Lossless switching structure of magneto-optical switch

Abstract

The invention discloses a magneto-optical switch lossless switching structure, which belongs to the field of optical elements, and comprises a first birefringent crystal, a first wave plate assembly, a Faraday optical rotation crystal, a second birefringent crystal, a second wave plate assembly, a third wave plate assembly and a third birefringent crystal which are arranged in sequence, the first output end and the second output end are located on one side of the third birefringent crystal, the main sub light beams and the weak sub light beams can be accurately converged to the output ends by adopting the multiple wave plate assemblies, when optical channels are switched, intensities on the paths of the strong light rays and the weak light rays are essentially exchanged, the strong light rays and the weak light rays are coupled into different channels, and therefore the light intensity is greatly improved. 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 structure of a 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 lossless switching structure 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 magneto-optical switch lossless switching structure comprises a single-fiber collimator, a first birefringent crystal, a first wave plate assembly, a Faraday rotator crystal, a second birefringent crystal, a second wave plate assembly, a third wave plate assembly and a third birefringent crystal arranged in sequence, wherein the single-fiber collimator is located on a side of the first birefringent crystal away from the first wave plate assembly, and the magneto-optical switch lossless switching structure is provided with an input end, a first output end and a second output end, wherein the input end is located on one side of the single-fiber collimator, and the first output end and the second output end are located on one side of the third birefringent crystal.

[0007] The parallel light beam emitted by the single-fiber collimator is decomposed into two main sub-beams with orthogonal polarization directions by the first birefringent crystal, and the polarization directions of the two main sub-beams are changed to be parallel to each other after passing through the first wave plate assembly;

[0008] When the optical path from the input end to the first output end is working, the polarization directions of the two main sub-beams with mutually parallel polarization directions rotate counterclockwise after passing through the Faraday rotator crystal and generate two weak sub-beams, the two main sub-beams do not deviate when passing through the second birefringent crystal, the two weak sub-beams deviate when passing through the second birefringent crystal, the two main sub-beams rotate counterclockwise when passing through the upper area of ​​the second wave plate component, the two weak sub-beams rotate counterclockwise when passing through the lower area of ​​the second wave plate component, the polarization directions of the two main sub-beams and the two weak sub-beams are changed to be orthogonal to each other when passing through the third wave plate component, the two main sub-beams combine to enter the first output end when passing through the third birefringent crystal, and the two weak sub-beams combine to enter the second output end;

[0009] When the optical path channel from the input end to the second output end is working, the polarization directions of the two main sub-beams with mutually parallel polarization directions rotate clockwise after passing through the Faraday rotator crystal and generate two weak sub-beams, the two main sub-beams are offset after passing through the second birefringent crystal, and the two weak sub-beams are not offset after passing through the second birefringent crystal, the two main sub-beams rotate counterclockwise when passing through the lower area of ​​the second wave plate component, and the two weak sub-beams rotate counterclockwise when passing through the upper area of ​​the second wave plate component, and the polarization directions of the two main sub-beams and the two weak sub-beams are changed to be orthogonal to each other when passing through the third wave plate component, and the two main sub-beams and the two weak sub-beams are combined to enter the second output end when passing through the third birefringent crystal, and the two weak sub-beams are combined to enter the first output end.

[0010] Furthermore, the first wave plate assembly includes two half-wave plates, which are arranged on the left and right, and have different optical axes.

[0011] Furthermore, the optical axes of the two wave plates are arranged at an angle of 45° or 135° to each other.

[0012] Furthermore, the second wave plate assembly includes two half-wave plates, which are arranged one above the other and have different optical axes.

[0013] Furthermore, the optical axis angles between the upper and lower wave plates are arranged to be 45° or 135° to each other.

[0014] Furthermore, when the optical path channel from the input end to the first output end is working, the two main sub-beams are ordinary light when passing through the Faraday rotator crystal, and the two weak sub-beams generated are extraordinary light; when the optical path channel from the input end to the second output end is working, the two main sub-beams are extraordinary light when passing through the Faraday rotator crystal, and the two weak sub-beams generated are ordinary light.

