Bidirectional light-passing magneto-optical switch

Abstract

The invention provides a bidirectional light-passing magneto-optical switch, and relates to the technical field of optical communication, and the bidirectional light-passing magneto-optical switch comprises an input collimation unit, a first polarization processing unit, a polarization path selection unit, a second polarization processing unit, an output collimation unit and a magnetic field generation and control unit which are sequentially arranged along an optical path. According to the magneto-optical switch capable of achieving bidirectional light transmission, the 45-degree half-wave plate and the Faraday optical rotation crystal are reasonably configured, the polarization direction of light beams is regulated and controlled, and it is ensured that all the light beams can be accurately converged to the output end after passing through the birefringent crystal. The structure realizes bidirectional reversible transmission of an optical path, and is suitable for an application scene requiring bidirectional information interaction between channels.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and in particular to a bidirectional magneto-optical switch. Background Technology

[0002] In optical communication systems, optical switches, as core passive devices for optical path scheduling and protection, directly impact the network's flexibility and reliability. Magneto-optical switches are a type of non-mechanical optical switch based on the Faraday rotation effect. They achieve directional transmission of optical paths by controlling the direction of an applied magnetic field to change the Faraday rotation angle of polarized light in the magneto-optical crystal. Compared to traditional mechanical optical switches, these devices offer significant advantages such as microsecond-level switching speeds, no mechanical wear, and long lifespan, making them a crucial development direction for current optical switching technology.

[0003] Currently, most magneto-optical switches on the market operate with forward light transmission and reverse cutoff. Specifically, when an optical signal is transmitted from Port 1 to Port 2, the optical path from Port 2 to Port 1 is blocked; similarly, when an optical signal is transmitted from Port 1 to Port 3, the optical path from Port 3 to Port 1 is also blocked. Due to the irreversibility of the optical path, such magneto-optical switches are difficult to apply to applications requiring bidirectional information exchange between channels. Therefore, this paper proposes a magneto-optical switch with bidirectional light transmission capability.

[0004] To address the above problems, this invention proposes a bidirectional magneto-optical switch. Summary of the Invention

[0005] In order to achieve the above-mentioned objectives and other advantages of the present invention, the objective of the present invention is to provide a bidirectional optical magneto-optical switch, comprising an input collimation unit, a first polarization processing unit, a polarization path selection unit, a second polarization processing unit, an output collimation unit, and a magnetic field generation and control unit arranged sequentially along the optical path; The input collimation unit is used to collimate the input divergent beam into a parallel beam; The first polarization processing unit is disposed after the input collimation unit and is used to convert the incident parallel beam into two sub-beams with parallel polarization directions and to perform a first-stage polarization state rotation on them. The polarization path selection unit is located after the first polarization processing unit and is used to control whether the two sub-beams undergo spatial displacement based on the polarization state of the two sub-beams relative to their optical axes. The second polarization processing unit is disposed after the polarization path selection unit and is used to perform a second-stage polarization state rotation on the two sub-beams after path selection and adjust their polarization states to be mutually orthogonal. The output collimation unit is used to couple the beam that has been combined after being processed by the second polarization processing unit to different target output ports; The magnetic field generation and control unit controls the direction of the magnetic field applied to the first polarization processing unit and / or the second polarization processing unit, thereby changing the net polarization rotation angle of the two sub-beams before passing through the polarization path selection unit. This controls whether the two sub-beams undergo spatial displacement in the polarization path selection unit, and thus the final combined beam is guided to different output ports by the output collimation unit, achieving bidirectional optical path switching.

[0006] Furthermore, the input collimation unit is a single-fiber collimator; the output collimation unit is a dual-fiber collimator with two output ports; the input collimation unit and the output collimation unit are respectively placed on both sides of the optical switch, forming a transmissive structure.

[0007] Furthermore, it also includes a beam deflection unit, which is disposed between the polarization path selection unit and the second polarization processing unit, and is used to adjust the propagation direction of the beam to match the receiving angle of the output collimation unit; the beam deflection unit is preferably a roof prism.

