Nondestructive switching magneto-optical switch

Abstract

The invention discloses a lossless switching magneto-optical switch, and belongs to the field of optics, a first polarization splitting prism decomposes parallel light input by an input end into two sub light beams p light and s light which are orthogonal in polarization direction, the p light and the s light are two main light paths, a first half-wave plate can clockwise rotate the polarization direction of the p light along the light path transmission direction by 135 degrees, and a second half-wave plate can clockwise rotate the polarization direction of the p light along the light path transmission direction by 135 degrees; the polarization direction of the s light anticlockwise rotates by 45 degrees along the light path transmission direction, the Faraday optical rotation crystal enables the light of the main light path to clockwise rotate by 45 degrees or anticlockwise rotate by 45 degrees by applying magnetic fields in different directions, and two weak light paths are generated at the same time; the second polarization splitting prism converges the p light and the s light of the two main light paths to the first output end or the second output end and converges the p light and the s light of the two weak light paths to the other second output end or the first output end, and when light channels are switched, the strong light and the weak light are coupled into different channels. The sum of energy at the first output end and the second output end and the sum of energy at the first output end and the second output end after switching are always in a stable state, so that network transmission is stable.

Description

Technical Field

[0001] The invention relates to the field of optical elements, and in particular to a lossless switching magneto-optical switch. Background Art

[0002] In the field of fiber-optic communication, optical switches, as an important component of passive devices, are widely used in fiber-optic communication networks to selectively switch optical signals. Magneto-optical switches are optical switches that use the Faraday magneto-optical effect. They mainly change the direction of the Faraday rotation angle in the magneto-optical crystal by changing the direction of the external magnetic field, thereby achieving the purpose of switching the optical path. Compared with traditional optical switches, magneto-optical switches have the advantages of fast switching speed, no moving parts, and high stability, and have received more and more attention and research.

[0003] When the magneto-optical switch is working, the connected light path is the main energy, and the closed light path is not actually in a light-free state, but the light energy is relatively weak. During the actual switching process of the existing magneto-optical switch, when the light energy is switched from one path to another, the sum of the light energy in each port cannot maintain a stable value. The energy loss caused by the switch switching affects the stability of the optical transmission system. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, one of the objectives of the present invention is to provide a magneto-optical switch for lossless switching in which the sum of the optical energy in each port maintains a stable value.

[0005] One of the purposes of the present invention is achieved by the following technical solution:

[0006] A lossless switching magneto-optical switch comprises an input end, a first output end, a second output end, and a first polarization beam splitter prism, a first half-wave plate, a Faraday rotator crystal and a second polarization beam splitter prism arranged in sequence, wherein the input end is located on the side of the first polarization beam splitter prism away from the first half-wave plate, the first output end and the second output end are located on the side of the second polarization beam splitter prism away from the Faraday rotator crystal, the first polarization beam splitter prism and the second polarization beam splitter prism each comprise two crystals, the two crystals are coated at the joint, and the first polarization beam splitter prism decomposes the parallel light input from the input end into two sub-beams with orthogonal polarization directions. The invention relates to a light beam p and an s light, wherein the p light and the s light are two main light paths, the first half-wave plate can rotate the polarization direction of the p light by 135° clockwise along the light path transmission direction, and the polarization direction of the s light can be rotated by 45° counterclockwise along the light path transmission direction, the Faraday rotator crystal can rotate the main light path light by 45° clockwise or 45° counterclockwise by applying magnetic fields in different directions, and at the same time, the polarization direction of a very weak light beam is not rotated to generate two weak light paths, and the second polarization beam splitter prism converges the p light and the s light of the two main light paths to the first output end or the second output end, and converges the p light and the s light of the two weak light paths to the other second output end or the first output end.

[0007] Furthermore, the two crystals of the first polarization beam splitter prism are respectively a parallelogram crystal and a triangular crystal, and the mating surfaces of the parallelogram crystal and the triangular crystal are coated with a film, and the film reflects S light.

