Lossless optical switch based on voltage driving and switching method

Abstract

The invention discloses a lossless optical switch based on voltage driving and a switching method, and belongs to the field of optical communication. Comprising a first birefringent crystal, a first half-wave plate assembly, a first Faraday optical rotation crystal, a second birefringent crystal, a second Faraday optical rotation crystal, a third Faraday optical rotation crystal, a second half-wave plate assembly and a third birefringent crystal, the second Faraday optical rotation crystal and the third Faraday optical rotation crystal are arranged in a staggered mode in the vertical direction, the three Faraday optical rotation crystals are each provided with a coil for changing the direction of a magnetic field, voltage is applied to the three Faraday optical rotation crystals to change the direction of the magnetic field to achieve switching of a main optical path, and a weak optical path is kept in a light combination state during switching. The loss of energy in the conversion process is reduced; and after the main optical path is switched, a non-working (weak) optical path can be quickly blocked, so that the directivity characteristic of the optical switch is enhanced, and the common optical crosstalk problem in a lossless magneto-optical switch is avoided.

Description

Technical Field

[0001] The present invention relates to the field of optical communication, and in particular to a lossless optical switch driven by voltage and a corresponding switching method. Background Art

[0002] In the field of optical fiber communication, as an important component in passive devices, optical switches are widely used for selective switching operations on optical signals in optical fiber communication networks. Magneto-optical switches are optical switches that utilize 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 externally applied magnetic field, thereby achieving the purpose of switching the optical path. Compared with traditional optical switches, magneto-optical switches have advantages such as fast switching speed, no moving parts, and high stability, and have received more and more attention and research.

[0003] When a magneto-optical switch is operating, its main energy flow transmits along the connected path - which we call the main optical path, while the other path, namely the weak optical path, is not completely lightless. For the magneto-optical switches currently on the market, during the switchover process, optical energy transfers from the main optical path to the weak optical path. Since the weak optical path is essentially in a blocked state, it is difficult to keep the total optical energy at each port constant during the switchover. In addition, existing lossless switching magneto-optical switches also face the problem of poor directivity, specifically manifested as crosstalk between optical signals, which is not conducive to the precise selective switching operation of optical signals by the optical transmission system. These deficiencies directly threaten the stability of the optical transmission system, and may lead to a decline in signal quality and fluctuations in system performance. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, one of the purposes of the present invention is to provide a lossless optical switch in which the sum of the optical energies in each port remains constant during switching and has good directivity after switching.

[0005] In order to overcome the deficiencies of the prior art, the second purpose of the present invention is to provide a switching method for a lossless optical switch in which the sum of the optical energies in each port remains constant and has good directivity after switching.

[0006] One of the purposes of the present invention is achieved by adopting the following technical solutions: A lossless optical switch based on voltage drive, comprising a first birefringent crystal, a first half-wave plate assembly, a first Faraday rotatory crystal, a second birefringent crystal, a second Faraday rotatory crystal, a third Faraday rotatory crystal, a second half-wave plate assembly and a third birefringent crystal arranged in sequence, wherein the second Faraday rotatory crystal and the third Faraday rotatory crystal are staggered in the vertical direction, the first Faraday rotatory crystal, the second Faraday rotatory crystal and the third Faraday rotatory crystal are all provided with a coil for changing the direction of a magnetic field, the first birefringent crystal forms a first input end on a side away from the first half-wave plate assembly, and the third birefringent crystal forms a first output end and a second output end on a side away from the second half-wave plate assembly; When no driving voltage is applied to the coils corresponding to the first Faraday rotator crystal, the second Faraday rotator crystal and the third Faraday rotator crystal, the main optical path is from the first input end to the first output end and is in a working state, and the weak optical path is from the first input end to the second output end and is in a blocking state; When a driving voltage is applied to the coil corresponding to the third Faraday rotator crystal, the polarization rotation angle of the third Faraday rotator crystal changes, and the polarization rotation angles of the first Faraday rotator crystal and the second Faraday rotator crystal remain unchanged; the main optical path is from the first input end to the first output end and is in a working state; and the weak optical path is from the first input end to the second output end and is in a light combining state; When a driving voltage is applied to the coil corresponding to the first Faraday rotator crystal, the polarization rotation angle of the first Faraday rotator crystal changes, the polarization rotation angle of the third Faraday rotator crystal remains changed, the polarization rotation angle of the second Faraday rotator crystal remains unchanged, the main optical path is switched from the first input end to the first output end to the first input end to the second output end, and the weak optical path is from the first input end to the first output end and is in a combined light state; When a driving voltage is applied to the coil corresponding to the second Faraday rotator crystal, the polarization rotation angle of the second Faraday rotator crystal changes, the polarization rotation angles of the third Faraday rotator crystal and the first Faraday rotator crystal remain changed, the main optical path is from the first input end to the second output end and is in a working state, and the weak optical path is from the first input end to the first output end and is in a blocking state.

[0007] Furthermore, the third Faraday rotator crystal, the first Faraday rotator crystal and the second Faraday rotator crystal apply forward voltages in sequence to switch the working channel from the first input end to the first output end to the first input end to the second output end.

[0008] Further, when no driving voltage is applied to the coils corresponding to the first Faraday rotator crystal, the second Faraday rotator crystal, and the third Faraday rotator crystal, the polarization rotation angles of the first Faraday rotator crystal, the second Faraday rotator crystal, and the third Faraday rotator crystal are all 45° counterclockwise rotation.

[0009] Further, when a positive voltage is applied to the coils corresponding to the first Faraday rotator crystal, the second Faraday rotator crystal, and the third Faraday rotator crystal, the polarization rotation angles of the first Faraday rotator crystal, the second Faraday rotator crystal, and the third Faraday rotator crystal change from 45° counterclockwise rotation to 45° clockwise rotation.

[0010] Further, reverse voltages are sequentially applied to the second Faraday rotator crystal, the first Faraday rotator crystal, and the third Faraday rotator crystal, so that the working channel is switched from the first input end to the second output end to the first input end to the first output end.

[0011] Further, the voltage-driven lossless optical switch further includes a single-fiber collimator, and the single-fiber collimator is located between the first input end and the first birefringent crystal, and the single-fiber collimator collimates the incident light into a parallel light beam.

[0012] Further, the voltage-driven lossless optical switch further includes a roof prism and a double-fiber output collimator. The roof prism is located between the third Faraday rotator crystal and the second half-wave plate assembly. The first output end and the second output end are arranged on the double-fiber output collimator. The roof prism changes the exit angle of the light beam to match the light output angle of the double-fiber output collimator.