[0008] Furthermore, the first polarization processing unit includes, along the optical path: a first birefringent crystal, a first half-wave plate, a first Faraday rotator crystal, and a second Faraday rotator crystal; The first birefringent crystal is used to decompose the incident parallel beam into two sub-beams with orthogonal polarization directions; The first half-wave plate partially covers the sub-beam path, which is used to rotate the polarization direction of one of the sub-beams by 90°, thereby making the polarization directions of the two sub-beams parallel. The first Faraday rotator crystal and the second Faraday rotator crystal are connected in series to perform polarization rotation on two parallel polarized sub-beams.

[0009] Furthermore, the polarization path selection unit is a second birefringent crystal, whose optical axis direction forms a specific angle with the optical axis direction of the first birefringent crystal.

[0010] Furthermore, the second polarization processing unit includes, along the optical path: a third Faraday rotator crystal, a fourth Faraday rotator crystal, and a second half-wave plate; The third and fourth Faraday rotator crystals are connected in series to perform polarization rotation on the two sub-beams; The second half-wave plate partially covers the sub-beam path, which rotates the polarization direction of one of the sub-beams by 90°, thereby restoring the polarization directions of the two sub-beams to orthogonality.

[0011] Furthermore, it also includes a beam combining unit, which is a third birefringent crystal, disposed between the second polarization processing unit and the output collimation unit, for combining two sub-beams with orthogonal polarization directions into a single beam.

[0012] Furthermore, the magnetic field generating and control unit includes: The first permanent magnet and the second permanent magnet are respectively used to apply a constant magnetic field in a fixed direction to the first Faraday rotator crystal and the fourth Faraday rotator crystal, so that they produce a fixed polarization rotation. An electromagnetic coil generates a magnetic field that acts simultaneously on the second and third Faraday rotator crystals. By changing the direction of the current flowing through it, the polarization rotation direction of the two Faraday rotator crystals is controlled synchronously. The first magnetic shielding structure and the second magnetic shielding structure are used to isolate the magnetic fields generated by the first permanent magnet, the second permanent magnet and the electromagnetic coil, respectively, to prevent mutual interference.

[0013] Furthermore, under the action of a constant magnetic field, both the first and fourth Faraday rotator crystals cause the polarization state of the light beam to rotate clockwise by 45°; when the electromagnetic coil is energized with a current in the first direction, the second and third Faraday rotator crystals cause the polarization state of the light beam to rotate counterclockwise by 45°, and when energized with a current in the opposite direction, they cause the polarization state of the light beam to rotate clockwise by 45°; when no current is energized, the polarization state of the light beam is rotated in the direction of the last energized current.

[0014] Furthermore, the port of the single-fiber collimator is defined as port one, and the two ports of the dual-fiber collimator are defined as port two and port three, respectively; by controlling the current direction of the electromagnetic coil, the magneto-optical switch can be switched between the following two bidirectional light-transmitting states: State A: Bidirectional connectivity between port 1 and port 2; State B: Bidirectional connection between port 1 and port 3.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a magneto-optical switch capable of bidirectional light transmission. By rationally configuring a 45° half-wave plate and a Faraday rotator crystal, the polarization direction of the light beam is controlled, ensuring that all beams are accurately converged to the output end after passing through the birefringent crystal. This structure achieves bidirectional reversible transmission of the optical path and is suitable for applications requiring bidirectional information exchange between channels.

[0016] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments of the present invention are given in detail below with reference to the accompanying drawings. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a structural diagram of a bidirectional magneto-optical switch. Figure 2 This is a diagram of the external structure of a bidirectional magneto-optical switch. Figure 3 A top view of the bidirectional magneto-optical switch in operation; Figure 4 This is a side view of the magneto-optical switch when it is operating with bidirectional connectivity between Port 1 and Port 2. Figure 5 This is the polarization pattern of the light beam after passing through each optical element when Port 1 to Port 2 are connected; Figure 6 This is the beam polarization pattern after passing through each optical element when Port 2 to Port 1 is connected; Figure 7 This is a side view of the magneto-optical switch when it is operating with bidirectional connectivity between Port 1 and Port 3. Figure 8 This is the polarization pattern of the light beam after passing through each optical element when Port 1 to Port 3 are connected; Figure 9 This is the polarization pattern of the light beam after passing through each optical element when Port 3 to Port 1 is connected.