[0015] Furthermore, the Faraday rotator crystal rotates the polarization direction at an angle of 45°.

[0016] Furthermore, the second wave plate assembly rotates the polarization directions of the main sub-beam and the weak sub-beam at different angles.

[0017] Furthermore, when the optical path channel from the input end to the first output end is working, the polarization directions of the two main sub-beams are rotated 45° counterclockwise when viewed along the optical path transmission direction, and the polarization directions of the two weak sub-beams are rotated 135° counterclockwise when viewed along the optical path transmission direction; when the optical path channel from the input end to the second output end is working, the polarization directions of the two main sub-beams are rotated 135° counterclockwise when viewed along the optical path transmission direction, and the polarization directions of the two weak sub-beams are rotated 45° counterclockwise when viewed along the optical path transmission direction.

[0018] Furthermore, the magneto-optical switch lossless switching structure also includes a roof prism and a dual-fiber output collimator, the roof prism is located between the second wave plate assembly and the third wave plate assembly, and the dual-fiber output collimator is located between the third birefringent crystal and the first output end and the second output end.

[0019] Compared with the prior art, the magneto-optical switch lossless switching structure of the present invention comprises a first birefringent crystal, a first wave plate assembly, a Faraday rotator crystal, a second birefringent crystal, a second wave plate assembly, a third wave plate assembly and a third birefringent crystal which are arranged in sequence, the single-fiber collimator is located on the side of the first birefringent crystal away from the first wave plate assembly, the magneto-optical switch lossless switching structure is provided with an input end, a first output end and a second output end, the input end is located on one side of the single-fiber collimator, the first output end and the second output end are located on one side of the third birefringent crystal, and by adopting a plurality of wave plate assemblies, it is ensured that all light beams (main sub-beams and weak sub-beams) can be accurately converged to the output end after passing through the third birefringent crystal, and when the light passes through the third birefringent crystal, the light beams (main sub-beams and weak sub-beams) can be accurately converged to the output end. When the channel is switched, it is essentially the exchange of the intensity of the strong light and weak light paths, coupling both the strong light and weak light into different 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, 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 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 switch is completed are always in a stable state, which brings stability to the network transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A three-dimensional diagram of the lossless switching structure of the magneto-optical switch of the present invention;

[0021] Figure 2 for Figure 1 A side view of the optical path of the lossless switching structure of the magneto-optical switch;

[0022] Figure 3 for Figure 1 A top view of the optical path of the lossless switching structure of the magneto-optical switch;

[0023] Figure 4 for Figure 1 A polarization direction diagram of a light beam when the magneto-optical switch lossless switching structure is working from the input end to the first output end;

[0024] Figure 5 for Figure 1 Polarization direction diagram of the light beam when the magneto-optical switch lossless switching structure works from the input end to the second output end.

[0025] In the figure: 101, single-fiber collimator; 102, first birefringent crystal; 103, first wave plate assembly; 104, Faraday rotator crystal; 105, second birefringent crystal; 106, second wave plate assembly; 107, roof prism; 108, third wave plate assembly; 109, third birefringent crystal; 110, dual-fiber output collimator. DETAILED DESCRIPTION

[0026] 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.

[0027] 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.

[0028] 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.

[0029] See also Figure 1 The lossless switching structure of the magneto-optical switch includes a single-fiber collimator 101, a first birefringent crystal 102, a first wave plate assembly 103, a Faraday rotator crystal 104, a second birefringent crystal 105, a second wave plate assembly 106, a roof prism 107, a third wave plate assembly 108, a third birefringent crystal 109 and a dual-fiber output collimator 110, which are arranged in sequence.

[0030] The single fiber collimator 101 is used to collimate the incident light at the input end into a parallel light beam.

[0031] The first birefringent crystal 102 is used to decompose the parallel light beam into two sub-beams with orthogonal polarization directions.

