is positioned on the lower stepped surface and abuts against the side wall of the step. The positions of the light-inlet plate 2 and the light-outlet plate 3 can be interchanged, but both must ensure that the central axis of the first light-transmitting hole 8 of the light-inlet plate 2 coincides with the central axis of the first light-transmitting hole 8 of the light-outlet plate 3. When assembling the test fixture, first push the light-inlet plate 2 or the light-outlet plate 3 positioned on the lower stepped surface close to the side wall of the step and fix it, thereby achieving the positioning function by abutting against the side wall of the step. Then push the light-outlet plate 3 or the light-inlet plate 2 positioned on the higher stepped surface and fix it.

[0033] The height and width of base 1 are unlimited. The actual test optical path height and optical platform size should be reasonably set, but the length parallel to the light transmission direction should be as short as possible while still allowing the placement of light inlet plate 2 and light outlet plate 3. The tops of light inlet plate 2 and light outlet plate 3 should be at the same height, that is, the height difference between the two plates should be one step.

[0034] Furthermore, if the limiting plate 10 is too thin, its rigidity will be weakened, causing the light-inlet plate 2 and the light-outlet plate 3 to undergo slight deformation due to the attraction between the two magnets 11. If the limiting plate 10 is too thick, the distance between the two magnets 11 will be too large, resulting in a weakening of the magnetic field strength at the Faraday rotator plate 5 and an increase in the distance between the Faraday rotator plate 5 and the light-receiving probe 16. Therefore, the thickness of the limiting plate 10 is preferably 0.5mm to 2.0mm.

[0035] Furthermore, the apertures of the first light-transmitting aperture 8 and the third light-transmitting aperture 12 are controlled within a certain range based on the size of the light spot of the test light source 13 and the size of the Faraday rotator plate 5. The diameter of the light spot of the test light source 13 is generally between several hundred micrometers and several millimeters, and the length × width × thickness of the Faraday rotator plate 5 is generally 11 × 11 × (0.3~0.5) mm. Therefore, the apertures of the first light-transmitting aperture 8 and the third light-transmitting aperture 12 are 1 mm to 10 mm, and the aperture of the second light-transmitting aperture 9 is not less than the apertures of the first light-transmitting aperture 8 and the third light-transmitting aperture 12.

[0036] Furthermore, the gap width between the light-inlet plate 2 and the light-outlet plate 3 needs to be consistent with the thickness of the sample clip 4 to fix the sample clip 4. However, in order to facilitate the installation of the sample clip 4, the gap width between the light-inlet plate 2 and the light-outlet plate 3 is 0.1mm to 0.5mm larger than the thickness of the sample clip 4.

[0037] Furthermore, the sample holder 4 has a sheet-like structure and a semi-enclosed sample groove 7 is formed along a direction perpendicular to the base 1 for placing the Faraday rotator plate 5. A second light-transmitting hole 9 on the sample holder 4 is formed on both sides of the sample groove 7 along a direction parallel to the light propagation direction. The opening of the sample groove 7 faces away from the base 1, facilitating the insertion of the Faraday rotator plate 5. The bottom of the sample groove 7 provides limiting support for the inserted Faraday rotator plate 5, while the groove wall of the sample groove 7 forms a space to accommodate the Faraday rotator plate 5. Therefore, the length, width, and thickness of the sample groove 7 are all set according to the standard Faraday rotator plate dimensions, with a positive margin. In a preferred embodiment of this application, the thickness margin of the sample groove 7 is 0.1 mm, set to 0.4 mm to 0.6 mm, and the length and width margins of the sample groove 7 are 0.5 mm, set to 11.5 mm × 11.5 mm. To maintain the rigidity of the sample holder 4 and prevent easy deformation, the wall thickness of the two side walls of the sample groove 7, parallel to the direction of light propagation, cannot be too thin, nor too thick. Otherwise, the distance between the two magnets placed in the light-inlet plate 2 and the light-outlet plate 3 would be too large, resulting in an insufficient magnetic field at the Faraday rotator plate. Therefore, the wall thickness of the two side walls of the sample groove 7 is 0.5 mm to 2.0 mm. In a preferred embodiment of this application, the sample thickness is 0.3 mm, the wall thickness of the two side walls of the sample groove 7 on the sample holder 4 is 1 mm, the total thickness of the sample holder 4 is 2.4 mm, and the gap between the light-inlet plate 2 and the light-outlet plate 3 has a positive margin of 0.2 mm relative to the sample holder 4. Correspondingly, the gap between the light-inlet plate 2 and the light-outlet plate 3 is 2.6 mm.

[0038] According to another aspect of this application, such as Figure 4 As shown, a test platform including the aforementioned test fixture is provided. The platform comprises a test light source 13, a polarizer 14, a test fixture 15, and an optical power meter 17 arranged sequentially along the light propagation direction. The light outlet of the test light source 13, the optical path center of the polarizer 14, and the optical path center of the light-receiving probe 16 in the optical power meter 17 are aligned with the central axis of the third light-passing aperture 12 in the test fixture 15. During operation, the light beam emitted by the test light source 13 is polarized by the polarizer 14 and enters the test fixture 15. After passing through the Faraday rotator 5, it exits and is collected by the light-receiving probe 16 and sent to the optical power meter 17. This test platform can test the insertion loss, Faraday rotation angle, temperature coefficient, wavelength coefficient, and other performance characteristics of the Faraday rotator 5.

[0039] The technical solutions provided in this application will be further described below with reference to specific embodiments.

