An automatic feedback port switchable spatial optical circulator and a port switching method

Abstract

The application relates to an automatic feedback port switchable spatial light ring shaper and a port switching method, and belongs to the field of spatial optics, and particularly relates to a spatial light ring shaper. The application solves the technical problem that the prior art spatial light ring shaper cannot realize dynamic adjustment of ports. The spatial light ring shaper is internally provided with a first light path, a second light path, an electric control rotary displacement table A and an electric control rotary displacement table B for supporting and adjusting the included angle between the fast axis of a liquid crystal electric control retarder in the light path and an x axis, a double-channel liquid crystal driver for controlling the phase delay of the liquid crystal electric control retarder, a first port and a third port for receiving light transmitted by a broadband polarization beam splitting prism A or emitting light to the broadband polarization beam splitting prism A, a second port and a fourth port for receiving light transmitted by a broadband polarization beam splitting prism B or emitting light to the broadband polarization beam splitting prism B, and optical power meters A and B for detecting the output optical power of the second port and the fourth port.

Description

Technical Field

[0001] This invention relates to the field of space optics, and more specifically to space optical circulators. Background Technology

[0002] Common-aperture optical transceiver systems have important applications in fields such as lidar and space optical communication. Common-aperture transceiver optical antennas can significantly improve system integration and suppress the impact of coaxiality errors on system robustness, which is of great significance for the miniaturization of lidar and laser communication systems.

[0003] Currently, the optical circulators on the market are mainly fiber optic circulators. Fiber optic circulators are made by tapered coupling of fused fiber. They mainly achieve unidirectional deflection of the beam through waveguide coupling theory. Some fiber optic circulators are composed of microstructured spatial devices, but the pigtails are all single-mode fibers with NA 0.14 and core diameter of 9μm. They have extremely high requirements for the coupling of spatial light and cannot meet the problem of dynamic angle adjustment in space optical systems.

[0004] Space optical circulators primarily achieve unidirectional beam transmission through polarization isolation, with a light aperture on the order of millimeters. Compared to the micrometer-scale light aperture of optical fibers, they are easier to integrate into space optical systems.

[0005] In the existing technology, there are related patented technologies for spatial optical circulators, but they require complex assembly and adjustment processes to achieve mode matching of spatial optical polarization. For example, a four-port optical circulator described in Chinese patent document CN222014514U can switch ports but cannot achieve continuous port switching, that is, it cannot dynamically switch ports and cannot guarantee the performance consistency of a wide band, which greatly limits the application scenarios of spatial optical circulators. Summary of the Invention

[0006] This invention solves the technical problem that existing spatial optical circulators cannot achieve dynamic port adjustment.

[0007] Option 1: The automatic feedback port switchable spatial optical circulator described in this invention has the following features inside: The first optical path includes: a broadband polarizing beam splitter prism A, a Faraday rotator A, a liquid crystal electronically controlled delay unit A, and a broadband polarizing beam splitter prism B; The second optical path includes: a broadband polarizing beam splitter prism A, a Faraday rotator B, a liquid crystal electronically controlled delay unit B, and a broadband polarizing beam splitter prism B. An electrically controlled rotary displacement stage A is used to support and adjust the angle between the fast axis and the x-axis of the liquid crystal electrically controlled delay unit A; An electrically controlled rotary displacement stage B is used to support and adjust the angle between the fast axis and the x-axis of the liquid crystal electrically controlled delay device B. A dual-channel liquid crystal driver is used to control the phase delay of the liquid crystal electronically controlled delay unit A and the liquid crystal electronically controlled delay unit B respectively. First port, second port, third port, fourth port, optical power meter A and optical power meter B; The first port and the third port are used to receive light transmitted or emitted from the broadband polarization beam splitter A. The second port and the fourth port are used to receive light transmitted or emitted from the broadband polarization beam splitter B. The optical power meter A and the optical power meter B are used to detect the output optical power of the second port and the fourth port, respectively.

[0008] In a further optimized scheme, the broadband polarizing beam splitter A and the broadband polarizing beam splitter B operate at the same wavelength, covering a range of 1525~1570nm. The Faraday rotator A and the Faraday rotator B have the same operating wavelength, covering a range of 1500~1600nm.