[0013] The second object of the present invention is achieved by the following technical solution: A switching method for any one of the above voltage-driven lossless optical switches includes the following steps: When switching from working from the first input end to the first output end to working from the first input end to the second output end, a positive voltage is applied to the third Faraday rotator crystal, the first Faraday rotator crystal, and the second Faraday rotator crystal in sequence; when in the state where no voltage is applied at all, the main optical path is from the first input end to the first output end and is in the working state, and the weak optical path is from the first input end to the second output end and is in the blocked state; when a driving voltage is applied to the coil corresponding to the third Faraday rotator crystal, the magnetic field of the third Faraday rotator crystal changes, the main optical path is from the first input end to the first output end and is in the working state, and the weak optical path is from the first input end to the second output end and is in the combined light state; when a driving voltage is applied to the coil corresponding to the first Faraday rotator crystal, the magnetic field of the first Faraday rotator crystal changes, the main optical path switches from the first input end to the first output end to the first input end to the second output end, and the weak optical path is from the first input end to the first output end and is in the combined light state; when a driving voltage is applied to the coil corresponding to the second Faraday rotator crystal, the main optical path is from the first input end to the second output end and is in the working state, and the weak optical path is from the first input end to the first output end and is in the blocked state. When switching from working from the first input end to the second output end to working from the first input end to the first output end, a reverse voltage is applied to the second Faraday rotator crystal, the first Faraday rotator crystal, and the third Faraday rotator crystal in sequence; when in the state where no voltage is applied at all, the main optical path is from the first input end to the second output end and is in the working state, and the weak optical path is from the first input end to the first output end and is in the blocked state; when a reverse voltage is applied to the second Faraday rotator crystal, the magnetic field of the second Faraday rotator crystal changes in the reverse direction, the main optical path is from the first input end to the second output end and is in the working state, and the weak optical path is from the first input end to the first output end and is in the combined light state; when a reverse voltage is applied to the first Faraday rotator crystal, the magnetic field of the first Faraday rotator crystal changes in the reverse direction, the main optical path switches from the first input end to the second output end to the first input end to the first output end, and the weak optical path is from the first input end to the second output end and is in the combined light state; when a reverse voltage is applied to the third Faraday rotator crystal, the magnetic field of the third Faraday rotator crystal changes in the reverse direction, the main optical path is from the first input end to the first output end, and the weak optical path is from the first input end to the second output end and is in the blocked state.

[0014] Further, when switching from working from the first input end to the first output end to working from the first input end to the second output end, the duration of applying the positive voltage to the third Faraday rotator crystal, the first Faraday rotator crystal, and the second Faraday rotator crystal is the same.

[0015] Furthermore, there is a delay in the time for applying the forward voltage to the third Faraday rotatable crystal, the first Faraday rotatable crystal and the second Faraday rotatable crystal.

[0016] Compared with the prior art, the voltage-driven lossless optical switch of the present invention comprises a first birefringent crystal, a first half-wave plate assembly, a first Faraday rotatory crystal, a second birefringent crystal, a second Faraday rotatory crystal, a third Faraday rotatory crystal, a second half-wave plate assembly and a third birefringent crystal, the second Faraday rotatory crystal and the third Faraday rotatory crystal are arranged in sequence, the second Faraday rotatory crystal and the third Faraday rotatory crystal are arranged staggered in the vertical direction, the first Faraday rotatory crystal, the second Faraday rotatory crystal and the third Faraday rotatory crystal are all provided with a coil for changing the direction of the magnetic field, and the first Faraday rotatory crystal, the second Faraday rotatory crystal and the third Faraday rotatory crystal are arranged staggered in the vertical direction, and ... arranged staggered The Faraday rotator crystal and the third Faraday rotator crystal apply voltage to change the direction of the magnetic field to achieve the switching of the main optical path from the first input end to the first output end to the first input end to the second output end, and the weak optical path is kept in a combined light state during the switching, ensuring that the optical switch can almost maintain energy conservation during the switching operation, effectively reducing the energy loss in the conversion process; after the main optical path is switched, the non-working (weak) optical path can be quickly blocked, significantly enhancing the directional characteristics of the optical switch, ensuring the efficient transmission and precise guidance of the optical signal, and avoiding the common optical crosstalk problem in lossless magneto-optical switches. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The structure diagram of the voltage-driven lossless optical switch of the present invention; Figure 2 for Figure 1 A side view of a voltage-driven lossless optical switch; Figure 3 for Figure 1 A top view of a voltage-driven lossless optical switch; Figure 4 This is the coil drive timing diagram when the optical path channel working from P1->P2 switches to the optical path channel working from P1->P3; Figure 5 Schematic diagram of the polarization direction of the light beam when the main light path is P1->P2 light path channel and the weak light path P1->P3 light path channel is blocked; Figure 6 Side view of the optical path where the main optical path P1->P2 optical path channel works and the weak optical path P1->P3 optical path channel is blocked; Figure 7 The main optical path P1->P2 optical path channel works, and the weak optical path P1->P3 optical path is a schematic diagram of the light beam polarization direction in the combined light state; Figure 8For the operation of the main optical path P1->P2 optical path channel, the side view of the optical path of the weak optical path P1->P3 in the combined light state; Figure 9 Schematic diagram of the beam polarization direction of the weak optical path P1->P2 in the combined light state for switching the main optical path from P1->P2 optical path to P1->P3; Figure 10 Side view of the optical path of the weak optical path P1->P2 in the combined light state for switching the main optical path from P1->P2 optical path to P1->P3; Figure 11 Schematic diagram of the beam polarization direction of the main optical path for P1->P3 optical path channel operation and the weak optical path P1->P2 in the blocked state; Figure 12 Side view of the optical path of the main optical path for P1->P3 optical path channel operation and the weak optical path P1->P2 in the blocked state; Figure 13 Schematic diagram of the energy fluctuation during the process of switching from P1->P2 to P1->P3; Figure 14 Coil drive timing diagram when switching from P1->P3 optical path channel operation to P1->P2 optical path channel operation; Figure 15 Schematic diagram of the beam polarization direction of the main optical path for P1->P3 optical path channel operation and the optical path channel of the weak optical path P1->P2 blocked; Figure 16 Side view of the optical path of the main optical path for P1->P3 optical path channel operation and the optical path channel of the weak optical path P1->P2 blocked; Figure 17 Schematic diagram of the beam polarization direction of the main optical path for P1->P3 optical path channel operation and the weak optical path P1->P2 in the combined light state; Figure 18 Side view of the optical path of the main optical path for P1->P3 optical path channel operation and the weak optical path P1->P2 in the combined light state; Figure 19 Schematic diagram of the beam polarization direction of the main optical path for switching from P1->P3 optical path to P1->P2 and the weak optical path P1->P3 in the combined light state; Figure 20 Side view of the optical path of the main optical path for switching from P1->P3 optical path to P1->P2 and the weak optical path P1->P3 in the combined light state; Figure 21 Schematic diagram of the beam polarization direction of the main optical path for P1->P2 optical path channel operation and the weak optical path P1->P3 in the blocked state; Figure 22 Side view of the optical path of the main optical path for P1->P2 optical path channel operation and the weak optical path P1->P3 in the blocked state; Figure 23 Schematic diagram of energy fluctuation during the process of switching from P1->P3 to P1->P2.

[0018] In the figure: 101, single-fiber collimator; 102, first birefringent crystal; 103, first half-wave plate assembly; 104, first Faraday rotator crystal; 105, second birefringent crystal; 106, second Faraday rotator crystal; 107, third Faraday rotator crystal; 108, roof prism; 109, second half-wave plate assembly; 110, third birefringent crystal; 111, dual-fiber output collimator. Detailed implementation manners

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] It should be noted that when a component is referred to as being "fixed to" another component, it can be directly on the other component or there may also be another intermediate component through which it is fixed. When a component is considered to be "connected to" another component, it can 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 "disposed on" another component, it can be directly disposed 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.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein 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 of the related listed items.

[0022] Please refer to Figures 1 to 3, a voltage-driven non-destructive optical switch includes a single-fiber collimator 101, a first birefringent crystal 102, a first waveplate assembly 103, a first Faraday rotator crystal 104, a second birefringent crystal 105, a second Faraday rotator crystal 106, a third Faraday rotator crystal 107, a roof prism 108, a second half-waveplate assembly 109, a third birefringent crystal 110, and a dual-fiber output collimator 111, which are arranged in sequence. A first input end (P1) is formed on the side of the single-fiber collimator 101 away from the first birefringent crystal 102, and a first output end (P2) and a second output end (P3) are formed on the dual-fiber output collimator 111.

