Magneto-optical depolarizer

Abstract

The utility model discloses a magneto-optical depolarizer, which comprises a laser source and a magneto-optical crystal arranged along the light propagation direction, the magneto-optical crystal is arranged above a magnetic guide rail, the magnetic guide rail generates a magnetic field parallel to the light propagation direction, and the magnetic field intensity is sequentially reduced along the direction vertical to the light propagation direction. And when passing through the magneto-optical crystal, the rotation angles of different areas of each micro-section on the optical surface are different so as to realize depolarization. According to the utility model, through more than one non-uniform magnetic field which linearly changes in the one-dimensional direction, the rotation angles of different areas of each micro-section on the optical surface are different so as to realize depolarization.

Description

Technical Field

[0001] This utility model relates to the fields of optics and lasers, and in particular to a magneto-optical depolarizer. Background Technology

[0002] The most common method for implementing depolarizers currently is to use a birefringent crystal structure with double wedge angles, which is suitable for depolarization of multiple wavelengths. For monochromatic linearly polarized light, some use a quarter-wave plate with a slow axis angle of 45 degrees, or a combination of quarter-wave and half-wave plates; or a combination of left-hand and right-hand rotating crystal prisms. Regarding depolarizers, the US patents include US4572608; US4968112; US5028134; US5408357; US5881158; US6522796; US66618521; US6735350; US6760495; US6830339; US6847744; US7072369; US7075644; US7254288; US8331024; US8797533; US9383490; US9599834; US10007041; US10809460; US10935399; and US2009 / 0296066, all of which are related to depolarizers. Over the past few decades, there have been no new conceptual breakthroughs in depolarizer design.

[0003] With the development of optical fiber communication technology, Garnet, a Faraday rotator made of LPE garnet Faraday magneto-optical rotator crystal in the optical communication band, can not only be mass-produced, but also has a thin product thickness, is inexpensive, and has a very low saturation magnetic field strength. It has been widely used in non-reciprocal passive optical components of optical fiber communication technology, such as isolators, circulators, switches and interleavers. Summary of the Invention

[0004] The purpose of this invention is to provide a magneto-optical depolarizer.

[0005] The technical solution adopted in this utility model is:

[0006] A magneto-optical depolarizer includes a laser source and a magneto-optical crystal arranged along the light propagation direction. The magneto-optical crystal is positioned above a magnetic rail, which generates a magnetic field parallel to the light propagation direction. The magnetic field strength decreases sequentially along the direction perpendicular to the light propagation direction, so that the rotation angle of different regions of each micro-section on the optical surface is different when passing through the magneto-optical crystal, thereby achieving depolarization.

[0007] Furthermore, the magnetic rail is composed of NdFeB and an iron plate, and a coil is set on the magnetic rail. When the coil is energized, the magnetic rail generates a magnetic field, and the magneto-optical depolarizer achieves depolarization.

[0008] Furthermore, the surface concentration of the magnetic rail at its center reaches 1.2T, and the concentration at a distance of 20mm from the center of the magnetic rail is 0.4T.

[0009] Furthermore, the magneto-optical crystal is a TGG crystal or a magneto-optical Faraday rotation Garnet crystal.

[0010] Furthermore, the laser source is a monochromatic laser or a broadband laser.

[0011] Furthermore, the magnetic rail has two or more different magnetic fields along the direction of light propagation, and the magnetic field strength of the different magnetic fields is different at the same level.

[0012] Furthermore, there are two magneto-optical crystals, spaced apart, with magnetic rails corresponding to different magnetic fields for each crystal. Moreover, the magnetic field strength of the different crystals decreases in different directions; that is, they belong to the same plane perpendicular to the light propagation direction, but their magnetic field strength decreases in different directions along the same plane.

[0013] Furthermore, the laser emission direction of the magneto-optical crystal is provided with a reflector that forms an acute angle with the plane perpendicular to the light propagation direction; the reflector reflects the emitted laser light from the magneto-optical crystal back to the magneto-optical crystal at a specified angle.

[0014] Furthermore, two or more reflectors are alternately arranged at tilt angles on the incident and exit surfaces of the magneto-optical crystal; the reflectors reflect the laser back and forth so that it passes through the magneto-optical crystal multiple times.

[0015] This invention employs the above technical solutions, utilizing magneto-optical crystals, magneto-optical glass, and magneto-optical Faraday-rotation Garnet crystals. Its optical transmission surface is placed in a non-uniform magnetic field, such as a magnetic field with approximately linear changes in one dimension. This causes different positions on the optical wavefront to rotate at different angles in the one-dimensional direction, thereby achieving depolarization across the overall beam cross-section. Alternatively, this invention can sequentially construct perpendicular non-uniform magnetic fields using two linearly changing one-dimensional directions, resulting in different rotation angles in different regions of each micro-section on the optical surface to achieve depolarization. Furthermore, this invention can utilize multiple back-and-forth reflections to increase the rotation angle at each point through magneto-optical materials. Attached Figure Description

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments;

[0017] Figure 1 This is a schematic diagram illustrating the structural principle of a magneto-optical depolarizer according to this utility model;

[0018] Figure 2 This is a schematic diagram of the light spot phase distribution at position B of this utility model;

[0019] Figure 3This is one of the schematic diagrams of an embodiment of a magneto-optical depolarizer according to this utility model;

[0020] Figure 4 This is the second schematic diagram of the implementation structure of a magneto-optical depolarizer according to this utility model. Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0022] like Figure 1 As shown in Figure 2, this utility model discloses a magneto-optical depolarizer, which includes a laser source 1 and a magneto-optical crystal 2 arranged along the light propagation direction. The magneto-optical crystal 2 is arranged above a magnetic rail 3. The magnetic rail 3 generates a magnetic field parallel to the light propagation direction, and the magnetic field strength decreases sequentially along the perpendicular light propagation direction, so that the rotation angle of different regions of each micro-section on the optical surface is different when passing through the magneto-optical crystal 2, so as to achieve depolarization.