[0032] The first wave plate assembly 103 is used to change the polarization directions of the two sub-beams to a state parallel to each other. Specifically, the first wave plate assembly 103 includes two half-wave plates, which are arranged on the left and right, and the optical axes of the two half-wave plates are different. The optical axis angles between the two wave plates are placed at 45° or 135° to each other. Preferably, in this embodiment, the optical axis of the wave plate on the left is +67.5°, and the optical axis of the wave plate on the right is -67.5°

[0033] The Faraday rotator crystal 104 controls the operation of different channels of the magneto-optical switch by connecting different positive and negative poles of the voltage, thereby changing the direction of the magnetic field. The Faraday rotator crystal 104 rotates the polarization direction of the sub-beam.

[0034] The second birefringent crystal 105 is used to deviate the extraordinary light along the optical axis.

[0035] The second wave plate assembly 106 includes two half-wave plates, which are arranged up and down, and the optical axes of the two half-wave plates are different. The optical axis angles between the two wave plates are placed at 45° or 135° to each other. Preferably, in this embodiment, the optical axis direction of the upper 1 / 2 wave plate is in the direction of +22.5°, and the optical axis direction of the lower 1 / 2 wave plate is in the direction of -22.5°.

[0036] The roof prism 107 changes the emission angle of the light beam passing through to match the emission angle of the dual-fiber output collimator 110 .

[0037] The third wave plate assembly 108 changes the polarization directions of the two sub-beams of the main light to be orthogonal to each other, and the polarization directions of the two sub-beams of the weak light are also changed to be orthogonal to each other. The third wave plate assembly 108 includes two half-wave plates, which are arranged on the left and right, and the optical axes of the two half-wave plates are different. The optical axis angles between the two wave plates are placed at 45° or 135° to each other. Preferably, in this embodiment, the optical axis of the wave plate on the left is +67.5°, and the optical axis of the wave plate on the right is -67.5°

[0038] The third birefringent crystal 109 is used to combine the two sub-beams of the principal light with orthogonal polarization directions into one output end, and to combine the two sub-beams of the weak light with orthogonal polarization directions into the other output end.

[0039] The dual-fiber output collimator 110 is used to focus parallel light to be received in the optical fiber or to collimate the output light in the optical fiber into a parallel light beam.

[0040] An input end P1 is disposed on one side of the single-fiber collimator 101 , and a first output end P2 and a second output end P3 are disposed on the other side of the dual-fiber output collimator 110 .

[0041] Please continue reading Figure 2 , Figure 3 as well as Figure 4 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 polarization direction of the light beam after passing through each optical element is as follows Figure 4 shown.

[0042] The divergent light beam outputted by the optical fiber is first collimated into a parallel light beam by a single-fiber collimator 101; after the parallel light beam passes through the first birefringent crystal 102, the parallel light beam is decomposed into two main sub-beams with orthogonal polarization directions; after passing through the first wave plate assembly 103, the polarization directions of the two main sub-beams are changed to be parallel to each other; after passing through the Faraday rotator crystal 104, the polarization directions of the two main sub-beams are rotated by 45°. When the magneto-optical switch is in the P1->P2 optical path channel, the magnetic field direction is along the optical path transmission direction, and the polarization directions of the two main sub-beams are along the optical path transmission direction. Looking in the direction of the light source, the light source rotates 45° counterclockwise. With respect to the second birefringent crystal 105, at this time, both main sub-beams are ordinary light. Due to the correlation between the extinction ratio and the wavelength of the Faraday rotatory crystal 104, not 100% of the energy is concentrated in the ordinary light (main sub-beam) state, and some very weak light energy is concentrated in the extraordinary light state (i.e., two weak sub-beams are generated). After passing through the second birefringent crystal 105, both main sub-beams are ordinary light, and the light will not be offset. However, both weak sub-beams are extraordinary light, and the light will be offset along the optical axis. Figure 4The red font polarization mark in the figure; after passing through the second wave plate component 106, the polarization directions of the two main sub-beams are rotated 45° counterclockwise when viewed along the optical path transmission direction, and the polarization directions of the two weak sub-beams are rotated 135° counterclockwise when viewed along the optical path transmission direction; after passing through the roof prism 107, the emission angle of the light beam changes to match the light emission angle of the dual-fiber collimator 110; after passing through the third wave plate component 108, the polarization directions of the main sub-beams are changed to be orthogonal to each other, and the polarization directions of the weak sub-beams are also changed to be orthogonal to each other; after passing through the third birefringent crystal 109, the sub-beams with orthogonal polarization directions of the two main sub-beams are recombined and enter the first output port P2, and the sub-beams with orthogonal polarization directions of the two weak sub-beams are recombined and enter the second output port P3.