[0023] The single-fiber collimator 101 is used to collimate the incident light at the input end into a parallel light beam.

[0024] The first birefringent crystal 102 is used to decompose the parallel light beam into two sub-beams with orthogonal polarization directions.

[0025] The first waveplate assembly 103 is used to change the polarization directions of the two sub-beams to a parallel state. Specifically, the first waveplate assembly 103 includes two half-waveplates, which are arranged left and right, and the optical axes of the two half-waveplates are different. The optical axis angles between the two waveplates are placed at 45° or 135° to each other. Preferably, in this embodiment, the optical axis of the left waveplate is +67.5°, and the optical axis of the right waveplate is -67.5°.

[0026] The first Faraday rotator crystal 104 controls the operation of different channels of the magneto-optical switch by changing the magnetic field direction by reversing the positive and negative poles of the applied voltage. The first Faraday rotator crystal 104 rotates the polarization direction of the sub-beam. The first Faraday rotator crystal 104 is correspondingly provided with a drive coil, and by applying different voltages to the coil, the magnetic field of the first Faraday rotator crystal 104 changes.

[0027] The second birefringent crystal 105 is used to shift the light ray of the extraordinary light along the optical axis direction.

[0028] The second Faraday rotator crystal 106 controls the operation of different channels of the magneto-optical switch by changing the magnetic field direction by reversing the positive and negative poles of the applied voltage. The second Faraday rotator crystal 106 is correspondingly provided with a drive coil, and by applying different voltages to the coil, the magnetic field of the second Faraday rotator crystal 106 changes. The second Faraday rotator crystal 106 is located in the upper optical path.

[0029] The third Faraday rotator crystal 107 controls the operation of different channels of the magneto-optical switch by changing the magnetic field direction by reversing the positive and negative poles of the applied voltage. A drive coil is correspondingly arranged for the third Faraday rotator crystal 107, and different voltages are applied to the coil to change the magnetic field of the third Faraday rotator crystal 107. The third Faraday rotator crystal 107 is located in the lower path above. The third Faraday rotator crystal 107 is arranged offset from the second Faraday rotator crystal 106.

[0030] The roof prism 108 is used to change the output angle of the light beam to match the output angle of the double-fiber output collimator 111.

[0031] The second half-wave plate assembly 109 includes two half-wave plates arranged left and right with different optical axes. 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 left wave plate is +67.5° and the optical axis of the right wave plate is -67.5°.

[0032] The third birefringent crystal 110 is used to recombine the two sub-beams with orthogonal polarization directions of the principal ray into one output end, and the two sub-beams with orthogonal polarization directions of the weak ray into another output end.

[0033] Please continue to refer to Figure 4 , by sequentially applying a positive voltage to the third Faraday rotator crystal 107, the first Faraday rotator crystal 104, and the second Faraday rotator crystal 106, the optical switch switches from the optical path channel of the first input end P1 -> the first output end P2 to the optical path channel of the first input end P1 -> the second output end P3. Figure 4The positive direction of the current is from the first input terminal P1 to the first output terminal P2. t1 and t2 are delay times. The third Faraday rotator crystal 107 is first applied with a positive driving voltage. After a time t1, the first Faraday rotator crystal 104 is applied with a positive driving voltage. After another time t2, the second Faraday rotator crystal 106 is applied with a positive driving voltage. Since each Faraday rotator crystal needs to be applied with a voltage of a certain pulse width, when the first Faraday rotator crystal 104 is applied with a positive driving voltage, the positive driving voltage of the third Faraday rotator crystal 107 is still applied. The durations of the voltages applied to the third Faraday rotator crystal 107, the first Faraday rotator crystal 104, and the second Faraday rotator crystal 106 are the same. By sequentially applying positive voltages to the third Faraday rotator crystal 107, the first Faraday rotator crystal 104, and the second Faraday rotator crystal 106, the optical switch switches from the P1->P2 optical path channel working state to the P1->P3 optical path channel working state, which can be divided into the following four steps: ① The magneto-optical switch works in the P1->P2 optical path channel, the P1->P3 optical path channel is blocked, and the magneto-optical switch has high directivity; ② The magneto-optical switch maintains the P1->P2 optical path channel working state, and the P1->P3 optical path channel has the ability to combine light; ③ The magneto-optical switch switches to the P1->P3 optical path channel working state, and the P1->P2 optical path channel has the ability to combine light; ④ The magneto-optical switch maintains the P1->P3 optical path channel working state, the P1->P2 optical path channel is blocked, and the magneto-optical switch has high directivity again.

[0034] Please refer to Figure 5 and Figure 6 , in step 1, when the third Faraday rotator crystal 107, the first Faraday rotator crystal 104, and the second Faraday rotator crystal 106 have not been applied with voltages, the polarization rotation angles of the third Faraday rotator crystal 107, the first Faraday rotator crystal 104, and the second Faraday rotator crystal 106 are all rotated counterclockwise by 45°. The magneto-optical switch works in the P1->P2 optical path channel, and the P1->P3 optical path channel is blocked. The specific optical path is as follows: (1) The divergent light beam output from the optical fiber is first collimated into a parallel light beam by the single-fiber collimator 101; (2) The parallel light beam passes through the first birefringent crystal 102, and the parallel light beam is decomposed into two orthogonally polarized ordinary light o and extraordinary light e; (3) After passing through the first half-wave plate assembly 103, the polarization direction of the o light is rotated counterclockwise by 45° along the light transmission direction, and the polarization direction of the e light is rotated counterclockwise by 135° along the light transmission direction. At this time, the polarization directions of the two sub-light beams are changed to a parallel state; After passing through the first Faraday rotator crystal 104, the polarization directions of the two sub-beams are rotated counterclockwise by 45° along the optical transmission direction. At this time, both sub-beams are e-rays. Due to the extinction ratio relationship between the Faraday rotator crystal and the wave plate, not all 100% of the energy is concentrated in the e-ray state (black main optical path), and there is still some very weak optical energy concentrated in the o-ray state (red weak optical path); (5) After passing through the second birefringent crystal 105, relative to the second birefringent crystal 105, the two sub-beams on the main optical path are both ordinary rays o-rays. Therefore, the two sub-beams do not deflect when passing through the second birefringent crystal 105 and continue to be transmitted along the upper optical path. Relative to the second birefringent crystal 105, the two sub-beams on the weak optical path are both extraordinary rays e-rays. Therefore, the light rays are offset along the optical axis direction and are transmitted along the lower optical path; (6) The second Faraday rotator crystal 106 is located on the upper optical path. Therefore, only the sub-beam on the main optical path passes through. At this time, the sub-beam on the main optical path is rotated counterclockwise by 45° along the optical transmission direction; (7) The third Faraday rotator crystal 107 is located on the lower optical path. Therefore, only the sub-beam on the weak optical path passes through. At this time, the polarization direction of the sub-beam on the weak optical path is rotated counterclockwise by 45° along the optical transmission direction; (8) After passing through the roof prism 108, the exit angle of the light beam is changed to match the light output angle of the double-fiber output collimator 111; (9) After passing through the second half-wave plate assembly 109, along the optical transmission direction, the sub-beam on the left side of the main optical path is rotated counterclockwise by 45° along the optical transmission direction and is an o-ray. The sub-beam on the right side of the main optical path is rotated counterclockwise by 135° along the optical transmission direction and is an e-ray. The sub-beam on the left side of the weak optical path is rotated clockwise by 135° along the optical transmission direction and is an e-ray. The sub-beam on the right side of the weak optical path is rotated clockwise by 45° along the optical transmission direction and is an o-ray; (10) After passing through the third birefringent crystal 110, the two sub-beams with orthogonal polarization directions on the main optical path are recombined and enter the first output end (P2 port). The two sub-beams on the weak optical path cannot be recombined, and the light rays cannot enter the second output end (P3 port).