[0009] In a further optimized scheme, the optical rotation angle between Faraday rotator A and Faraday rotator B is 45±0.5°. The fast axis of the liquid crystal electronically controlled delay unit A forms an angle of 22.5° or 67.5° with the x-axis; The fast axis of the liquid crystal electronically controlled delay unit B forms an angle of 22.5° or 67.5° with the x-axis; The liquid crystal electronically controlled delay unit A and the liquid crystal electronically controlled delay unit B respectively adjust the phase delay of the optical signals in the first optical path and the second optical path to λ / 2.

[0010] In a further optimized scheme, a plane mirror A is provided on the optical path between the broadband polarizing beam splitter A and the Faraday rotator A to adjust the direction of the optical path; A plane mirror B is disposed on the optical path between the broadband polarizing beam splitter B and the liquid crystal electronically controlled delay device B to adjust the direction of the optical path.

[0011] In a further optimized design, the reflectivity of the plane mirror A and the plane mirror B is the same, both greater than 95%.

[0012] In a further optimized design, the plane mirror A and the plane mirror B operate at the same wavelength, covering a range of 800~2000nm.

[0013] Option 2: A method for automatically switching the feedback port of a spatial optical circulator, the method comprising the following steps: When the light beam enters from the first port or the third port and enters the second port or the fourth port; A broadband polarizing beam splitter A splits an optical signal into light A and light B, which are respectively incident on the first optical path and the second optical path. Light A is incident on optical power meter B through the first optical path, and light B is incident on optical power meter A through the second optical path; The optical power outputs of optical power meter A and optical power meter B are collected in real time, and the angle between the fast axis and the x-axis of the liquid crystal electronically controlled delay unit A and the fast axis and the x-axis of the liquid crystal electronically controlled delay unit B are controlled according to the optical power. When the light beam is input from the first port to the second port, or from the third port to the fourth port, the angle between the fast axis and the x-axis of the liquid crystal electronically controlled delay unit A and the liquid crystal electronically controlled delay unit B is 67.5°. When the light beam is input from the first port to the fourth port, or from the third port to the second port, the angle between the fast axis and the x-axis of the liquid crystal electronically controlled delay unit A and the liquid crystal electronically controlled delay unit B is 22.5°. When the light beam is input from the second or fourth port to the first or third port; The broadband polarizing beam splitter B splits the optical signal into light C and light D, which are respectively incident on the first optical path and the second optical path. Control the angle between the fast axis and the x-axis of the liquid crystal electronically controlled delay unit A and the liquid crystal electronically controlled delay unit B; When the light path exits to the first port, the light C passes through the first optical path to the broadband polarization beam splitter A and is an s-light; the light D passes through the second optical path to the broadband polarization beam splitter A and is a p-light. When the light path exits to the third port, the light C passes through the first optical path to the broadband polarization beam splitter A and is p-light; the light D passes through the second optical path to the broadband polarization beam splitter A and is s-light.

[0014] Further optimize the scheme to control the power ratio of the optical power meter at the output port to that at the non-output port to be greater than 1000:1.

[0015] The beneficial effects of this invention compared to the prior art are as follows: The present invention discloses an automatic feedback port switchable spatial optical circulator equipped with a liquid crystal electronically controlled delay unit A and a liquid crystal electronically controlled delay unit B. By controlling the angle between the fast axis of liquid crystal electronically controlled delay unit A and the fast axis and x-axis of liquid crystal electronically controlled delay unit B, the arrival port can be dynamically changed, and the port can be automatically switched according to the usage requirements without secondary adjustment.

[0016] The automatic feedback port switchable spatial optical circulator described in this invention can achieve coverage of any polarization state beam in the wavelength range of 1530-1570nm through the cooperation of a broadband polarization beam splitter prism, a plane mirror, a Faraday rotator, and a liquid crystal electronically controlled delay device. Compared with the waveplate used in traditional spatial optical circulators, this invention introduces a liquid crystal electronically controlled delay device, in which the liquid crystal waveplate can dynamically compensate for the phase shift error introduced by different wavelengths, maintain the consistency of the isolation of circulators at different wavelengths, and reduce the limitation on the operating wavelength of the system.