[0023] Furthermore, the magnetic rail 3 is composed of NdFeB and an iron plate, and a coil is set on the magnetic rail 3. When the coil is energized, the magnetic rail 3 generates a magnetic field, and the magneto-optical depolarizer realizes depolarization.

[0024] Furthermore, the surface concentration of magnetic flux at the center of magnetic rail 3 reaches 1.2T, and the concentration at a distance of 20mm from the surface of magnetic rail 3 is 0.4T.

[0025] Furthermore, magneto-optical crystal 2 is a TGG crystal or a magneto-optical Faraday rotation Garnet crystal.

[0026] Furthermore, laser source 1 is a monochromatic laser or a broadband laser.

[0027] Furthermore, the magnetic rail 3 has two or more different magnetic fields along the direction of light propagation, and the magnetic field strength of the different magnetic fields is different at the same level.

[0028] Furthermore, such as Figure 3 As shown, there are two magneto-optical crystals 2, which are arranged at intervals. The magnetic rails 3 correspond to different magnetic fields for each magneto-optical crystal 2. Furthermore, the magnetic field strength of the different magneto-optical crystals 2 decreases in different directions, that is, they belong to the same plane perpendicular to the direction of light propagation, but the magnetic field strength decreases in different directions along the same plane.

[0029] Furthermore, such as Figure 4 As shown, the laser emission direction of the magneto-optical crystal 2 is provided with a reflector that forms an acute angle with the plane perpendicular to the light propagation direction; the reflector reflects the emitted laser from the magneto-optical crystal 2 back to the magneto-optical crystal 2 at a specified angle.

[0030] Furthermore, two or more reflective elements are alternately arranged at tilt angles on the incident and exit surfaces of the magneto-optical crystal 2; the reflective elements reflect the laser back and forth so that it passes through the magneto-optical crystal 2 multiple times.

[0031] Due to the need for high-power laser isolators, magneto-optical crystals such as TGG can be mass-produced cheaply; at the same time, high magnetic field strength rare earth permanent magnet materials are also widely used, so this invention can be made into a depolarizer with a wide wavelength range at very low cost; and the non-uniform magnetic field of this invention can also be generated by energizing a coil, so the depolarizer can have a dynamic function: it can depolarize or not depolarize.

[0032] This invention employs the above technical solution, using a magneto-optical crystal 2, magneto-optical glass, and a magneto-optical Faraday-rotation Garnet crystal. Its optical transmission surface is placed in a non-uniform magnetic field, such as a magnetic field with approximately linear changes in one dimension. This causes different positions on the optical wavefront to rotate at different angles in one dimension, thus achieving depolarization across the overall beam cross-section. Alternatively, this invention can sequentially construct perpendicular non-uniform magnetic fields using two linearly changing one-dimensional directions, resulting in different rotation angles in different regions of each micro-section on the optical surface to achieve depolarization. Furthermore, this invention can utilize multiple back-and-forth reflections to increase the rotation angle at each point through the magneto-optical material.

[0033] Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. Without conflict, the embodiments and features in the embodiments of this application can be combined with each other. The components of the embodiments of this application described and illustrated herein can generally be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A magneto-optical depolarizer, characterized in that: It includes a laser source and a magneto-optical crystal arranged along the direction of light propagation. The magneto-optical crystal is positioned above a magnetic rail, which generates a magnetic field parallel to the direction of light propagation. The magnetic field strength decreases sequentially along the direction perpendicular to the direction of light propagation, so that the rotation angle of different regions of each micro-section on the optical surface is different when passing through the magneto-optical crystal, thereby achieving depolarization.

2. The magneto-optical depolarizer according to claim 1, characterized in that: The magnetic rail is composed of NdFeB and an iron plate. A coil is set on the magnetic rail. When the coil is energized, the magnetic rail generates a magnetic field, and the magneto-optical depolarizer achieves depolarization.

3. The magneto-optical depolarizer according to claim 1, characterized in that: The surface concentration of the magnetic rail at its center reaches 1.2T, while the concentration at a distance of 20mm from the center of the magnetic rail is 0.4T.

4. The magneto-optical depolarizer according to claim 1, characterized in that: The magneto-optical crystal is either a TGG crystal or a magneto-optical Faraday rotation Garnet crystal.

5. A magneto-optical depolarizer according to claim 1, characterized in that: The laser source is a monochromatic laser or a broadband laser.

6. A magneto-optical depolarizer according to claim 1, characterized in that: The magnetic rail has two or more different magnetic fields along the direction of light propagation, and the magnetic field strength of the different magnetic fields is different at the same level.

7. A magneto-optical depolarizer according to claim 1, characterized in that: There are two magneto-optical crystals, which are set at intervals. The magnetic rails correspond to different magnetic fields for each magneto-optical crystal.

8. A magneto-optical depolarizer according to claim 1, characterized in that: The laser emission direction of the magneto-optical crystal is provided with a reflector that forms an acute angle with the plane perpendicular to the light propagation direction; the reflector reflects the emitted laser from the magneto-optical crystal back to the magneto-optical crystal at a specified angle.

9. A magneto-optical depolarizer according to claim 8, characterized in that: Two or more reflectors are alternately arranged at tilt angles on the incident and exit surfaces of the magneto-optical crystal; the reflectors reflect the laser back and forth so that it passes through the magneto-optical crystal multiple times.

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