[0018] In the diagram: 101, single-fiber collimator; 102, first birefringent crystal; 103, first half-wave plate; 104, first Faraday rotator crystal; 105, second Faraday rotator crystal; 106, second birefringent crystal; 107, third Faraday rotator crystal; 108, fourth Faraday rotator crystal; 109, roof prism; 110, second half-wave plate; 111, third birefringent crystal; 112, dual-fiber collimator; 201, first permanent magnet; 202, first magnetic shielding structure; 203, electromagnetic coil; 204, second magnetic shielding structure; 205, second permanent magnet. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the accompanying drawings, shapes and dimensions may be enlarged for clarity, and the same reference numerals will be used in all figures to indicate the same or similar parts.

[0021] In the following description, terms such as center, thickness, height, length, front, back, rear, left, right, top, bottom, upper, and lower are defined relative to the structure shown in the accompanying drawings. In particular, "height" corresponds to the dimension from top to bottom, "width" corresponds to the dimension from left to right, and "depth" corresponds to the dimension from front to back. These are relative concepts and may vary depending on their location and usage. Therefore, these or other orientations should not be interpreted as restrictive terms.

[0022] Terms involving attachment, connection, etc. (e.g., “connection” and “attachment”) refer to the relationship in which these structures are directly or indirectly fixed or attached to each other through an intermediate structure, as well as movable or rigid attachments or relationships, unless otherwise explicitly stated.

[0023] This invention provides a bidirectional magneto-optical switch to solve the problem of irreversible optical path in existing magneto-optical switches.

[0024] To achieve the above objectives, this invention provides a bidirectional magneto-optical switch employing components such as an fiber collimator, a roof prism, a birefringent crystal, a zero-order half-wave plate, and a Faraday rotator crystal. The specific implementation process is as follows: The light beam input from the fiber is first collimated into a parallel beam by the fiber collimator. Then, this parallel beam is separated into two sub-beams with fixed polarization states by the birefringent crystal. Next, the polarization states of these sub-beams are processed and changed using a 45° half-wave plate and a Faraday rotator crystal. By further combining the birefringent crystal for beam splitting and pairing the roof prism with the dual-fiber collimator, a bidirectional magneto-optical switch is finally realized. The specific scheme is as follows: Example 1 A bidirectional magneto-optical switch, such as Figures 1-9 As shown, it includes an input collimation unit, a first polarization processing unit, a polarization path selection unit, a second polarization processing unit, an output collimation unit, and a magnetic field generation and control unit arranged sequentially along the optical path; The input collimation unit is used to collimate the input divergent beam into a parallel beam; The first polarization processing unit is disposed after the input collimation unit and is used to convert the incident parallel beam into two sub-beams with parallel polarization directions and to perform a first-stage polarization state rotation on them. The polarization path selection unit is located after the first polarization processing unit and is used to control whether the two sub-beams undergo spatial displacement based on the polarization state of the two sub-beams relative to their optical axes. The second polarization processing unit is disposed after the polarization path selection unit and is used to perform a second-stage polarization state rotation on the two sub-beams after path selection and adjust their polarization states to be mutually orthogonal. The output collimation unit is used to couple the beam that has been combined after being processed by the second polarization processing unit to different target output ports; The magnetic field generation and control unit controls the direction of the magnetic field applied to the first polarization processing unit and / or the second polarization processing unit, thereby changing the net polarization rotation angle of the two sub-beams before passing through the polarization path selection unit. This controls whether the two sub-beams undergo spatial displacement in the polarization path selection unit, and thus the final combined beam is guided to different output ports by the output collimation unit, achieving bidirectional optical path switching.