[0040] Example 1

[0041] The operating steps for testing the insertion loss of a 11×11×0.3mm Faraday rotator 5 using the test fixture provided in this application at a wavelength of 1310nm are as follows:

[0042] (1) Set the light-emitting plate 3 with a diameter of 5mm for the first light-transmitting hole 8 on the low step surface of the base 1 and fix it against the side wall of the step. Move the light-inlet plate 2 with a diameter of 5mm for the first light-transmitting plate 8 closer to the light-emitting plate 3 and fix it when the gap between the two plates is 2.6mm.

[0043] (2) Insert magnets 11 with a diameter of 5mm and an outer diameter and length that match the size of the magnet grooves 6 into the magnet grooves 6 on the light inlet plate 2 and the light outlet plate 3 respectively, so that the magnets 11 are close to the gap side and tightly attached to the limiting plate 10 with a thickness of 1mm, and keep the two magnets attracted to each other.

[0044] (3) The gap magnetic field strength was tested using a Hall detector and confirmed to be greater than the saturation magnetization of the Faraday rotating plate 5 to be tested;

[0045] (4) Take a sample holder 4 with a wall thickness of 1 mm on both sides of the sample slot 7 and a total thickness of 2.4 mm. It has a sample slot 7 with a thickness of 0.4 mm and a second light-transmitting hole 9 with a diameter of 8 mm. It is horizontally inserted into the gap between the light-inlet plate 2 and the light-outlet plate 3.

[0046] (5) The base 1, the light inlet plate 2, the light outlet plate 3, the sample holder 4 and the magnet 11 constitute the test fixture to confirm that the central axes of the first light-transmitting hole 8, the second light-transmitting hole 9 and the third light-transmitting hole 12 coincide.

[0047] (6) Adjust the light output port of the test light source 13 with a wavelength of 1310nm, the center of the polarizer 14, the center of the test fixture 15 and the center of the light receiving probe 16 to be coaxial, and the light receiving probe 16 should be as close as possible to the light output plate 3.

[0048] (7) Start the test light source 13 through the light source control software. After it stabilizes, read the power reading of the optical power meter 17 and record it as I0.

[0049] (8) Use tweezers to pick up the 11mm×11mm×0.3mm Faraday rotator 5 and insert it into the sample slot 7. After stabilization, read the value of the optical power meter 17 and record it as I. 1；

[0050] (9) Calculate the transmittance T = I1 / I0, and the insertion loss IL = -10*lg T .

[0051] It should be understood that expressions such as "comprising" and "may include" as used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "comprising" and / or "having" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but should not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0052] It should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0053] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0054] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0055] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A test tool for Faraday rotator sheet magneto-optic performance, characterized in that, The application relates to a Faraday rotator magneto-optical performance testing device, which comprises a base (1), a light inlet plate (2), a light outlet plate (3), a sample holder (4) and two magnets (11), the light inlet plate (2) and the light outlet plate (3) are arranged on the base (1) and have a gap, a semi-closed magnet groove (6) is formed in the light inlet plate (2) and the light outlet plate (3), the groove opening of the magnet groove (6) faces away from the gap, the groove bottom of the magnet groove (6) is arranged as a limiting plate (10) on the side close to the gap, and a first light transmission hole (8) is formed in the center of the limiting plate (10); the sample holder (4) is arranged in the gap between the light inlet plate (2) and the light outlet plate (3) and is used for fixing a Faraday rotator (5), a second light transmission hole (9) is formed in the center of the sample holder (4); the two magnets (11) are respectively inserted into the magnet grooves (6) and are limited by the limiting plates (10), a third light transmission hole (12) is formed in the center of the magnet (11), and the third light transmission hole (12), the first light transmission hole (8) and the second light transmission hole (9) are coaxially arranged.

2. The test fixture of claim 1, wherein, The light inlet plate (2) and the light outlet plate (3) are detachably connected with the base (1).

3. The test fixture of claim 2, wherein, The upper surface of the base (1) is provided with a stepped structure, the light inlet plate (2) is arranged on the high step surface, the light outlet plate (3) is arranged on the low step surface and abuts against the step side wall, or the light outlet plate (3) is arranged on the high step surface, and the light inlet plate (2) is arranged on the low step surface and abuts against the step side wall.

4. The test fixture of claim 1, wherein, The thickness of the limiting plate (10) is 0.5mm-2.0mm 。 5. The test fixture of claim 1, wherein, The aperture of the first light transmission hole (8) and the third light transmission hole (12) is 1mm-10mm, and the aperture of the second light transmission hole (9) is not less than the aperture of the first light transmission hole (8) and the third light transmission hole (12).

6. The test fixture of claim 1, wherein, The gap width of the light inlet plate (2) and the light outlet plate (3) is 0.1mm-0.5mm larger than the thickness of the sample holder (4).

7. The test fixture of claim 1, wherein, The sample holder (4) is provided with a semi-closed sample groove (7) in the direction perpendicular to the base (1) and is used for placing the Faraday rotator (5), and the groove opening of the sample groove (7) faces away from the base (1).

8. The test fixture of claim 7, wherein, In the direction parallel to the light propagation direction, the wall thickness of the groove walls on both sides of the sample groove (7) is 0.5mm-2.0mm.

9. A Faraday rotator magneto-optical performance testing platform comprising the testing device according to any one of claims 1-8.

10. The test platform of claim 9, wherein, The testing device comprises a testing light source (13), a polarizer (14), the testing device (15) and a light power meter (17) arranged in sequence along the light propagation direction, and the light outlet of the testing light source (13), the light path center of the polarizer (14) and the light path center of the light receiving probe (16) in the light power meter (17) are aligned with the central axis of the third light transmission hole (12) in the testing device (15).

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