[0035] At this time, the optical path channel of the weak optical path P1->P3 is blocked, and at this time, the magneto-optical switch has the performance of high directivity.

[0036] Please refer to Figure 7 and Figure 8, in step 2, when a positive voltage is applied to the third Faraday rotator crystal 107, the polarization rotation angle of the third Faraday rotator crystal 107 changes from rotating 45° counterclockwise to rotating 45° clockwise. The polarization rotation angles of the other two Faraday rotator crystals (the first Faraday rotator crystal 104 and the second Faraday rotator crystal 106) remain at rotating 45° counterclockwise. At this time, the magneto-optical switch still operates in the P1->P2 optical path channel, and the P1->P3 optical path channel has the ability to combine light.

[0037] The specific optical path is as follows: (1) The divergent light beam output from the optical fiber is first collimated into a parallel light beam by the single-fiber collimator 101; (2) The parallel light beam passes through the first birefringent crystal 102, and the parallel light beam is decomposed into two orthogonally polarized ordinary light o and extraordinary light e; (3) After passing through the first half-wave plate assembly 103, the polarization direction of the o light rotates 45° counterclockwise along the light transmission direction, and the polarization direction of the e light rotates 135° counterclockwise along the light transmission direction. At this time, the polarization directions of the two sub-light beams are changed to a parallel state; (4) After passing through the first Faraday rotator crystal 104, the polarization directions of the two sub-light beams rotate 45° counterclockwise along the light transmission direction. At this time, both sub-light beams are e light. Due to the extinction ratio relationship between the Faraday rotator crystal and the wave plate, not all the energy is concentrated in the e light state (the black main optical path), and there is also some very weak light energy concentrated in the o light state (the red weak optical path); (5) After passing through the second birefringent crystal 105, relative to the second birefringent crystal 105, both sub-light beams on the main optical path are ordinary light o, so the two sub-light beams do not deflect when passing through the second birefringent crystal 105 and continue to be transmitted along the upper optical path. Relative to the second birefringent crystal 105, both sub-light beams on the weak optical path are extraordinary light e, so the light rays are offset along the optical axis direction and are transmitted along the lower optical path; (6) The second Faraday rotator crystal 106 is located on the upper optical path, so only the sub-light beam on the main optical path passes through. At this time, the sub-light beam on the main optical path rotates 45° counterclockwise along the light transmission direction; (7) The third Faraday rotator crystal 107 is located on the lower optical path, so only the sub-light beam on the weak optical path passes through. At this time, the polarization direction of the sub-light beam on the weak optical path rotates 45° clockwise along the light transmission direction; (8) After passing through the roof prism 108, the exit angle of the light beam changes to match the light output angle of the double-fiber output collimator 111; (9) After passing through the second half-wave plate assembly 109, along the optical transmission direction, the sub-beam located on the left side of the main optical path and the weak optical path rotates counterclockwise by 45° along the optical transmission direction and becomes the o-ray. The sub-beam located on the right side of the main optical path and the weak optical path rotates counterclockwise by 135° along the optical transmission direction and becomes the e-ray; (10) After passing through the third birefringent crystal 110, the two sub-beams with orthogonal polarization directions on the main optical path are recombined and enter the first output port (P2 port), and the two sub-beams with orthogonal polarization directions on the weak optical path are also recombined and enter the second output port (P3 port).

[0038] The above steps change the optical path channel of the weak optical path P1->P3 from the blocked state to the recombined state. The energy on the weak optical path depends on the extinction ratio of the Faraday rotator crystal and accounts for a negligible proportion in the total energy. Therefore, the energy fluctuation generated by this step can be ignored.

[0039] Please refer to Figure 9 and Figure 10 , in step three, when a positive voltage is applied to the first Faraday rotator crystal 104, at this time, the polarization rotation angle of the first Faraday rotator crystal 104 changes from rotating counterclockwise by 45° to rotating clockwise by 45°. The polarization rotation angle of the second Faraday rotator crystal 106 remains rotating counterclockwise by 45°, and the polarization rotation angle of the third Faraday rotator crystal 107 remains rotating clockwise by 45°. At this time, the magneto-optical switch changes from operating in the P1->P2 optical path channel to operating in the P1->P3 optical path channel.

[0040] The specific optical path is as follows: (1) The divergent light beam output from the optical fiber is first collimated into a parallel light beam by the single-fiber collimator 101; (2) The parallel light beam passes through the first birefringent crystal 102, and the parallel light beam is decomposed into two ordinary rays o-ray and extraordinary ray e-ray with orthogonal polarization directions; (3) After passing through the first half-wave plate assembly 103, the polarization direction of the o-ray rotates counterclockwise by 45° along the optical transmission direction, and the polarization direction of the e-ray rotates counterclockwise by 135° along the optical transmission direction. At this time, the polarization directions of the two sub-beams change to a parallel state; (4) After passing through the first Faraday rotator crystal 104, the polarization directions of the two sub-beams rotate clockwise by 45° along the optical transmission direction. At this time, both sub-beams are o-rays. Due to the extinction ratio relationship between the Faraday rotator crystal and the wave plate, not all 100% of the energy is concentrated in the o-ray state, and there is still some very weak light energy concentrated in the e-ray state; (5) After passing through the second birefringent crystal 105, with respect to the second birefringent crystal 105, both sub-beams on the main optical path are extraordinary light e-light. Therefore, the two sub-beams are deflected along the optical axis direction when passing through the second birefringent crystal 105 and are transmitted along the lower optical path. With respect to the second birefringent crystal 105, both sub-beams on the weak optical path are ordinary light o-light. Therefore, the light rays are not deflected and continue to be transmitted along the upper optical path; (6) The second Faraday rotator crystal 106 is located on the upper optical path. Therefore, only the sub-beams on the weak optical path pass through. At this time, the sub-beams on the weak optical path are rotated counterclockwise by 45° along the light transmission direction; (7) The third Faraday rotator crystal 107 is located on the lower optical path. Therefore, only the sub-beams on the main optical path pass through. At this time, the polarization direction of the sub-beams on the main optical path is rotated clockwise by 45° along the light transmission direction; (8) After passing through the roof prism 108, the exit angle of the light beam is changed to match the light output angle of the dual-fiber output collimator 111; (9) After passing through the second half-wave plate assembly 109, along the light transmission direction, the sub-beams on the left side of the main optical path and the weak optical path are rotated counterclockwise by 45° along the light transmission direction and are o-light. The sub-beams on the right side of the main optical path and the weak optical path are rotated counterclockwise by 135° along the light transmission direction and are e-light; (10) After passing through the third birefringent crystal 110, the two sub-beams with orthogonal polarization directions on the main optical path are recombined into light and enter the second output end (P3 port), and the two sub-beams with orthogonal polarization directions on the weak optical path are also recombined into light and enter the first output end (P2 port).

[0041] The above steps change the operation of the P1->P2 optical path channel to the P1->P3 optical path channel. During the switchover process, since the P1->P2 channel and the P1->P3 channel always remain in a combined light state, there will be no energy loss.