[0017] The present invention discloses an automatic feedback port switchable spatial optical circulator equipped with an optical power generator. The optical power generator monitors the output power of the port to achieve automatic power feedback adjustment based on the change of optical power of the output port, thereby compensating for polarization errors introduced by device reflection and its own errors, suppressing stray light output from unused ports, and improving the output efficiency of the designated ports.

[0018] The spatial optical circulator with switchable automatic feedback ports described in this invention can achieve dynamic adjustment of the ports, and is small in size, applicable to a wide range of wavelengths, and suitable for more scenarios. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the internal structure of a spatial optical circulator with an automatically switchable feedback port as described in Embodiment 1. Figure 2 for Figure 1 The diagram shows the optical path of a spatial optical circulator.

[0020] Figure label: 1. Broadband polarizing beam splitter A; 2. Broadband polarizing beam splitter B; 3. Plane mirror A; 4. Plane mirror B; 5. Faraday rotator A; 6. Faraday rotator B; 7. Liquid crystal electronically controlled delay unit A; 8. Liquid crystal electronically controlled delay unit B; 9. Electronically controlled rotary stage A; 10. Electronically controlled rotary stage B; 11. Dual-channel liquid crystal driver; 12. Optical power meter A; 13. Optical power meter B; 14. Host computer; 15. Communication unit A; 16. Communication unit B; 17. Optical transceiver A; 18. Optical transceiver B; 19. Optical A; 20. Optical C; 21. Optical B; 22. Optical D; 51. First port; 52. Third port; 53. Fourth port; 54. Second port. Detailed Implementation

[0021] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] It should be noted that some of the accompanying drawings are in a very simplified form and are not to scale, and are only used to facilitate and clearly illustrate the purpose of the embodiments of the present invention.

[0026] Implementation Method 1: Refer to Figure 1 and Figure 2 This embodiment describes a spatial optical circulator with a switchable automatic feedback port, which has two internal optical paths: The first optical path includes: a broadband polarizing beam splitter prism A1, a Faraday rotator A5, a liquid crystal electronically controlled delay unit A7, and a broadband polarizing beam splitter prism B2. The second optical path includes: a broadband polarizing beam splitter prism A1, a Faraday rotator B6, a liquid crystal electronically controlled delay unit B8, and a broadband polarizing beam splitter prism B2. The optical circulator further includes: an electrically controlled rotary displacement stage A9 for supporting and adjusting the angle between the fast axis and the x-axis of the liquid crystal electronically controlled delay unit A7, and an electrically controlled rotary displacement stage B10 for supporting and adjusting the angle between the fast axis and the x-axis of the liquid crystal electronically controlled delay unit B8. The optical circulator also includes a first port 51, a second port 54, a third port 52, a fourth port 53, an optical power meter A12, and an optical power meter B13; The first port 51 and the third port 52 are used to receive light transmitted or emitted from the broadband polarization beam splitter A1. The second port 54 and the fourth port 53 are used to receive light transmitted or emitted from the broadband polarization beam splitter B2. The optical power meter A12 and the optical power meter B13 are used to detect the output optical power of the second port 54 and the fourth port 53; The optical circulator also includes a dual-channel liquid crystal driver 11; The dual-channel liquid crystal driver 11 is used to control the phase delay of the liquid crystal electronically controlled delay unit A7 and the liquid crystal electronically controlled delay unit B8 respectively.

[0027] In practical applications, the spatial optical circulator described in this embodiment can interact with the host computer 14, receive signals collected by the optical power meter A12 and optical power meter B13, and send control signals to the electrically controlled rotary stage A9, the dual-channel liquid crystal driver 11, and the electrically controlled rotary stage B10. This allows for control of the phase delay of the liquid crystal electrically controlled delay units A7 and B8, as well as the adjustment of their fast axis and x-axis angles. Figure 1 .

[0028] The specific implementation examples are as follows: The first port 51 is input to the second port 54.