[0025] like Figure 1 , Figure 3 , Figure 4 , Figure 7 As shown, the input collimation unit is a single-fiber collimator 101; the output collimation unit is a dual-fiber collimator 112, which has two output ports; the input collimation unit and the output collimation unit are respectively placed on both sides of the optical switch, forming a transmissive structure.

[0026] In some embodiments, a beam deflection unit is further included, which is disposed between the polarization path selection unit and the second polarization processing unit, and is used to adjust the propagation direction of the beam to match the receiving angle of the output collimation unit; the beam deflection unit is preferably a roof prism 109.

[0027] The first polarization processing unit includes, along the optical path: a first birefringent crystal 102, a first half-wave plate 103, a first Faraday rotator crystal 104, and a second Faraday rotator crystal 105; The first birefringent crystal 102 is used to decompose the incident parallel beam into two sub-beams with orthogonal polarization directions; The first half-wave plate 103 partially covers the sub-beam path, which is used to rotate the polarization direction of one of the sub-beams by 90°, thereby making the polarization directions of the two sub-beams parallel. The first Faraday rotator crystal 104 and the second Faraday rotator crystal 105 are connected in series to perform polarization rotation on two parallel polarized sub-beams.

[0028] The polarization path selection unit is a second birefringent crystal 106, whose optical axis direction forms a specific angle with the optical axis direction of the first birefringent crystal 102.

[0029] The second polarization processing unit includes, along the optical path: a third Faraday rotator crystal 107, a fourth Faraday rotator crystal 108, and a second half-wave plate 110; The third Faraday rotator crystal 107 and the fourth Faraday rotator crystal 108 are connected in series to perform polarization rotation on the two sub-beams; The second half-wave plate 110 partially covers the sub-beam path to rotate the polarization direction of one of the sub-beams by 90°, thereby restoring the polarization directions of the two sub-beams to orthogonal.

[0030] Furthermore, both the first and second half-wave plates are 45° half-wave plates.

[0031] In some embodiments, a beam combining unit is further included, wherein the beam combining unit is a third birefringent crystal 111, which is disposed between the second polarization processing unit and the output collimation unit, for combining two sub-beams with orthogonal polarization directions into a single beam.

[0032] like Figure 2 As shown, the magnetic field generating and control unit includes: The first permanent magnet 201 and the second permanent magnet 205 are respectively used to apply a constant magnetic field in a fixed direction to the first Faraday optical rotator crystal 104 and the fourth Faraday optical rotator crystal 108, so that they produce a fixed polarization rotation. The electromagnetic coil 203 generates a magnetic field that acts simultaneously on the second Faraday rotator crystal 105 and the third Faraday rotator crystal 107. By changing the direction of the current, the polarization rotation direction of the two Faraday rotator crystals is synchronously controlled. In this embodiment, the electromagnetic coil is a self-adhesive coil. The self-adhesive coil 203 controls the polarization rotation of the second Faraday rotator crystal 105 and the third Faraday rotator crystal 107 synchronously by changing the direction of the magnetic field.

[0033] The first magnetic shielding structure 202 and the second magnetic shielding structure 204 are used to isolate the magnetic fields generated by the first permanent magnet 201, the second permanent magnet 205 and the electromagnetic coil 203, respectively, to prevent them from interfering with the adjacent Faraday optical rotator crystal.

[0034] The first permanent magnet 201 and the second permanent magnet 205 apply constant magnetic fields to the first Faraday rotator crystal 104 and the fourth Faraday rotator crystal 108, respectively. When observed in the direction of a single-fiber collimator, the first Faraday rotator crystal 104 and the fourth Faraday rotator crystal 108, under the action of constant magnetic fields, both cause the polarization state of the light beam to rotate clockwise by 45°. When the electromagnetic coil 203 is energized with a current in the first direction, the second Faraday rotator crystal 105 and the third Faraday rotator crystal 107 cause the polarization state of the light beam to rotate counterclockwise by 45°. When an opposite current is energized, the polarization state of the light beam rotates clockwise by 45°. When no current is energized, the polarization state of the light beam rotates in the direction of the last energized current.