[0042] Please continue to refer to Figure 11 and Figure 12 , in step four, when a positive voltage is applied to the second Faraday rotator crystal 106, at this time, the polarization rotation angle of the second Faraday rotator crystal 106 changes from counterclockwise rotation of 45° to clockwise rotation of 45°. The polarization rotation angles of the other two Faraday rotator crystals (the first Faraday rotator crystal 104 and the third Faraday rotator crystal 107) remain clockwise rotation of 45°. At this time, the magneto-optical switch is operating in the P1->P3 optical path channel.

[0043] The specific optical path is as follows: (1) The divergent light beam output from the optical fiber is first collimated into a parallel light beam by the single-fiber collimator 101; (2) The parallel light beam passes through the first birefringent crystal 102, and the parallel light beam is decomposed into two orthogonally polarized ordinary light o and extraordinary light e; (3) After passing through the first half-wave plate assembly 103, the polarization direction of the o light rotates counterclockwise by 45° along the light transmission direction, and the polarization direction of the e light rotates counterclockwise by 135° along the light transmission direction. At this time, the polarization directions of the two sub-light beams are changed to a parallel state; (4) After passing through the first Faraday rotator crystal 104, the polarization directions of the two sub-light beams rotate clockwise by 45° along the light transmission direction. At this time, both sub-light beams are o light. Due to the extinction ratio relationship between the Faraday rotator crystal and the wave plate, not 100% of the energy is concentrated in the o light state, and there is also some very weak light energy concentrated in the e light state; (5) After passing through the second birefringent crystal 105, relative to the second birefringent crystal 105, both sub-light beams on the main optical path are extraordinary light e. Therefore, the two sub-light beams pass through the second birefringent crystal 105 and are deflected along the optical axis direction and transmitted along the lower optical path. Relative to the second birefringent crystal 105, both sub-light beams on the weak optical path are ordinary light o. Therefore, the light rays are not deflected and continue to be transmitted along the upper optical path; (6) The second Faraday rotator crystal 106 is located on the upper optical path. Therefore, only the sub-light beam on the weak optical path passes through. At this time, the sub-light beam on the weak optical path rotates clockwise by 45° along the light transmission direction; (7) The third Faraday rotator crystal 107 is located on the lower optical path. Therefore, only the sub-light beam on the main optical path passes through. At this time, the polarization direction of the sub-light beam on the main optical path rotates clockwise by 45° along the light transmission direction; (8) After passing through the roof prism 108, the exit angle of the light beam is changed to match the exit angle of the double-fiber output collimator 111; (9) After passing through the second half-wave plate assembly 109, along the light transmission direction, the sub-light beam on the left side of the main optical path rotates counterclockwise by 45° along the light transmission direction and is o light. The sub-light beam on the right side of the main optical path rotates counterclockwise by 135° along the light transmission direction and is e light. The sub-light beam on the left side of the weak optical path rotates clockwise by 135° along the light transmission direction and is e light. The sub-light beam on the right side of the weak optical path rotates clockwise by 45° along the light transmission direction and is o light; (10) After passing through the third birefringent crystal 110, the two orthogonally polarized sub-light beams on the main optical path are recombined and enter the second output end (P3 port), and the two sub-light beams on the weak optical path cannot be recombined, and the light rays cannot enter the first output end (P2 port).

[0044] The above steps change the optical path channel of the weak optical path P1->P2 from the combined light state to the blocked state, and the magneto-optical switch once again has the function of high directivity. Since the energy on the weak optical path accounts for an extremely small proportion of the total energy, the energy fluctuation generated by the above steps can be ignored. At this time, the magneto-optical switch completes the working switch from the P1->P2 optical path channel to the P1->P3 optical path channel, as Figure 13 shown. Almost no energy fluctuation is generated during the switch process, and at the same time, the high directivity of the magneto-optical switch before and after the switch is ensured.

[0045] Please continue to refer to Figure 14 , by sequentially applying reverse voltages to the second Faraday rotator crystal 106, the first Faraday rotator crystal 104, and the third Faraday rotator crystal 107, the optical switch switches from the working state of the P1->P3 optical path channel to the working state of the P1->P2 optical path channel. Figure 14 In

[0046] , t3 and t4 are delay times. The second Faraday rotator crystal 106 is first applied with a forward driving voltage. After a time t3, the first Faraday rotator crystal 104 is then applied with a reverse driving voltage. After another time t4, the third Faraday rotator crystal 107 is applied with a reverse driving voltage. Since each Faraday rotator crystal needs to be applied with a voltage of a certain pulse width, when the first Faraday rotator crystal 104 is applied with a reverse driving voltage, the reverse driving voltage of the second Faraday rotator crystal 106 is still applied. The application durations of the voltages to the second Faraday rotator crystal 106, the first Faraday rotator crystal 104, and the third Faraday rotator crystal 107 are the same.

[0047] Please refer to Figure 15 and Figure 16, in Step 1, when no voltage is applied to the second Faraday rotator crystal 106, the first Faraday rotator crystal 104, and the third Faraday rotator crystal 107, the polarization rotation angles of the second Faraday rotator crystal 106, the first Faraday rotator crystal 104, and the third Faraday rotator crystal 107 are all 45° clockwise rotation. At this time, the magneto-optical switch operates in the P1->P3 optical path channel, and the P1->P2 optical path channel is blocked. At this time, the magneto-optical switch has the performance of high directivity.

[0048] The specific optical path is as follows: (1) The divergent light beam output from the optical fiber is first collimated into a parallel light beam by the single-fiber collimator 101; (2) The parallel light beam passes through the first birefringent crystal 102, and the parallel light beam is decomposed into two orthogonally polarized ordinary light o and extraordinary light e; (3) After passing through the first half-wave plate assembly 103, the polarization direction of the o light rotates 45° counterclockwise along the light transmission direction, and the polarization direction of the e light rotates 135° counterclockwise along the light transmission direction. At this time, the polarization directions of the two sub-light beams are changed to a parallel state; (4) After passing through the first Faraday rotator crystal 104, the polarization directions of the two sub-light beams rotate 45° clockwise along the light transmission direction. At this time, both sub-light beams are o light. Due to the extinction ratio relationship between the Faraday rotator crystal and the wave plate, not all the energy is concentrated in the o light state, and there is still some very weak light energy concentrated in the e light state; (5) After passing through the second birefringent crystal 105, with respect to the second birefringent crystal 105, the two sub-light beams on the main optical path are both extraordinary light e, so the two sub-light beams are deflected along the optical axis direction through the second birefringent crystal 105 and transmitted along the lower optical path. With respect to the second birefringent crystal 105, the two sub-light beams on the weak optical path are both ordinary light o, so the light will not be deflected and continues to be transmitted along the upper optical path; (6) The second Faraday rotator crystal 106 is located on the upper optical path, so only the sub-light beam on the weak optical path passes through. At this time, the sub-light beam on the weak optical path rotates 45° clockwise along the light transmission direction; (7) The third Faraday rotator crystal 107 is located on the lower optical path, so only the sub-light beam on the main optical path passes through. At this time, the polarization direction of the sub-light beam on the main optical path rotates 45° clockwise along the light transmission direction; (8) After passing through the roof prism 108, the exit angle of the light beam is changed to match the light output angle of the double-fiber output collimator 111; (9) After passing through the second half-wave plate assembly 109, along the optical transmission direction, the sub-beam on the left side of the main optical path rotates counterclockwise by 45° along the optical transmission direction and becomes the o-light. The sub-beam on the right side of the main optical path rotates counterclockwise by 135° along the optical transmission direction and becomes the e-light. The sub-beam on the left side of the weak optical path rotates clockwise by 135° along the optical transmission direction and becomes the e-light. The sub-beam on the right side of the weak optical path rotates clockwise by 45° along the optical transmission direction and becomes the o-light; (10) After passing through the third birefringent crystal 110, the two sub-beams with orthogonal polarization directions on the main optical path recombine and enter the second output port (P3 port). The two sub-beams on the weak optical path cannot recombine, and the light cannot enter the first output port (P2 port).