[0029] For the beam incident at the first port 51, the reflected s-beam reaches the Faraday rotator A5. After the Faraday rotator A5 rotates the vibration direction of the s-beam, it reaches the liquid crystal electronically controlled delay unit A7. The electronically controlled rotary displacement stage A9 controls the initial angle between the fast axis and the x-axis of the liquid crystal electronically controlled delay unit A7. The dual-channel liquid crystal driver 11 controls and sets the phase delay of the liquid crystal electronically controlled delay unit A7, so that the vibration direction of the light after passing through the liquid crystal electronically controlled delay unit A7 is rotated again, and the phase difference with the s-beam is π / 2, so it becomes the p-beam. After passing through the broadband polarization beam splitter B2, it is transmitted to the second port 54. The optical power meter B13 detects the optical power of the second port 54 and sends it to the host computer 14.

[0030] The incident beam at the first port 51, the transmitted p-beam, rotates in the vibration direction after passing through the Faraday rotator B6. The electrically controlled rotary stage B10 controls and adjusts the initial angle between the fast axis and the x-axis of the liquid crystal electrically controlled delay unit B8. The dual-channel liquid crystal driver 11 controls and adjusts the phase delay of the liquid crystal electrically controlled delay unit B8, so that the vibration direction of the light after passing through the liquid crystal electrically controlled delay unit B8 rotates again, and the phase difference with the p-beam is π / 2, becoming s-beam. After passing through the broadband polarization beam splitter B2, it reaches the second port 54. The optical power meter A12 monitors the power of the fourth port 53 and feeds it back to the host computer 14. The host computer 14 drives the dual-channel liquid crystal driver 11, the electrically controlled rotary stage A9, and the electrically controlled rotary stage B10 by comparing the feedback values ​​of the two power meters, so as to realize the switching between the second port 54 and the fourth port 53.

[0031] When the input from the first port 51 to the fourth port 53, the host computer 14 only needs to control the electrically controlled rotary displacement stage A9 and the electrically controlled rotary displacement stage B10 to further control the angle between the fast axis and the x-axis of the liquid crystal electrically controlled delay unit A7 and the liquid crystal electrically controlled delay unit B8. At this time, the s-light of the reflection branch is still s-light after passing through the Faraday rotator A5 and the liquid crystal electrically controlled delay unit A7, and the p-light of the transmission branch is still p-light after passing through the Faraday rotator B6 and the liquid crystal electrically controlled delay unit B8. After passing through the broadband polarizing beam splitter B2, it reaches the fourth port 53.

[0032] In this embodiment, the optical signal can be transmitted through communication unit A15, communication unit B16, optical transceiver A17, and optical transceiver B18, such as Figure 1 .

[0033] In this embodiment, the optical circulator monitors the port power using optical power meters A12 and B13 and feeds it back to the host computer 14 to adjust the angle between the fast axis and the x-axis of the liquid crystal electronically controlled delay device and the phase shift of the liquid crystal electronically controlled delay device. This allows for adjustment of the polarization state of the two optical beams in the spatial optical circulator, thereby enabling port switching.

[0034] Specifically: In this embodiment, when the first port 51 is input to the second port 54, the third port 52 is input to the fourth port 53, the second port 54 is input to the third port 52, and the fourth port 53 is input to the first port 51, the Faraday rotator A5 and the liquid crystal electronically controlled delay unit A7 in the first optical path cooperate to adjust the phase difference of the optical signal by π / 2, and the Faraday rotator B6 and the liquid crystal electronically controlled delay unit B8 in the second optical path cooperate to adjust the phase difference of the optical signal by π / 2.

[0035] When the first port 51 is input to the fourth port 53, the third port 52 is input to the second port 54, the fourth port 53 is input to the third port 52, and the second port 54 is input to the first port 51, the Faraday rotator A5 and the liquid crystal electronically controlled delay unit A7 in the first optical path cooperate to adjust the phase difference of the optical signal to 0, and the Faraday rotator B6 and the liquid crystal electronically controlled delay unit B8 in the second optical path cooperate to adjust the phase difference of the optical signal to 0.

[0036] In actual use, depending on the application scenario, the Faraday rotator and the liquid crystal electronically controlled delay unit in the two optical paths can be controlled by the host computer 14 to achieve the output of different ports and realize the dynamic adjustment of the ports.