[0008] Furthermore, the two crystals of the second polarization beam splitter prism are respectively two parallelogram crystals, and the mating surfaces of the two parallelogram crystals are coated with a film, and the film reflects the s light and transmits the p light.

[0009] Furthermore, the lossless switching magneto-optical switch also includes a second half-wave plate and a third half-wave plate, the second half-wave plate is located between the first polarization beam splitter prism and the first half-wave plate, the second half-wave plate is located on the p light channel emitted from the first polarization beam splitter prism, the third half-wave plate is located between the Faraday rotator crystal and the second polarization beam splitter prism, and the third half-wave plate is located on the s light channel emitted from the first polarization beam splitter prism.

[0010] Further, the position of the second half-wave plate corresponds to the triangular crystal of the first polarization beam splitter prism, and the position of the third half-wave plate corresponds to the parallelogram crystal of the first polarization beam splitter prism.

[0011] Furthermore, the lossless switching magneto-optical switch also includes a first single-fiber collimator, which is located at the input end and collimates the divergent light beam output by the optical fiber into a parallel light beam.

[0012] Furthermore, the lossless switching magneto-optical switch also includes a second single fiber collimator and a third single fiber collimator, and the second single fiber collimator and the third single fiber collimator are respectively located at the first output end and the second output end.

[0013] Furthermore, the parallel light beam emitted by the first single fiber collimator, the light beam received by the second single fiber collimator, and the light beam received by the third single fiber collimator are parallel to each other.

[0014] Compared with the prior art, the present invention provides a lossless switching magneto-optical switch, comprising a first polarization beam splitter prism, a first half-wave plate, a Faraday rotator crystal and a second polarization beam splitter prism arranged in sequence, wherein the input end is located on the side of the first polarization beam splitter prism away from the first half-wave plate, the first output end and the second output end are located on the side of the second polarization beam splitter prism away from the Faraday rotator crystal, the first polarization beam splitter prism and the second polarization beam splitter prism each comprise two crystals, the two crystals are coated at the joint, the first polarization beam splitter prism converts the polarization beam input at the input end into The traveling light is decomposed into two sub-beams, p light and s light, with orthogonal polarization directions. The p light and s light are two main light paths. The first half-wave plate can rotate the polarization direction of the p light by 135° clockwise along the transmission direction of the light path, and the polarization direction of the s light by 45° counterclockwise along the transmission direction of the light path. The Faraday rotator crystal rotates the main light path by 45° clockwise or 45° counterclockwise by applying magnetic fields in different directions. At the same time, the polarization direction of the very weak light beam does not rotate to produce two weak light paths. The second polarization beam splitter rotates the p light of the two main light paths. The P light and S light are converged to the first output end or the second output end, and the P light and S light of the two weak light paths are converged to another second output end or the first output end. The polarization direction of the light beam is changed by setting a polarization beam splitter prism, a first half-wave plate and a Faraday rotator crystal to ensure that all light beams can be accurately converged to the output end after passing through the second polarization beam splitter prism. When the optical channel is switched, it is essentially the intensity of the strong light and the weak light on the path is exchanged, and the strong light and the weak light are coupled into different channels. When the switch is switched, it actually takes a certain response time to complete the switching. During the time when the switching starts but the switching is not completed, when the energy is converted between the strong light and the weak light, the energy of the weak light will increase. However, since the magneto-optical switch in the prior art does not couple the weak light channel, instability occurs in the system, and it will not stabilize until all the switches are completed. In the present application, the sum of the energies at the first output end and the second output end and the sum of the energies at the first output end and the second output end after the switching is completed are always in a stable state, which brings stability to the network transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A three-dimensional diagram of a magneto-optical switch for lossless switching according to a first embodiment of the present invention;

[0016] Figure 2 This is a light path diagram from the input end to the first output end during operation in the first embodiment of the present invention;

[0017] Figure 3 This is a light path diagram from the input end to the second output end in operation in the first embodiment of the present invention;

[0018] Figure 4 A three-dimensional diagram of a magneto-optical switch for lossless switching according to a second embodiment of the present invention;

[0019] Figure 5 This is a light path diagram from the input end to the first output end in operation in the second embodiment of the present invention;

[0020] Figure 6 This is a light path diagram from the input end to the second output end in operation in the second embodiment of the present invention.