[0049] At this time, the optical path channel of the weak optical path from P1 to P2 is blocked, and the magneto-optical switch has the performance of high directivity.

[0050] Please refer to Figure 17 and Figure 18 , by applying a reverse voltage to the second Faraday rotator crystal 106, the polarization rotation angle of the second Faraday rotator crystal 106 changes from clockwise rotation by 45° to counterclockwise rotation by 45°. The polarization rotation angles of the other two Faraday rotator crystals (the first Faraday rotator crystal 104 and the third Faraday rotator crystal 107) remain at clockwise rotation by 45°. At this time, the magneto-optical switch still operates in the P1->P3 optical path channel, and the P1->P2 optical path changes to a combined light state.

[0051] The specific optical path is as follows: (1) The divergent light beam output from the optical fiber is first collimated into a parallel light beam by the single-fiber collimator 101; (2) The parallel light beam passes through the first birefringent crystal 102, and the parallel light beam is decomposed into two orthogonally polarized ordinary light o-light and extraordinary light e-light; (3) After passing through the first half-wave plate assembly 103, the polarization direction of the o-light rotates counterclockwise by 45° along the optical transmission direction, and the polarization direction of the e-light rotates counterclockwise by 135° along the optical transmission direction. At this time, the polarization directions of the two sub-beams change to a parallel state; (4) After passing through the first Faraday rotator crystal 104, the polarization directions of the two sub-beams rotate clockwise by 45° along the optical transmission direction. At this time, both sub-beams are o-light. Due to the extinction ratio relationship between the Faraday rotator crystal and the wave plate, not all 100% of the energy is concentrated in the o-light state, and there is still some very weak light energy concentrated in the e-light state; (5) After passing through the second birefringent crystal 105, with respect to the second birefringent crystal 105, both sub-beams on the main optical path are extraordinary light e-rays. Therefore, the two sub-beams are deflected along the optical axis direction when passing through the second birefringent crystal 105 and are transmitted along the lower optical path. With respect to the second birefringent crystal 105, both sub-beams on the weak optical path are ordinary light o-rays. Therefore, the light rays will not be deflected and continue to be transmitted along the upper optical path; (6) The second Faraday rotator crystal 106 is located on the upper optical path. Therefore, only the sub-beams on the weak optical path pass through. At this time, the sub-beams on the weak optical path are rotated counterclockwise by 45° along the light transmission direction; (7) The third Faraday rotator crystal 107 is located on the lower optical path. Therefore, only the sub-beams on the main optical path pass through. At this time, the polarization direction of the sub-beams on the main optical path is rotated clockwise by 45° along the light transmission direction; (8) After passing through the roof prism 108, the exit angle of the light beam is changed to match the light output angle of the dual-fiber output collimator 111; (9) After passing through the second half-wave plate assembly 109, along the light transmission direction, the sub-beams on the left side of the main optical path and the weak optical path are rotated counterclockwise by 45° along the light transmission direction and are o-rays. The sub-beams on the right side of the main optical path and the weak optical path are rotated counterclockwise by 135° along the light transmission direction and are e-rays; (10) After passing through the third birefringent crystal 110, the two sub-beams with orthogonal polarization directions on the main optical path are recombined into light and enter the second output end (P3 port), and the two sub-beams with orthogonal polarization directions on the weak optical path are also recombined into light and enter the first output end (P2 port).

[0052] Step 2 changes the weak optical path P1->P2 optical path channel from the blocked state to the light recombination state. The energy on the weak optical path depends on the extinction ratio of the Faraday rotator crystal and accounts for a negligible proportion in the total energy. Therefore, the energy fluctuation generated in this step can be ignored.

[0053] Please refer to Figure 19 and Figure 20 , by applying a reverse voltage to the first Faraday rotator crystal 104, the polarization rotation angle of the first Faraday rotator crystal 104 is changed from clockwise rotation by 45° to counterclockwise rotation by 45°. The polarization rotation angle of the second Faraday rotator crystal 106 remains counterclockwise rotation by 45°, and the polarization rotation angle of the third Faraday rotator crystal 107 remains clockwise rotation by 45°. At this time, the magneto-optical switch changes from operating in the P1->P3 optical path channel to operating in the P1->P2 optical path channel.

[0054] The specific optical path is: (1) The divergent light beam output from the optical fiber is first collimated into a parallel light beam by the single-fiber collimator 101; (2) The parallel light beam passes through the first birefringent crystal 102, and the parallel light beam is decomposed into two orthogonally polarized ordinary light o and extraordinary light e; (3) After passing through the first half-wave plate assembly 103, the polarization direction of the o light rotates counterclockwise by 45° along the light transmission direction, and the polarization direction of the e light rotates counterclockwise by 135° along the light transmission direction. At this time, the polarization directions of the two sub-light beams are changed to a parallel state; (4) After passing through the first Faraday rotator crystal 104, the polarization directions of the two sub-light beams rotate counterclockwise by 45° along the light transmission direction. At this time, both sub-light beams are e light. Due to the extinction ratio relationship between the Faraday rotator crystal and the wave plate, not all 100% of the energy is concentrated in the e light state, and there is also some very weak light energy concentrated in the o light state; (5) After passing through the second birefringent crystal 105, with respect to the second birefringent crystal 105, both sub-light beams on the main optical path are ordinary light o, so the two sub-light beams do not deflect when passing through the second birefringent crystal 105 and continue to be transmitted along the upper optical path. With respect to the second birefringent crystal 105, both sub-light beams on the weak optical path are extraordinary light e, so the light deflects along the optical axis direction and is transmitted along the lower optical path; (6) The second Faraday rotator crystal 106 is located on the upper optical path, so only the sub-light beam on the main optical path passes through. At this time, the sub-light beam on the main optical path rotates counterclockwise by 45° along the light transmission direction; (7) The third Faraday rotator crystal 107 is located on the lower optical path, so only the sub-light beam on the weak optical path passes through. At this time, the polarization direction of the sub-light beam on the weak optical path rotates clockwise by 45° along the light transmission direction; (8) After passing through the roof prism 108, the exit angle of the light beam changes to match the exit angle of the double-fiber output collimator 111; (9) After passing through the second half-wave plate assembly 109, along the light transmission direction, the sub-light beam on the left side of the main optical path and the weak optical path rotates counterclockwise by 45° along the light transmission direction and is o light. The sub-light beam on the right side of the main optical path and the weak optical path rotates counterclockwise by 135° along the light transmission direction and is e light; (10) After passing through the third birefringent crystal 110, the two orthogonally polarized sub-light beams on the main optical path are recombined and enter the first output end (P2 port), and the two orthogonally polarized sub-light beams on the weak optical path are also recombined and enter the second output end (P3 port).

[0055] Step three changes the operation of the P1->P2 optical path channel to the P1->P3 optical path channel. During the switchover process, since the P1->P2 channel and the P1->P3 channel always maintain a combined light state, there will be no energy loss.