[0037] In this embodiment, when the spatial optical circulator is used, a common port can be used between the incident port and the output port. That is, the optical signal enters the optical circulator from the incident port to the common port, and the common port receives the optical signal and simultaneously outputs the optical signal to the output port to realize bidirectional independent optical path transmission. In this embodiment, each port can be used as an output terminal, a common terminal, and an output terminal.

[0038] Implementation Method 2: This implementation method is an optimized design of a spatial optical circulator with a switchable automatic feedback port as described in Implementation Method 1. In this implementation method, the broadband polarization beam splitter A1 and the broadband polarization beam splitter B2 have the same operating wavelength, and their coverage range is 1525~1570nm. The Faraday rotator A5 and the Faraday rotator B6 have the same operating wavelength, covering a range of 1500~1600nm.

[0039] In the optical circulator described in this embodiment, each optical path has a broadband polarizing prism and a Faraday rotator working together to adjust the beam. The working wavelength range of the broadband polarizing beam splitter in this embodiment is 1525~1570nm.

[0040] The Faraday rotator operates in the wavelength range of 1500~1600nm.

[0041] The two work together to achieve coverage of light signals with arbitrary polarization states in the wavelength range of 1530-1570nm, making them suitable for more scenarios.

[0042] Implementation Method 3: This implementation method is an optimized design of a spatial optical circulator with switchable automatic feedback ports as described in Implementation Method 1. In this implementation method, the optical rotation angle between Faraday rotator A5 and Faraday rotator B6 is 45±0.5°. The fast axis of the liquid crystal electronically controlled delay unit A7 forms an angle of 22.5° or 67.5° with the x-axis; The fast axis of the liquid crystal electronically controlled delay unit B8 forms an angle of 22.5° or 67.5° with the x-axis; The liquid crystal electronically controlled delay unit A7 and the liquid crystal electronically controlled delay unit B8 respectively adjust the phase delay of the optical signals in the first optical path and the second optical path to λ / 2.

[0043] In this embodiment, when the first port 51 is input to the second port 54, the third port 52 is input to the fourth port 53, the second port 54 is input to the third port 52, and the fourth port 53 is input to the first port 51, the dual-channel liquid crystal driver 11 controls the liquid crystal electronically controlled delay unit A7 and the liquid crystal electronically controlled delay unit B8 to adjust the phase delay of the optical signal in the first optical path and the second optical path to λ / 2, respectively. Combined with the fast axis of the liquid crystal electronically controlled delay unit A7 forming a 67.5° angle with the x-axis and the fast axis of the liquid crystal electronically controlled delay unit B8 forming a 67.5° angle with the x-axis, the phase difference of the optical signal in the first optical path and the second optical path is adjusted to π / 4 through the cooperation of the Faraday rotator and the liquid crystal electronically controlled delay unit. Combined with the Faraday rotator, the phase difference of the optical signal is adjusted to π / 2, thereby realizing the switching of ports.

[0044] When the first port 51 is input to the fourth port 53, the third port 52 is input to the second port 54, the fourth port 53 is input to the third port 52, and the second port 54 is input to the first port 51, the dual-channel liquid crystal driver 11 controls the liquid crystal electronically controlled delay unit A7 and the liquid crystal electronically controlled delay unit B8 to adjust the phase delay of the optical signals in the first optical path and the second optical path to λ / 2, respectively. Combined with the fast axis of the liquid crystal electronically controlled delay unit A7 being at 22.5° with the x-axis, the fast axis of the liquid crystal electronically controlled delay unit is at 22.5° with the x-axis, so that the Faraday rotator and the liquid crystal electronically controlled delay unit cooperate to adjust the phase difference of the optical signal to 0.

[0045] In actual use, the host computer 14 is electrically connected to the electrically controlled rotary displacement stage A9, the dual-channel liquid crystal driver 11, and the electrically controlled rotary displacement stage B10 to adjust the phase difference of the optical signal.

[0046] In this embodiment, the host computer 14 controls the dual-channel liquid crystal driver 11 to further control the liquid crystal electronically controlled delay unit A7 and the liquid crystal electronically controlled delay unit B8 so that the phase delay of the optical signal in the corresponding optical path is λ / 2.