[0021] In the figure: 101, a first single-fiber collimator; 102, a first polarization beam splitter prism; 103, a first half-wave plate; 104, a Faraday rotator crystal; 105, a second polarization beam splitter prism; 106, a second single-fiber collimator; 107, a third single-fiber collimator; 108, a second half-wave plate; 109, a third half-wave plate. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may be another intermediate component through which it is fixed. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be another intermediate component at the same time. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be another intermediate component at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0025] First embodiment

[0026] See also Figures 1 to 3 , which is the first embodiment of the present application, a lossless switching magneto-optical switch includes a first single fiber collimator 101, a first polarization beam splitter prism 102, a first half-wave plate 103, a Faraday rotator crystal 104, a second polarization beam splitter prism 105, a second single fiber collimator 106, and a third single fiber collimator 107, which are arranged in sequence.

[0027] The first single fiber collimator 101 is used to collimate the incident light at the input end into a parallel light beam. The first single fiber collimator 101 is located at the input end P1.

[0028] The first polarization beam splitter prism 102 includes two crystals, and the two crystals are coated at the joint. Specifically, the two crystals of the first polarization beam splitter prism 102 are respectively a parallelogram crystal and a triangular crystal, and the parallelogram crystal and the triangular crystal are coated at the joint surface, and the film reflects the s light and transmits the p light. The first polarization beam splitter prism 102 decomposes the parallel light input at the input end into two sub-beams of p light and s light with orthogonal polarization directions. At this time, the p light and the s light are two main light paths. After being coated, the p light can be directly transmitted and transmitted along the optical path below. The s light is first reflected at the coating, and then undergoes total reflection at the interface between the parallelogram crystal and the external air, and is transmitted along the optical path above.

[0029] The first half-wave plate 103 rotates the polarization direction of the p-light by 135° clockwise along the optical transmission direction, and rotates the polarization direction of the s-light by 45° counterclockwise along the optical transmission direction.

[0030] The Faraday rotator crystal 104 controls the operation of different channels of the magneto-optical switch by changing the direction of the magnetic field by connecting different positive and negative poles of the voltage. The Faraday rotator crystal 104 rotates the polarization directions of the two sub-beams of the main optical path. Due to the relationship between the extinction ratio of the Faraday and the wave plate, not 100% of the sub-beams are concentrated in the ideal polarization state, and the polarization directions of some very weak beams are not rotated, forming two weak optical paths.

[0031] The second polarization beam splitter prism 105 is used for combining light, and includes two crystals, and the joint of the two crystals is coated. Specifically, the second polarization beam splitter prism 105 includes two parallelogram crystals, and the joint surface of the two parallelogram crystals is coated with a film, and the film reflects the s light.

[0032] The second single fiber collimator 106 is located at the first output end P2, and the third single fiber collimator 107 is located at the first output end P3.

[0033] Please continue reading Figure 2, when the magneto-optical switch is in the input end P1->first output end P2 optical path channel: observed in the light transmission direction, when P1 to P2 is connected, the working principle is as follows:

[0034] The divergent light beam outputted from the optical fiber (input end P1) is first collimated into a parallel light beam by the first single-fiber collimator 101; after the parallel light beam passes through the first polarization beam splitter prism 102, the parallel light beam is decomposed into two sub-beams p-light and s-light with orthogonal polarization directions. The p-light can be directly transmitted after being coated and transmitted along the optical path below. The s-light is first reflected at the coating, and then undergoes total reflection at the interface between the parallelogram crystal and the external air, and is transmitted along the optical path above; when passing through the first half-wave plate 103, the polarization direction of the p-light rotates 135° clockwise along the transmission direction of the optical path, and the polarization direction of the s-light rotates 45° counterclockwise along the transmission direction of the optical path. After passing through the Faraday rotator crystal 104, the polarization directions of the two sub-beams rotate 45° clockwise along the transmission direction of the optical path. At this time, the p-light emitted at the first polarization beam splitter prism 102 is still the p-light, and the s-light is still the s-light. This part of the optical path belongs to the main optical path. Due to the extinction ratio between Faraday and wave plate, not 100% of the sub-beams are concentrated in the ideal polarization state, and there are some very weak beams whose polarization directions are not rotated. This part of the beam is the p-light emitted from the first polarization splitter prism 102 that changes into s-light, and s-light changes into p-light. This part of the light path belongs to the weak light path.

[0035] After passing through the second polarization beam splitter prism 105, the connection between the two parallelogram crystals is subjected to a coating treatment, and the p-light can be directly transmitted after passing through the film, and the s-light will be reflected after passing through the film. In the main optical path, the p-light first passes through the lower parallelogram crystal, and a total reflection phenomenon occurs at the interface between the parallelogram crystal and the external air, and then transmits through the thin film connected by the two parallelogram crystals, and then passes through the upper parallelogram crystal, and a total reflection phenomenon occurs at the interface between the parallelogram crystal and the external air, and finally transmits to the second single-fiber collimator 106 (i.e., the first output end P2); the s-light first reflects at the thin film connected by the two parallelogram crystals, and then passes through the upper parallelogram crystal, and a total reflection phenomenon occurs at the interface between the parallelogram crystal and the external air, and finally transmits to the second single-fiber collimator 106 (i.e., the first output end P2). In the weak light path, the p light is directly transmitted through the thin film connected by the two parallelogram crystals, and is transmitted to the third single-fiber collimator 107 (i.e., the second output end P3); the s light first passes through the parallelogram crystal below, undergoes total reflection at the interface between the parallelogram crystal and the external air, and is then reflected at the thin film connected by the two parallelogram crystals, and is transmitted to the third single-fiber collimator 107 (i.e., the second output end P3).

[0036] Please continue reading Figure 3, when the magneto-optical switch is in the input end P1->second output end P3 optical path channel working (main optical path): observed in the direction of light transmission, when P1 to P3 are connected, the working principle is as follows:

[0037] The divergent light beam outputted from the optical fiber (input end P1) is first collimated into a parallel light beam by the first single-fiber collimator 101; after the parallel light beam passes through the first polarization beam splitter prism 102, the parallel light beam is decomposed into two sub-beams p light and s light with orthogonal polarization directions. The p light can be directly transmitted after being coated and transmitted along the optical path below. The s light is first reflected at the coating, and then undergoes total reflection at the interface between the parallelogram crystal and the external air, and is transmitted along the optical path above; when passing through the first half-wave plate 103, the polarization direction of the p light rotates 135° clockwise along the optical path transmission direction, and the polarization direction of the s light rotates 45° counterclockwise along the optical path transmission direction. After passing through the Faraday rotator crystal 104, the polarization directions of the two sub-beams rotate 45° counterclockwise along the optical path transmission direction. At this time, the light emitted at the first polarization beam splitter prism 102 changes to s light, and the s light changes to p light. This part of the optical path belongs to the main optical path. Due to the extinction ratio between Faraday and wave plate, not 100% of the sub-beams are concentrated in the ideal polarization state, and there are some very weak beams whose polarization directions are not rotated. This part of the beam is the p light emitted from the first polarization splitter prism 102, and the s light is still the s light. This part of the light path belongs to the weak light path.