[0035] The port of the single-fiber collimator 101 is defined as Port 1, and the two ports of the dual-fiber collimator 112 are defined as Port 2 and Port 3, respectively. By controlling the current direction of the electromagnetic coil 203, the magneto-optical switch can be switched between the following two bidirectional light-transmitting states: State A: Bidirectional connectivity between port 1 and port 2; State B: Bidirectional connection between port 1 and port 3.

[0036] When the magneto-optical switch is operating in the Port 1 to Port 2 optical path channel: the side view of the magneto-optical switch at this time is as follows. Figure 4 As shown, when observed from the direction of the single-fiber collimator, with Port 1 to Port 2 connected, the polarization direction of the beam after passing through each optical element is as follows: Figure 5 As shown: The diverging beam output from the optical fiber is first collimated into a parallel beam by a single-fiber collimator 101. After passing through the first birefringent crystal 102, the parallel beam is decomposed into two sub-beams with orthogonal polarization directions. After passing through the first half-wave plate 103, the sub-beam propagating along the left side does not pass through the 45° half-wave plate, so the polarization direction does not rotate. The sub-beam propagating along the right side passes through the 45° half-wave plate, and the polarization direction rotates 90° along the light propagation direction. At this time, the polarization directions of the two sub-beams change to a state of being parallel to each other. After passing through the first Faraday rotator crystal 104, the polarization direction of the two sub-beams rotates 45° clockwise along the light transmission direction; After passing through the second Faraday rotator crystal 105, the polarization direction of the two sub-beams rotates counterclockwise by 45° along the light transmission direction. After passing through the second birefringent crystal 106, both sub-beams are ordinary light (o-rays), so the two sub-beams will not deviate and will continue to propagate in a straight line. After passing through the third Faraday rotator crystal 107, the polarization direction of the two sub-beams rotates counterclockwise by 45° along the light transmission direction. After passing through the fourth Faraday rotator crystal 108, the polarization direction of the two sub-beams rotates 45° clockwise along the light transmission direction. After passing through the roof prism 109, the exit angle of the light beam changes, and the light is deflected downwards to match the exit angle of the dual-fiber collimator 112. After passing through the second half-wave plate 110, the sub-beam propagating along the left side passes through the 45° half-wave plate, and its polarization direction rotates 90° along the light propagation direction. The sub-beam propagating along the right side passes through the 45° half-wave plate, so its polarization direction does not rotate. After passing through the third birefringent crystal 111, the two sub-beams of the main ray with orthogonal polarization directions recombined and entered the Port 2 port of the dual-fiber collimator 112; When the magneto-optical switch is operating in the Port 2 to Port 1 optical path channel: the side view of the magneto-optical switch at this time is as follows. Figure 4 As shown, when observed from the direction of the single-fiber collimator, with Port 2 to Port 1 connected, the polarization direction of the beam after passing through each optical element is as follows: Figure 6 As shown: The diverging beam output from the optical fiber is first collimated into a beam with a certain incident angle through Port 2 of the dual-fiber collimator 112, and the beam propagates upward. After passing through the third birefringent crystal 111, the parallel beam is decomposed into two sub-beams with orthogonal polarization directions. After passing through the second half-wave plate 110, the sub-beam propagating along the left passes through the 45° half-wave plate, and its polarization direction rotates 90° along the light propagation direction. The sub-beam propagating along the right does not pass through the 45° half-wave plate, so its polarization direction does not rotate. At this time, the polarization directions of the two sub-beams change to a state of being parallel to each other. After passing through the roof prism 109, the angled beam of light is deflected into a parallel beam and then propagates in a straight line. After passing through the fourth Faraday rotator crystal 108, the polarization direction of the two sub-beams rotates 45° clockwise along the light transmission direction. After passing through the third Faraday rotator crystal 107, the polarization direction of the two sub-beams rotates counterclockwise by 45° along the light transmission direction. After passing through the second birefringent crystal 106, both sub-beams are ordinary light (o-rays), so the two sub-beams will not deviate and will continue to propagate in a straight line. After passing through the second Faraday rotator crystal 105, the polarization direction of the two sub-beams rotates counterclockwise by 45° along the light transmission direction. After passing through the first Faraday rotator crystal 104, the polarization direction of the two sub-beams rotates 45° clockwise along the light transmission direction; After passing through the first half-wave plate 103, the sub-beam propagating along the left side passes through the 45° half-wave plate, so the polarization direction does not rotate. The sub-beam propagating along the right side passes through the 45° half-wave plate, and the polarization direction rotates 90° along the light propagation direction. After passing through the first birefringent crystal 102, the two sub-beams of the main ray with orthogonal polarization directions recombined and entered the single-fiber collimator 101.