[0047] Implementation Method Four: Refer to Figure 1 This embodiment describes an optimized design of a spatial optical circulator with a switchable automatic feedback port as described in Embodiment 1. In this embodiment, a plane mirror A3 is provided on the optical path between the broadband polarizing beam splitter A1 and the Faraday rotator A5 to adjust the direction of the optical path. A plane mirror B4 is disposed on the optical path between the broadband polarizing beam splitter B2 and the liquid crystal electronically controlled delay unit B8 to adjust the direction of the optical path.

[0048] In this embodiment, in order to reduce the size of the optical circulator, two reflectors are configured: a plane reflector A3 and a plane reflector B4. The plane reflector A3 is used to receive and reflect the optical signal to the broadband polarizing beam splitter A1 or the Faraday rotator A5; the plane reflector B4 is used to receive and reflect the optical signal to the broadband polarizing beam splitter B2 or the liquid crystal electronically controlled delay device B8. To further reduce the size, the Faraday rotator A5, the liquid crystal electronically controlled delay unit A7, the broadband polarizing beam splitter B2, and the optical power meter B13 in the first optical path are arranged in a straight line.

[0049] The broadband polarizing beam splitter A1, Faraday rotator B6, liquid crystal electronically controlled delay unit B8, broadband polarizing beam splitter B2, and optical power meter A12 in the second optical path are arranged in a straight line.

[0050] Furthermore, the straight lines formed by the two parts are parallel to each other.

[0051] Implementation Method 5: This implementation method is an optimized design of a spatial optical circulator with a switchable automatic feedback port as described in Implementation Method 4. In this implementation method, the reflectivity of the plane mirror A3 and the plane mirror B4 is the same, both greater than 95%.

[0052] In this embodiment, by limiting the reflectivity of both the plane mirror A3 and the plane mirror B4 to be greater than 95%, the overall transmittance of the system reaches 80%, thereby further reducing system losses.

[0053] Implementation Method Six: This implementation method is an optimized design of a spatial optical circulator with a switchable automatic feedback port as described in Implementation Method Four. In this implementation method, the plane mirror A3 and the plane mirror B4 have the same operating wavelength, covering a range of 800~2000nm.

[0054] In this embodiment, the plane mirrors A3 and B4 operate in wavelengths ranging from 800 to 2000 nm. Combined with the broadband polarizing beam splitter prism, the operating wavelength range is 1525 to 1570 nm.

[0055] The Faraday rotator operates in the wavelength range of 1500~1600nm.

[0056] The optical circulator described in this embodiment can achieve coverage of lasers with arbitrary polarization states within the wavelength range of 1530-1570nm.

[0057] Implementation Method Seven: Refer to Figure 1 and Figure 2 This embodiment describes a method for automatically switching the feedback port of a space optical circulator, wherein the space optical circulator is the automatically switchable feedback port space optical circulator described in any one of embodiments one through six. The method includes the following steps: When the light beam is incident from the first port 51 or the third port 52 to the second port 54 or the fourth port 53; The broadband polarizing beam splitter A1 splits the optical signal into light A19 and light B21, which are respectively incident on the first optical path and the second optical path. The light A19 is incident on the optical power meter B13 through the first optical path, and the light B21 is incident on the optical power meter A12 through the second optical path; The optical power outputs of optical power meter A12 and optical power meter B13 are collected in real time, and the angle between the fast axis and the x-axis of the liquid crystal electronically controlled delay unit A7 and the liquid crystal electronically controlled delay unit B8 are controlled according to the optical power. When the light beam is input from the first port 51 to the second port 54, or the light beam is input from the third port 52 to the fourth port 53, the angle between the fast axis and the x-axis of the liquid crystal electronically controlled delay unit A7 and the liquid crystal electronically controlled delay unit B8 is controlled to be 67.5°. When the light beam is input from the first port 51 to the fourth port 53, or from the third port 52 to the second port 54, the host computer 14 controls the fast axis of the liquid crystal electronically controlled delay unit A7 and the liquid crystal electronically controlled delay unit B8 to be 22.5° with the x-axis. When the light beam is input from the second port 54 or the fourth port 53 to the first port 51 or the third port 52; The broadband polarizing beam splitter B2 splits the optical signal into light C20 and light D22, which are respectively incident on the first optical path and the second optical path. Control the angle between the fast axis and the x-axis of the liquid crystal electronically controlled delay unit A7 and the liquid crystal electronically controlled delay unit B8; When the light path exits to the first port 51, the light C20 is s light when it passes through the first light path to the broadband polarization beam splitter A1, and the light D22 is p light when it passes through the second light path to the broadband polarization beam splitter A1. When the light path exits to the third port 52, the light C20 is p-light when it passes through the first optical path to the broadband polarization beam splitter A1, and the light D22 is s-light when it passes through the second optical path to the broadband polarization beam splitter A1.