[0038] After passing through the second polarization beam splitter prism 105, the connection between the two parallelogram crystals is subjected to a coating treatment, and the p-light can be directly transmitted after passing through the film, and the s-light will be reflected after passing through the film. In the main optical path, the p-light is directly transmitted through the film connected by the two parallelogram crystals, and is transmitted to the third single-fiber collimator 107 (i.e., the second output end P3); the s-light first passes through the parallelogram crystal below, and is totally reflected at the interface between the parallelogram crystal and the external air, and then is reflected at the film connected by the two parallelogram crystals, and is transmitted to the third single-fiber collimator 107 (i.e., the second output end P3). In the weak light path, the p light first passes through the parallelogram crystal below, and is totally reflected at the interface between the parallelogram crystal and the external air, then is transmitted through the thin film connected by the two parallelogram crystals, then passes through the parallelogram crystal above, and is totally reflected at the interface between the parallelogram crystal and the external air, and finally is transmitted to the second single-fiber collimator 106 (i.e., the first output end P2); the s light first is reflected at the thin film connected by the two parallelogram crystals, then passes through the parallelogram crystal above, and is totally reflected at the interface between the parallelogram crystal and the external air, and finally is transmitted to the second single-fiber collimator 106 (i.e., the first output end P2).

[0039] Second embodiment

[0040] Please continue reading Figures 4 to 6 , which is the second embodiment of the present application, a lossless switching magneto-optical switch includes a first single fiber collimator 101, a first polarization beam splitter prism 102, a second half-wave plate 108, a first half-wave plate 103, a Faraday rotator crystal 104, a third half-wave plate 109, a second polarization beam splitter prism 105, a second single fiber collimator 106 and a third single fiber collimator 107 which are arranged in sequence.

[0041] The first single fiber collimator 101 is used to collimate the incident light at the input end into a parallel light beam. The first single fiber collimator 101 is located at the input end P1.

[0042] The first polarization beam splitter prism 102 includes two crystals, and the two crystals are coated at the joint. Specifically, the two crystals of the first polarization beam splitter prism 102 are respectively a parallelogram crystal and a triangular crystal, and the parallelogram crystal and the triangular crystal are coated at the joint surface, and the film reflects the s light and transmits the p light. The first polarization beam splitter prism 102 decomposes the parallel light input at the input end into two sub-beams of p light and s light with orthogonal polarization directions. At this time, the p light and the s light are two main light paths. After being coated, the p light can be directly transmitted and transmitted along the optical path below. The s light is first reflected at the coating, and then undergoes total reflection at the interface between the parallelogram crystal and the external air, and is transmitted along the optical path above.

[0043] The position of the second half-wave plate 108 corresponds to the triangular crystal of the first polarization beam splitter prism 102 . The second half-wave plate 108 rotates the polarization direction of the p-light by 90° counterclockwise along the transmission direction of the optical path, and the p-light is converted into s-light.

[0044] The first half-wave plate 103 rotates the polarization direction of the s-light by 45° counterclockwise along the optical transmission direction.

[0045] The Faraday rotator crystal 104 controls the operation of different channels of the magneto-optical switch by changing the direction of the magnetic field by connecting different positive and negative poles of the voltage. The Faraday rotator crystal 104 rotates the polarization directions of the two sub-beams of the main optical path. Due to the relationship between the extinction ratio of the Faraday and the wave plate, not 100% of the sub-beams are concentrated in the ideal polarization state, and the polarization directions of some very weak beams are not rotated, forming two weak optical paths.

[0046] The position of the third half-wave plate 109 corresponds to the quadrilateral crystal of the first polarization splitter prism 102. The third half-wave plate 109 rotates the s-light of the main light path 90° counterclockwise along the propagation direction of the light path, and rotates the p-light of the weak light path 90° clockwise along the propagation direction of the light path. At this time, the s-light in the upper main light path is converted into p-light, and the p-light in the weak light path is converted into s-light.

[0047] The second polarization beam splitter prism 105 is used for combining light, and includes two crystals, and the joint of the two crystals is coated. Specifically, the second polarization beam splitter prism 105 includes two parallelogram crystals, and the joint surface of the two parallelogram crystals is coated with a film, and the film reflects the s light.

[0048] The second single fiber collimator 106 is located at the first output end P2, and the third single fiber collimator 107 is located at the first output end P3.