[0037] When the magneto-optical switch is operating in the optical path channel from Port 1 to Port 3: the side view of the magneto-optical switch at this time is as follows. Figure 7 As shown, when observed from the direction of the single-fiber collimator, with Port 1 to Port 3 connected, the polarization direction of the beam after passing through each optical element is as follows: Figure 8 As shown: The diverging beam output from the optical fiber is first collimated into a parallel beam by a single-fiber collimator 101. After passing through the first birefringent crystal 102, the parallel beam is decomposed into two sub-beams with orthogonal polarization directions. After passing through the first half-wave plate 103, the sub-beam propagating along the left side does not pass through the 45° half-wave plate, so the polarization direction does not rotate. The sub-beam propagating along the right side passes through the 45° half-wave plate, and the polarization direction rotates 90° along the light propagation direction. At this time, the polarization directions of the two sub-beams change to a state of being parallel to each other. After passing through the first Faraday rotator crystal 104, the polarization direction of the two sub-beams rotates 45° clockwise along the light transmission direction; After passing through the second Faraday rotator crystal 105, the polarization direction of the two sub-beams rotates 45° clockwise along the light transmission direction; After passing through the second birefringent crystal 106, both sub-beams are extraordinary e-beams. Therefore, both sub-beams are deflected along the optical axis of the second birefringent crystal and then continue to propagate in a straight line. After passing through the third Faraday rotator crystal 107, the polarization direction of the two sub-beams rotates 45° clockwise along the light transmission direction; After passing through the fourth Faraday rotator crystal 108, the polarization direction of the two sub-beams rotates 45° clockwise along the light transmission direction. After passing through the roof prism 109, the exit angle of the light beam changes, and the light is deflected downwards to match the exit angle of the dual-fiber collimator 112. After passing through the second half-wave plate 110, the sub-beam propagating along the left side passes through the 45° half-wave plate, and its polarization direction rotates 90° along the light propagation direction. The sub-beam propagating along the right side passes through the 45° half-wave plate, so its polarization direction does not rotate. After passing through the third birefringent crystal 111, the two sub-beams of the main ray with orthogonal polarization directions recombined and entered the Port 3 port of the dual-fiber collimator 112; When the magneto-optical switch is operating in the Port 3 to Port 1 optical path channel: The side view of the magneto-optical switch at this time is as follows. Figure 7 As shown, when observed from the direction of the single-fiber collimator, with Port 3 to Port 1 connected, the polarization direction of the beam after passing through each optical element is as follows: Figure 9 As shown: The diverging beam output from the optical fiber is first collimated into a beam with a certain incident angle through the Port 3 port of the dual-fiber collimator 112, and the beam propagates upward. After passing through the third birefringent crystal 111, the parallel beam is decomposed into two sub-beams with orthogonal polarization directions. After passing through the second half-wave plate 110, the sub-beam propagating along the left passes through the 45° half-wave plate, and its polarization direction rotates 90° along the light propagation direction. The sub-beam propagating along the right does not pass through the 45° half-wave plate, so its polarization direction does not rotate. At this time, the polarization directions of the two sub-beams change to a state of being parallel to each other. After passing through the roof prism 109, the angled beam of light is deflected into a parallel beam and then propagates in a straight line. After passing through the fourth Faraday rotator crystal 108, the polarization direction of the two sub-beams rotates 45° clockwise along the light transmission direction. After passing through the third Faraday rotator crystal 107, the polarization direction of the two sub-beams rotates counterclockwise by 45° along the light transmission direction. After passing through the second birefringent crystal 106, both sub-beams are extraordinary e-beams. Therefore, the two sub-beams are deflected along the optical axis of the second birefringent crystal and then continue to propagate in a straight line. After passing through the second Faraday rotator crystal 105, the polarization direction of the two sub-beams rotates 45° clockwise along the light transmission direction; After passing through the first Faraday rotator crystal 104, the polarization direction of the two sub-beams rotates 45° clockwise along the light transmission direction; After passing through the first half-wave plate 103, the sub-beam propagating along the left side passes through the 45° half-wave plate, so the polarization direction does not rotate. The sub-beam propagating along the right side passes through the 45° half-wave plate, and the polarization direction rotates 90° along the light propagation direction. After passing through the first birefringent crystal 102, the two sub-beams of the main ray with orthogonal polarization directions recombined and entered the single-fiber collimator 101.