[0043] Please continue reading Figure 2 , Figure 3 as well as Figure 5 When the magneto-optical switch is in the P1->P3 optical path (switching by controlling the magnetic field direction in the opposite direction): when P1 to P3 is connected, the polarization direction of the light beam after passing through each optical element is as follows: Figure 5 As shown:

[0044] The divergent light beam outputted by the optical fiber is first collimated into a parallel light beam by a single-fiber collimator 101; after the parallel light beam passes through the first birefringent crystal 102, the parallel light beam is decomposed into two main sub-beams with orthogonal polarization directions; after passing through the first wave plate assembly 103, the polarization directions of the two main sub-beams are changed to be parallel to each other; after passing through the Faraday rotator crystal 104, the polarization directions of the two main sub-beams are rotated by 45°. When the magneto-optical switch is in the P1->P3 optical path channel, the polarization directions of the two main sub-beams are transmitted along the optical path because the direction of the magnetic field is in the opposite direction of the optical path transmission. When viewed from the direction of the light source, the two main sub-beams are rotated 45° clockwise. With respect to the second birefringent crystal 105, at this time, both the main sub-beams are extraordinary light. Similarly, due to the correlation between the extinction ratio and the wavelength of the Faraday rotatory crystal 104, not 100% of the energy is concentrated in the extraordinary light state (main sub-beam), and some very weak light energy is concentrated in the ordinary light state (i.e., two weak sub-beams are generated); after passing through the second birefringent crystal 105, both the main sub-beams are extraordinary light, and the light is deflected along the optical axis; while both the weak sub-beams are ordinary light, and the light is not deflected. Figure 5The red font polarization mark in the figure; after passing through the second wave plate component 106, the polarization directions of the two main sub-beams are rotated 135° counterclockwise when viewed along the optical path transmission direction, and the polarization directions of the two weak sub-beams are rotated 45° counterclockwise when viewed along the optical path transmission direction; after passing through the roof prism 107, the emission angle of the light beam changes to match the light emission angle of the dual-fiber collimator 110; after passing through the third wave plate component 108, the polarization directions of the two main sub-beams are changed to be orthogonal to each other, and the polarization directions of the two weak sub-beams are also changed to be orthogonal to each other; after passing through the third birefringent crystal 109, the sub-beams with orthogonal polarization directions of the two main sub-beams are recombined and enter the second output port P3, and the sub-beams with orthogonal polarization directions of the two weak sub-beams are recombined and enter the first output port P2.

[0045] 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 the strong light and the weak light into different channels (the magneto-optical switches currently on the market only couple the strong light channel, not the weak light channel). 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.

[0046] The present application realizes lossless switching of the magneto-optical switch, and changes the polarization direction of the light beam by cleverly combining multiple half-wave plate components to ensure that all light beams can be accurately converged to the output end after passing through the third birefringent crystal 109. 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 process, whether at the moment of switching or after the switching is completed.