[0049] Please continue reading Figure 5 , when the magneto-optical switch is in the input end P1->first output end P2 optical path channel: observed in the light transmission direction, when P1 to P2 is connected, the working principle is as follows:

[0050] The divergent light beam outputted from the optical fiber (input end P1) is first collimated into a parallel light beam by the first single-fiber collimator 101; after the parallel light beam passes through the first polarization beam splitter prism 102, the parallel light beam is decomposed into two sub-beams p light and s light with orthogonal polarization directions. The p light can be directly transmitted after being coated and transmitted along the optical path below. The s light is first reflected at the coating, and then undergoes total reflection at the interface between the parallelogram crystal and the external air, and is transmitted along the optical path above; the second half-wave plate 108 is in the optical path below, and since the s light does not pass through the second half-wave plate 108, it continues to propagate in the air medium. After the p-light passes through the second half-wave plate 108, the polarization direction rotates 90° counterclockwise along the transmission direction of the optical path. At this time, the p-light is converted into s-light, and the sub-beams on the two optical paths are all s-light; after passing through the first half-wave plate 103, the polarization directions of the two sub-beams rotate 45° counterclockwise along the transmission direction of the optical path; after passing through the Faraday rotator crystal 104, the polarization directions of the two sub-beams rotate 45° counterclockwise along the transmission direction of the optical path. At this time, the two sub-beams are changed from s-light to p-light, and this part of the optical path belongs to the main optical path. Due to the relationship between the extinction ratio of Faraday and the wave plate, not 100% of the sub-beams are concentrated in the ideal polarization state, and there are some very weak beams whose polarization directions have not rotated. This part of the beam is still s-light, and this part of the optical path belongs to the weak optical path; in the optical path above the third half-wave plate 109, since the p-light at the bottom does not pass through the third half-wave plate 109, it continues to propagate along the air medium. The p light in the upper main light path rotates 90° clockwise along the light path propagation direction, and the s light in the weak light path rotates 90° counterclockwise along the light path propagation direction. At this time, the p light in the upper main light path is converted into s light, and the s light in the weak light path is converted into p light;

[0051] After passing through the second polarization beam splitter prism 105, the connection between the two parallelogram crystals is subjected to a coating treatment, and the p-light can be directly transmitted after passing through the film, and the s-light will be reflected after passing through the film. In the main optical path, the p-light first passes through the lower parallelogram crystal, and a total reflection phenomenon occurs at the interface between the parallelogram crystal and the external air, and then transmits through the thin film connected by the two parallelogram crystals, and then passes through the upper parallelogram crystal, and a total reflection phenomenon occurs at the interface between the parallelogram crystal and the external air, and finally transmits to the second single-fiber collimator 106 (i.e., the first output end P2); the s-light first reflects at the thin film connected by the two parallelogram crystals, and then passes through the upper parallelogram crystal, and a total reflection phenomenon occurs at the interface between the parallelogram crystal and the external air, and finally transmits to the second single-fiber collimator 106 (i.e., the first output end P2). In the weak light path, the p light is directly transmitted through the thin film connected by the two parallelogram crystals, and is transmitted to the third single-fiber collimator 107 (i.e., the second output end P3); the s light first passes through the parallelogram crystal below, undergoes total reflection at the interface between the parallelogram crystal and the external air, and is then reflected at the thin film connected by the two parallelogram crystals, and is transmitted to the third single-fiber collimator 107 (i.e., the second output end P3).