[0038] Based on the above principle, when the magneto-optical switch is in the operating state of Port 1 to Port 2, the optical signal can be transmitted simultaneously from Port 2 to Port 1; when the magneto-optical switch is in the operating state of Port 1 to Port 3, the optical signal can also be transmitted simultaneously from Port 3 to Port 1. The magnetic shield is used to shield the magnetic field generated by the permanent magnet and the self-adhesive coil, preventing it from interfering with adjacent Faraday-rotating crystals. By applying a positive or negative voltage to a single self-adhesive coil, the operating channel of the magneto-optical switch can be switched, thereby achieving the function of controlling the optical path switching using a single coil.

[0039] This invention provides a bidirectional magneto-optical switch. The switch employs a transmissive structure and utilizes a switchable polarization path selection unit and a single coil to synchronously control two Faraday rotator crystals, achieving bidirectional, low-crosstalk optical path switching between single-fiber and dual-fiber configurations.

[0040] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A bidirectional transmissive magneto-optical photo switch, characterized by, The input collimation unit, the first polarization processing unit, the polarization path selection unit, the second polarization processing unit and the output collimation unit are arranged in sequence along the light path, and a magnetic field generating and control unit is arranged; The input collimation unit is used for collimating the input divergent light beam into a parallel light beam; The first polarization processing unit is arranged after the input collimation unit and is used for converting the incident parallel light beam into two sub-beams with parallel polarization directions and performing first-stage polarization state rotation on the two sub-beams; The polarization path selection unit is arranged after the first polarization processing unit and is used for controlling whether the two sub-beams are spatially displaced according to the direction of the polarization state of the two sub-beams relative to the optical axis thereof; The second polarization processing unit is arranged after the polarization path selection unit and is used for performing second-stage polarization state rotation on the two sub-beams after the path selection and adjusting the polarization states of the two sub-beams to be orthogonal to each other; The output collimation unit is used for coupling the combined light beam after the processing of the second polarization processing unit to different target output ports; The magnetic field generating and control unit controls the direction of the magnetic field applied to the first polarization processing unit and / or the second polarization processing unit, changes the net polarization rotation angle of the two sub-beams before passing through the polarization path selection unit, controls whether the two sub-beams are spatially displaced in the polarization path selection unit, and then makes the finally combined light beam be guided to different output ports by the output collimation unit, thereby realizing bidirectional light path switching.

2. A bi-directional transmissive magneto-optical optical switch as claimed in claim 1, characterized in that, The input collimation unit is a single-fiber collimator, the output collimation unit is a double-fiber collimator with two output ports, and the input collimation unit and the output collimation unit are arranged on the two sides of the optical switch to form a transmission structure.