[0056] Please refer to Figure 21 AndFigure 22 , by applying a reverse voltage to the third Faraday rotator crystal 107, the polarization rotation angle of the third Faraday rotator crystal 107 changes from a 45° clockwise rotation to a 45° counterclockwise rotation. The polarization rotation angles of the other two Faraday rotator crystals (the first Faraday rotator crystal 104 and the second Faraday rotator crystal 106) remain at a 45° counterclockwise rotation. At this time, the magneto-optic switch is operating in the P1->P2 optical path channel.

[0057] The specific optical path is as follows: (1) The divergent light beam output from the optical fiber is first collimated into a parallel light beam by the single-fiber collimator 101; (2) The parallel light beam passes through the first birefringent crystal 102, and the parallel light beam is decomposed into two orthogonally polarized ordinary light o and extraordinary light e; (3) After passing through the first half-wave plate assembly 103, the polarization direction of the o light rotates 45° counterclockwise along the light transmission direction, and the polarization direction of the e light rotates 135° counterclockwise along the light transmission direction. At this time, the polarization directions of the two sub-light beams are changed to a parallel state; (4) After passing through the first Faraday rotator crystal 104, the polarization directions of the two sub-light beams rotate 45° counterclockwise along the light transmission direction. At this time, both sub-light beams are e light. Due to the extinction ratio relationship between the Faraday rotator crystal and the wave plate, not all of the energy is concentrated in the e light state, and there is also some very weak light energy concentrated in the o light state; (5) After passing through the second birefringent crystal 105, with respect to the second birefringent crystal 105, both sub-light beams on the main optical path are ordinary light o, so the two sub-light beams do not deflect when passing through the second birefringent crystal 105 and continue to be transmitted along the upper optical path. With respect to the second birefringent crystal 105, both sub-light beams on the weak optical path are extraordinary light e, so the light rays are offset along the optical axis direction and are transmitted along the lower optical path; (6) The second Faraday rotator crystal 106 is located on the upper optical path, so only the sub-light beam on the main optical path passes through. At this time, the sub-light beam on the main optical path rotates 45° counterclockwise along the light transmission direction; (7) The third Faraday rotator crystal 107 is located on the lower optical path, so only the sub-light beam on the weak optical path passes through. At this time, the polarization direction of the sub-light beam on the weak optical path rotates 45° counterclockwise along the light transmission direction; (8) After passing through the roof prism 108, the exit angle of the light beam changes to match the light output angle of the dual-fiber output collimator 111; (9) After passing through the second half-wave plate assembly 109, along the optical transmission direction, the sub-beam on the left side of the main optical path rotates counterclockwise by 45° along the optical transmission direction and becomes the o-ray. The sub-beam on the right side of the main optical path rotates counterclockwise by 135° along the optical transmission direction and becomes the e-ray. The sub-beam on the left side of the weak optical path rotates clockwise by 135° along the optical transmission direction and becomes the e-ray. The sub-beam on the right side of the weak optical path rotates clockwise by 45° along the optical transmission direction and becomes the o-ray; (10) After passing through the third birefringent crystal 110, the two sub-beams with orthogonal polarization directions on the main optical path are recombined and enter the first output end (P2 port). The two sub-beams on the weak optical path cannot be recombined, and the light cannot enter the first output end (P3 port).

[0058] Step 4 changes the optical path channel of the weak optical path P1->P3 from the combined light state to the blocked state, and the magneto-optical switch once again has the function of high directivity. Since the energy on the weak optical path accounts for an extremely small proportion of the total energy, the energy fluctuation generated in Step 4 can be ignored. At this time, the magneto-optical switch completes the working switch from the P1->P3 optical path channel to the P1->P2 optical path channel. As Figure 23 shown, almost no energy fluctuation is generated during the switch process, and at the same time, the high directivity of the magneto-optical switch before and after the switch is ensured.

[0059] It can be known from the switching process of the above magneto-optical switch that the lossless switching and high-directivity device characteristics of the magneto-optical switch can be realized through the driving delay between the three Faraday rotator crystals.

[0060] In this application, the driving coil is delayed through circuit design, thereby realizing the lossless switching and high-directivity device characteristics of the magneto-optical switch. A voltage-driven lossless optical switch in this application uses a coil driving timing strategy to precisely control the change of the external magnetic field around the Faraday magneto-optical crystal, ensuring that the magneto-optical switch can almost maintain energy conservation during the switching operation, effectively reducing the energy loss during the conversion process. After successfully completing the switching of the working optical path channel, this design can quickly block the non-working (weak) optical path. This mechanism significantly enhances the directivity characteristics of the magneto-optical switch, ensuring the efficient transmission and precise guiding of optical signals. The present invention not only greatly reduces the energy loss during the switching process, but also avoids the common optical crosstalk problem in lossless magneto-optical switches, has the ability to maintain the overall stability and signal selectivity of the optical transmission system, and helps to build a more reliable and efficient optical transmission system.

[0061] This application also discloses a switching method for the above voltage-driven lossless optical switch, including the following steps: When switching from operating with the first input terminal to the first output terminal to operating with the first input terminal to the second output terminal, a positive voltage is applied to the third Faraday rotator crystal 107, the first Faraday rotator crystal 104, and the second Faraday rotator crystal 106 in sequence; when none of them is applied, the main optical path is from the first input terminal to the first output terminal and is in the operating state, and the weak optical path is from the first input terminal to the second output terminal and is in the blocked state; when a driving voltage is applied to the coil corresponding to the third Faraday rotator crystal 107, the magnetic field of the third Faraday rotator crystal 107 changes, the main optical path is from the first input terminal to the first output terminal and is in the operating state, and the weak optical path is from the first input terminal to the second output terminal and is in the combined light state; when a driving voltage is applied to the coil corresponding to the first Faraday rotator crystal 104, the magnetic field of the first Faraday rotator crystal 104 changes, the main optical path switches from the first input terminal to the first output terminal to the first input terminal to the second output terminal, and the weak optical path is from the first input terminal to the first output terminal and is in the combined light state; when a driving voltage is applied to the coil corresponding to the second Faraday rotator crystal 106, the main optical path is from the first input terminal to the second output terminal and is in the operating state, and the weak optical path is from the first input terminal to the first output terminal and is in the blocked state; When switching from operating with the first input terminal to the second output terminal to operating with the first input terminal to the first output terminal, a reverse voltage is applied to the second Faraday rotator crystal 106, the first Faraday rotator crystal 104, and the third Faraday rotator crystal 107 in sequence; when none of them is applied, the main optical path is from the first input terminal to the second output terminal and is in the operating state, and the weak optical path is from the first input terminal to the first output terminal and is in the blocked state; when a reverse voltage is applied to the second Faraday rotator crystal 106, the magnetic field of the second Faraday rotator crystal 106 changes in the reverse direction, the main optical path is from the first input terminal to the second output terminal and is in the operating state, and the weak optical path is from the first input terminal to the first output terminal and is in the combined light state; when a reverse voltage is applied to the first Faraday rotator crystal 104, the magnetic field of the first Faraday rotator crystal 104 changes in the reverse direction, the main optical path switches from the first input terminal to the second output terminal to the first input terminal to the first output terminal, and the weak optical path is from the first input terminal to the second output terminal and is in the combined light state; when a reverse voltage is applied to the third Faraday rotator crystal 107, the magnetic field of the third Faraday rotator crystal 107 changes in the reverse direction, the main optical path is from the first input terminal to the first output terminal, and the weak optical path is from the first input terminal to the second output terminal and is in the blocked state.