[0047] 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 magneto-optical switch lossless switching structure, comprising a single-fiber collimator, characterized in that: The magneto-optical switch lossless switching structure further comprises a first birefringent crystal, a first wave plate assembly, a Faraday rotator crystal, a second birefringent crystal, a second wave plate assembly, a third wave plate assembly and a third birefringent crystal which are sequentially arranged; the single-fiber collimator is located on a side of the first birefringent crystal away from the first wave plate assembly; the magneto-optical switch lossless switching structure is provided with an input end, a first output end and a second output end; the input end is located on one side of the single-fiber collimator; the first output end and the second output end are located on one side of the third birefringent crystal; The parallel light beam emitted by the single-fiber collimator is decomposed into two main sub-beams with orthogonal polarization directions by the first birefringent crystal, and the polarization directions of the two main sub-beams are changed to be parallel to each other after passing through the first wave plate assembly; When the optical path from the input end to the first output end is working, the polarization directions of the two main sub-beams with mutually parallel polarization directions rotate counterclockwise after passing through the Faraday rotator crystal and generate two weak sub-beams, the two main sub-beams do not deviate when passing through the second birefringent crystal, the two weak sub-beams deviate when passing through the second birefringent crystal, the two main sub-beams rotate counterclockwise when passing through the upper area of ​​the second wave plate component, the two weak sub-beams rotate counterclockwise when passing through the lower area of ​​the second wave plate component, the polarization directions of the two main sub-beams and the two weak sub-beams are changed to be orthogonal to each other when passing through the third wave plate component, the two main sub-beams combine to enter the first output end when passing through the third birefringent crystal, and the two weak sub-beams combine to enter the second output end; When the optical path channel from the input end to the second output end is working, the polarization directions of the two main sub-beams with mutually parallel polarization directions rotate clockwise after passing through the Faraday rotator crystal and generate two weak sub-beams, the two main sub-beams are offset after passing through the second birefringent crystal, and the two weak sub-beams are not offset after passing through the second birefringent crystal, the two main sub-beams rotate counterclockwise when passing through the lower area of ​​the second wave plate component, and the two weak sub-beams rotate counterclockwise when passing through the upper area of ​​the second wave plate component, and the polarization directions of the two main sub-beams and the two weak sub-beams are changed to be orthogonal to each other when passing through the third wave plate component, and the two main sub-beams and the two weak sub-beams are combined to enter the second output end when passing through the third birefringent crystal, and the two weak sub-beams are combined to enter the first output end.

2. The magneto-optical switch lossless switching structure according to claim 1, characterized in that: The first wave plate assembly includes two half-wave plates, which are arranged on the left and right, and have different optical axes.

3. The magneto-optical switch lossless switching structure according to claim 2, characterized in that: The optical axes of the two wave plates are placed at an angle of 45° or 135° to each other.

4. The magneto-optical switch lossless switching structure according to claim 1, characterized in that: The second wave plate assembly includes two half-wave plates, which are arranged one above the other and have different optical axes.

5. The magneto-optical switch lossless switching structure according to claim 4, characterized in that: The optical axes of the two wave plates are placed at an angle of 45° or 135° to each other.

6. The magneto-optical switch lossless switching structure according to claim 1, characterized in that: When the optical path channel from the input end to the first output end is working, the two main sub-beams are ordinary light when passing through the Faraday rotator crystal, and the two weak sub-beams generated are extraordinary light; when the optical path channel from the input end to the second output end is working, the two main sub-beams are extraordinary light when passing through the Faraday rotator crystal, and the two weak sub-beams generated are ordinary light.

7. The magneto-optical switch lossless switching structure according to claim 1, characterized in that: The Faraday rotator crystal rotates the polarization direction by an angle of 45°.

8. The magneto-optical switch lossless switching structure according to claim 1, characterized in that: The second wave plate assembly rotates the polarization directions of the main sub-beam and the weak sub-beam at different angles.

9. The magneto-optical switch lossless switching structure according to claim 8, characterized in that: When the optical path channel from the input end to the first output end is working, the polarization directions of the two main sub-beams are rotated 45° counterclockwise when viewed along the optical path transmission direction, and the polarization directions of the two weak sub-beams are rotated 135° counterclockwise when viewed along the optical path transmission direction; when the optical path channel from the input end to the second output end is working, the polarization directions of the two main sub-beams are rotated 135° counterclockwise when viewed along the optical path transmission direction, and the polarization directions of the two weak sub-beams are rotated 45° counterclockwise when viewed along the optical path transmission direction.

10. The magneto-optical switch lossless switching structure according to claim 1, characterized in that: The magneto-optical switch lossless switching structure also includes a roof prism and a dual-fiber output collimator. The roof prism is located between the second wave plate component and the third wave plate component. The dual-fiber output collimator is located between the third birefringent crystal and the first output end and the second output end.

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