[0052] Please continue reading Figure 6 , when the magneto-optical switch is in the input end P1->second output end P3 optical path channel working (main optical path): observed in the direction of light transmission, when P1 to P3 are connected, the working principle is as follows:

[0053] The divergent light beam outputted from the optical fiber (input end P1) is first collimated into a parallel light beam by the first single-fiber collimator 101; after the parallel light beam passes through the first polarization beam splitter prism 102, the parallel light beam is decomposed into two sub-beams p light and s light with orthogonal polarization directions. The p light can be directly transmitted after being coated and transmitted along the optical path below. The s light is first reflected at the coating, and then undergoes total reflection at the interface between the parallelogram crystal and the external air, and is transmitted along the optical path above; the second half-wave plate 108 is in the optical path below, and since the s light does not pass through the second half-wave plate 108, it continues to propagate in the air medium. After the p-light passes through the second half-wave plate 108, the polarization direction rotates 90° counterclockwise along the transmission direction of the optical path. At this time, the p-light is converted into s-light, and the sub-beams on the two optical paths are all s-light; after passing through the first half-wave plate 103, the polarization directions of the two sub-beams rotate 45° counterclockwise along the transmission direction of the optical path; after passing through the Faraday rotator crystal 104, the polarization directions of the two sub-beams rotate 45° clockwise along the transmission direction of the optical path. At this time, the two sub-beams are still s-light, and this part of the optical path belongs to the main optical path. Due to the relationship between the extinction ratio of Faraday and the wave plate, not 100% of the sub-beams are concentrated in the ideal polarization state, and the polarization direction of some very weak beams does not rotate. This part of the beam is changed from s-light to p-light, and this part of the optical path belongs to the weak optical path;

[0054] The third half-wave plate 109 is in the upper optical path. Since the s-light at the lower side does not pass through the third half-wave plate 109, it continues to propagate along the air medium. The s-light at the upper main optical path rotates 90° counterclockwise along the optical path propagation direction, and the p-light at the weak optical path rotates 90° clockwise along the optical path propagation direction. At this time, the s-light at the upper main optical path is converted into p-light, and the p-light at the weak optical path is converted into s-light.

[0055] After passing through the second polarization beam splitter prism 105, the connection between the two parallelogram crystals is subjected to a coating treatment, and the p-light can be directly transmitted after passing through the film, and the s-light will be reflected after passing through the film. In the main optical path, the p-light is directly transmitted through the film connected by the two parallelogram crystals, and is transmitted to the third single-fiber collimator 107 (i.e., the second output end P3); the s-light first passes through the parallelogram crystal below, and is totally reflected at the interface between the parallelogram crystal and the external air, and then is reflected at the film connected by the two parallelogram crystals, and is transmitted to the third single-fiber collimator 107 (i.e., the second output end P3). In the weak light path, the p light first passes through the parallelogram crystal below, and is totally reflected at the interface between the parallelogram crystal and the external air, then is transmitted through the thin film connected by the two parallelogram crystals, then passes through the parallelogram crystal above, and is totally reflected at the interface between the parallelogram crystal and the external air, and finally is transmitted to the second single-fiber collimator 106 (i.e., the first output end P2); the s light first is reflected at the thin film connected by the two parallelogram crystals, then passes through the parallelogram crystal above, and is totally reflected at the interface between the parallelogram crystal and the external air, and finally is transmitted to the second single-fiber collimator 106 (i.e., the first output end P2).

[0056] As can be seen from the above principle, when the optical channel is switched, it is essentially the exchange of the intensity of the strong light and weak light paths. After deducting the material absorption, material reflectivity loss and coupling loss between parts, theoretically the sum of the energy of the two is equal to the input light energy. This solution couples both strong light and weak light into different channels (the magneto-optical switches currently on the market only couple strong light channels, not weak light channels). When the switch is switched, it actually takes a certain response time to complete the switch. During the time when the switch starts but is not completed, the energy of the weak light increases when the energy is converted between the strong light and the weak light. However, since the conventional magneto-optical switch does not couple the weak light channel, instability occurs in the system, and it will not stabilize until all switches are completed). In this invention, the sum of the energy at the P2+P3 channel and the sum of the energy of the P2+P3 channel after the switch is completed are always in a stable state, which brings stability to the network transmission.