3. A bi-directional transmissive magneto-optical optical switch as claimed in claim 2, characterized in that, The optical beam folding unit is arranged between the polarization path selection unit and the second polarization processing unit and is used for adjusting the propagation direction of the light beam to match the receiving angle of the output collimation unit; the optical beam folding unit is preferably a roof prism.

4. A bi-directional transmissive magneto-optical optical switch as claimed in claim 3, characterized in that, The first polarization processing unit includes a first birefringent crystal, a first half-wave plate, a first Faraday optical rotatory crystal and a second Faraday optical rotatory crystal along the light path; The first birefringent crystal is used for decomposing the incident parallel light beam into two sub-beams with orthogonal polarization directions; The first half-wave plate partially covers the sub-beam path and is used for rotating the polarization direction of one of the two sub-beams by 90°, so that the polarization directions of the two sub-beams become parallel; The first Faraday optical rotatory crystal and the second Faraday optical rotatory crystal are arranged in series and are used for performing polarization rotation on the two parallel polarized sub-beams.

5. A bi-directional transmissive magneto-optical optical switch as claimed in claim 4, characterized in that, The polarization path selection unit is a second birefringent crystal, and the optical axis direction of the second birefringent crystal forms a specific angle with the optical axis direction of the first birefringent crystal.

6. A bi-directional transmissive magneto-optical optical switch as claimed in claim 5, characterized in that, The second polarization processing unit includes a third Faraday optical rotatory crystal, a fourth Faraday optical rotatory crystal and a second half-wave plate along the light path; The third Faraday optical rotatory crystal and the fourth Faraday optical rotatory crystal are arranged in series and are used for performing polarization rotation on the two sub-beams; The second half-wave plate partially covers the sub-beam path, and is used for rotating the polarization direction of one of the two sub-beams by 90°, so that the polarization directions of the two sub-beams are restored to be orthogonal.

7. A bi-directional transmissive magneto-optical optical switch as claimed in claim 6, characterized in that The beam combining unit is a third birefringent crystal, which is arranged between the second polarization processing unit and the output collimator, and is used for combining the two sub-beams with orthogonal polarization directions into one beam.

8. A bi-directional transmissive magneto-optical optical switch as claimed in claim 7, characterized in that, The magnetic field generating and control unit comprises: The first permanent magnet and the second permanent magnet are respectively used for applying a constant magnetic field with a fixed direction to the first Faraday optical rotator and the fourth Faraday optical rotator, so that they generate a fixed polarization rotation; The electromagnetic coil generates a magnetic field acting on the second Faraday optical rotator and the third Faraday optical rotator, and by changing the direction of the current, the polarization rotation directions of the two Faraday optical rotators are synchronously controlled; The first magnetic shielding structure and the second magnetic shielding structure are respectively used for isolating the magnetic fields generated by the first permanent magnet, the second permanent magnet and the electromagnetic coil, and preventing mutual interference.

9. A bi-directional transmissive magneto-optical optical switch as claimed in claim 8, characterized in that, The first Faraday optical rotator and the fourth Faraday optical rotator both rotate the polarization state of the light beam clockwise by 45° under the action of the constant magnetic field; when the electromagnetic coil is supplied with a current in the first direction, the second Faraday optical rotator and the third Faraday optical rotator rotate the polarization state of the light beam counterclockwise by 45°, when the current is supplied in the opposite direction, the polarization state of the light beam is rotated clockwise by 45°, and when there is no current, the polarization state of the light beam is rotated according to the direction of the last current.

10. A bi-directional transmissive magneto-optical optical switch as claimed in claim 9, characterized in that, The port of the single-fiber collimator is defined as port one, and the two ports of the double-fiber collimator are defined as port two and port three respectively; by controlling the current direction of the electromagnetic coil, the magneto-optical switch is switched between the following two bidirectional light transmission states: State A: bidirectional communication between port one and port two; State B: bidirectional communication between port one and port three.

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