[0062] When switching from operating with the first input terminal to the first output terminal to operating with the first input terminal to the second output terminal, the durations of applying the positive voltage to the third Faraday rotator crystal 107, the first Faraday rotator crystal 104, and the second Faraday rotator crystal 106 are the same. There is a delay in the time of applying the positive voltage to the third Faraday rotator crystal 107, the first Faraday rotator crystal 104, and the second Faraday rotator crystal 106.

[0063] The above embodiments merely illustrate several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made. These are all equivalent modifications and evolutions based on the substantial technology of the present invention to the above embodiments, and all of these fall within the protection scope of the present invention.

Claims

1. A voltage-driven non-destructive optical switch, characterized in that: It includes a first birefringent crystal, a first half-wave plate assembly, a first Faraday rotator crystal, a second birefringent crystal, a second Faraday rotator crystal, a third Faraday rotator crystal, a second half-wave plate assembly, and a third birefringent crystal arranged in sequence. The second Faraday rotator crystal and the third Faraday rotator crystal are arranged staggeredly in the vertical direction. Coils for changing the magnetic field direction are provided on the first Faraday rotator crystal, the second Faraday rotator crystal, and the third Faraday rotator crystal. A first input end is formed on the side of the first birefringent crystal away from the first half-wave plate assembly, and a first output end and a second output end are formed on the side of the third birefringent crystal away from the second half-wave plate assembly; When no driving voltage is applied to the coils corresponding to the first Faraday rotator crystal, the second Faraday rotator crystal, and the third Faraday rotator crystal, the main optical path is from the first input end to the first output end and is in the working state, and the weak optical path is from the first input end to the second output end and is in the blocked state; When a driving voltage is applied to the coil corresponding to the third Faraday rotator crystal, the polarization rotation angle of the third Faraday rotator crystal changes, the polarization rotation angles of the first Faraday rotator crystal and the second Faraday rotator crystal remain unchanged, the main optical path is from the first input end to the first output end and is in the working state, and the weak optical path is from the first input end to the second output end and is in the light-combining state; When a driving voltage is applied to the coil corresponding to the first Faraday rotator crystal, the polarization rotation angle of the first Faraday rotator crystal changes, the polarization rotation angle of the third Faraday rotator crystal remains in the changed state, the polarization rotation angle of the second Faraday rotator crystal remains unchanged, the main optical path switches from the first input end to the first output end to the first input end to the second output end, and the weak optical path is from the first input end to the first output end and is in the light-combining state; When a driving voltage is applied to the coil corresponding to the second Faraday rotator crystal, the polarization rotation angle of the second Faraday rotator crystal changes, the polarization rotation angles of the third Faraday rotator crystal and the first Faraday rotator crystal remain in the changed state, the main optical path is from the first input end to the second output end and is in the working state, and the weak optical path is from the first input end to the first output end and is in the blocked state.

2. The voltage-driven non-destructive optical switch according to claim 1, characterized in that: Positive voltages are applied to the third Faraday rotator crystal, the first Faraday rotator crystal, and the second Faraday rotator crystal in sequence, so that the working channel switches from the first input end to the first output end to the first input end to the second output end.

3. The voltage-driven non-destructive optical switch according to claim 1, characterized in that: When no driving voltage is applied to the coils corresponding to the first Faraday rotator crystal, the second Faraday rotator crystal, and the third Faraday rotator crystal, the polarization rotation angles of the first Faraday rotator crystal, the second Faraday rotator crystal, and the third Faraday rotator crystal are all rotated counterclockwise by 45°.

4. The voltage-driven non-destructive optical switch according to claim 3, characterized in that: When a positive voltage is applied to the coils corresponding to the first Faraday rotator crystal, the second Faraday rotator crystal, and the third Faraday rotator crystal, the polarization rotation angles of the first Faraday rotator crystal, the second Faraday rotator crystal, and the third Faraday rotator crystal change from a 45° counterclockwise rotation to a 45° clockwise rotation.

5. The voltage-driven non-destructive optical switch according to claim 1, characterized in that: A reverse voltage is applied to the second Faraday rotator crystal, the first Faraday rotator crystal, and the third Faraday rotator crystal in sequence, so that the working channel is switched from the first input end to the second output end to the first input end to the first output end.

6. The voltage-driven non-destructive optical switch according to claim 1, characterized in that: The voltage-driven lossless optical switch further includes a single-fiber collimator, which is located between the first input end and the first birefringent crystal, and the single-fiber collimator collimates the incident light into a parallel light beam.

7. The voltage-driven non-destructive optical switch according to claim 1, characterized in that: The voltage-driven lossless optical switch further includes a roof prism and a dual-fiber output collimator. The roof prism is located between the third Faraday rotator crystal and the second half-wave plate assembly. The first output end and the second output end are arranged on the dual-fiber output collimator. The roof prism changes the exit angle of the light beam to match the light output angle of the dual-fiber output collimator.

8. A voltage-driven lossless optical switch switching method according to any one of claims 1-7, characterized in that, Including the following steps: When switching from working from the first input end to the first output end to working from the first input end to the second output end, a positive voltage is applied to the third Faraday rotator crystal, the first Faraday rotator crystal, and the second Faraday rotator crystal in sequence; when in the all-unapplied state, the main optical path is from the first input end to the first output end and is in the working state, and the weak optical path is from the first input end to the second output end and is in the blocked state; when a driving voltage is applied to the coil corresponding to the third Faraday rotator crystal, the magnetic field of the third Faraday rotator crystal changes, the main optical path is from the first input end to the first output end and is in the working state, and the weak optical path is from the first input end to the second output end and is in the combined light state; when a driving voltage is applied to the coil corresponding to the first Faraday rotator crystal, the magnetic field of the first Faraday rotator crystal changes, the main optical path is switched from the first input end to the first output end to the first input end to the second output end, and the weak optical path is from the first input end to the first output end and is in the combined light state; When a driving voltage is applied to the coil corresponding to the second Faraday rotator crystal, the main optical path is from the first input end to the second output end and is in the working state, and the weak optical path is from the first input end to the first output end and is in the blocked state; When switching from working from the first input end to the second output end to working from the first input end to the first output end, a reverse voltage is applied to the second Faraday rotator crystal, the first Faraday rotator crystal, and the third Faraday rotator crystal in sequence. When in the all-unapplied state, the main optical path is from the first input end to the second output end and is in the working state, and the weak optical path is from the first input end to the first output end and is in the blocked state; when a reverse voltage is applied to the second Faraday rotator crystal, the magnetic field of the second Faraday rotator crystal changes in the reverse direction, the main optical path is from the first input end to the second output end and is in the working state, and the weak optical path is from the first input end to the first output end and is in the combined-light state; when a reverse voltage is applied to the first Faraday rotator crystal, the magnetic field of the first Faraday rotator crystal changes in the reverse direction, the main optical path switches from the first input end to the second output end to the first input end to the first output end, and the weak optical path is from the first input end to the second output end and is in the combined-light state; when a reverse voltage is applied to the third Faraday rotator crystal, the magnetic field of the third Faraday rotator crystal changes in the reverse direction, the main optical path is from the first input end to the first output end, and the weak optical path is from the first input end to the second output end and is in the blocked state.

9. The voltage-driven lossless optical switch switching method according to claim 8, characterized in that: When switching from working from the first input end to the first output end to working from the first input end to the second output end, the durations of applying the forward voltage to the third Faraday rotator crystal, the first Faraday rotator crystal, and the second Faraday rotator crystal are the same.

10. The voltage-driven lossless optical switch switching method according to claim 8, characterized in that: There is a delay in the time of applying the forward voltage to the third Faraday rotator crystal, the first Faraday rotator crystal, and the second Faraday rotator crystal.

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