[0057] The present application realizes lossless switching of magneto-optical switches. By cleverly arranging polarization beam splitters, half-wave plates and Faraday rotator crystals are used to change the polarization direction of the light beam, ensuring that all light beams can be accurately converged to the output end after passing through the second polarization beam splitter prism 105. This design greatly reduces the loss of light energy during the switching process of the optical switch, thereby achieving that the sum of the light energy output from the two ports of the magneto-optical switch remains constant throughout the entire process, whether at the moment of switching or after the switching is completed. This design can greatly reduce the energy loss generated by the magneto-optical switch during the switching process, and provide a high degree of stability for the optical transmission system.

[0058] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which are equivalent modifications and improvements made to the above embodiments based on the essential technology of the present invention, and all of them belong to the protection scope of the present invention.

Claims

1. A lossless switching magneto-optical switch, comprising an input end, a first output end and a second output end, characterized in that: The lossless switching magneto-optical switch also includes a first polarization beam splitter prism, a first half-wave plate, a Faraday rotator crystal and a second polarization beam splitter prism which are arranged in sequence. The input end is located on the side of the first polarization beam splitter prism away from the first half-wave plate, the first output end and the second output end are located on the side of the second polarization beam splitter prism away from the Faraday rotator crystal, the first polarization beam splitter prism and the second polarization beam splitter prism each include two crystals, the two crystals are coated at the joint, the first polarization beam splitter prism decomposes the parallel light input from the input end into two sub-beams p light and s light with orthogonal polarization directions, The p-light and the s-light are two main light paths, the first half-wave plate can rotate the polarization direction of the p-light by 135° clockwise along the light path transmission direction, and the polarization direction of the s-light can rotate by 45° counterclockwise along the light path transmission direction, the Faraday rotator crystal can rotate the main light path by 45° clockwise or 45° counterclockwise by applying magnetic fields in different directions, and at the same time, the polarization direction of a very weak light beam is not rotated to generate two weak light paths, and the second polarization beam splitter prism converges the p-light and the s-light of the two main light paths to the first output end or the second output end, and converges the p-light and the s-light of the two weak light paths to the other second output end or the first output end.

2. The magneto-optical switch for lossless switching according to claim 1, characterized in that: The two crystals of the first polarization beam splitter are respectively a parallelogram crystal and a triangular crystal, and the mating surfaces of the parallelogram crystal and the triangular crystal are coated with a film, and the film reflects the s light and transmits the p light.

3. The magneto-optical switch for lossless switching according to claim 2, characterized in that: The two crystals of the second polarization beam splitter prism are two parallelogram crystals respectively, and the bonding surfaces of the two parallelogram crystals are coated with a film, and the film reflects the S light.

4. The magneto-optical switch for lossless switching according to claim 3, characterized in that: The lossless switching magneto-optical switch also includes a second half-wave plate and a third half-wave plate, wherein the second half-wave plate is located between the first polarization beam splitter prism and the first half-wave plate, and the second half-wave plate is located on the p light channel emitted from the first polarization beam splitter prism, and the third half-wave plate is located between the Faraday rotator crystal and the second polarization beam splitter prism, and the third half-wave plate is located on the s light channel emitted from the first polarization beam splitter prism.

5. The magneto-optical switch for lossless switching according to claim 4, characterized in that: The position of the second half-wave plate corresponds to the triangular crystal of the first polarization beam splitter prism, and the position of the third half-wave plate corresponds to the parallelogram crystal of the first polarization beam splitter prism.

6. The magneto-optical switch for lossless switching according to claim 1, characterized in that: The lossless switching magneto-optical switch further comprises a first single-fiber collimator, which is located at the input end and collimates the divergent light beam output by the optical fiber into a parallel light beam.

7. The magneto-optical switch for lossless switching according to claim 6, characterized in that: The lossless switching magneto-optical switch further includes a second single fiber collimator and a third single fiber collimator, and the second single fiber collimator and the third single fiber collimator are respectively located at the first output end and the second output end.

8. The magneto-optical switch for lossless switching according to claim 7, characterized in that: The parallel light beam emitted by the first single-fiber collimator, the light beam received by the second single-fiber collimator, and the light beam received by the third single-fiber collimator are parallel to each other.

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