[0058] When the optical circulator described in this embodiment is input from the first port 51 or the third port 52 to the second port 54 or the fourth port 53: The optical signal is split into light A19 and light B21 by the broadband polarization beam splitter A1. Light A19 enters the first optical path and is transmitted through the Faraday rotator A5 and the liquid crystal electronically controlled delay unit A7 to the broadband polarization beam splitter B2. Then, it is transmitted through the broadband polarization beam splitter B2 to the second port 54 or reflected to the fourth port 53.

[0059] Light B21 enters the second optical path, passes through the Faraday rotator B6 and the liquid crystal electronically controlled delay unit B8, and then passes through the broadband polarizing beam splitter B2. It is then transmitted through the broadband polarizing beam splitter B2 to the fourth port 53 or reflected to the second port 54.

[0060] When the input from the second port 54 or the fourth port 53 is connected to the first port 51 or the third port 52: The optical signal is split into light C20 or light D22 by the broadband polarization beam splitter B2. The light C20 enters the first optical path and is transmitted sequentially through the liquid crystal electronically controlled delay unit A7 and the Faraday rotator A5 to the broadband polarization beam splitter A1. Then, it is transmitted through the broadband polarization beam splitter A1 to the third port 52 or reflected to the first port 51. Light D22 enters the second optical path and is transmitted sequentially through the liquid crystal electronically controlled delay unit B8 and the Faraday rotator B6 to the broadband polarizing beam splitter A1. Then, it is transmitted through the broadband polarizing beam splitter A1 to the first port 51 or reflected to the third port 52. In this embodiment, each port can be used as an output port, a common port, and an output port.

[0061] Implementation Method 8: This implementation method is an optimized design of the method for automatically switching the feedback port of a spatial optical circulator described in Implementation Method 7. In this implementation method, the power ratio of the optical power meter at the output port to the optical power meter at the non-output port is greater than 1000:1.

Claims

1. A spatial optical circulator with an automatically switchable feedback port, characterized in that, The optical circulator contains: The first optical path includes: a broadband polarizing beam splitter prism A (1), a Faraday rotator A (5), a liquid crystal electronically controlled delay unit A (7), and a broadband polarizing beam splitter prism B (2). The second optical path includes: a broadband polarizing beam splitter prism A (1), a Faraday rotator B (6), a liquid crystal electronically controlled delay unit B (8), and a broadband polarizing beam splitter prism B (2). An electrically controlled rotary displacement stage A (9) is used to support and adjust the angle between the fast axis and the x-axis of the liquid crystal electrically controlled delay device A (7); An electrically controlled rotary displacement stage B (10) is used to support and adjust the angle between the fast axis and the x-axis of the liquid crystal electrically controlled delay device B (8); A dual-channel liquid crystal driver (11) is used to control the phase delay of the liquid crystal electronic delay unit A (7) and the liquid crystal electronic delay unit B (8) respectively; First port (51), second port (54), third port (52), fourth port (53), optical power meter A (12) and optical power meter B (13); The first port (51) and the third port (52) are used to receive light transmitted or emitted from the broadband polarization beam splitter A (1). The second port (54) and the fourth port (53) are used to receive light transmitted or emitted from the broadband polarization beam splitter B (2). The optical power meter A (12) and the optical power meter B (13) are used to detect the output optical power of the second port (54) and the fourth port (53), respectively.

2. The spatial optical circulator with switchable automatic feedback port according to claim 1, characterized in that, The broadband polarizing beam splitter A (1) and the broadband polarizing beam splitter B (2) have the same working wavelength, and their coverage range is 1525~1570nm. The Faraday rotator A (5) and the Faraday rotator B (6) have the same operating wavelength, and their coverage range is 1500~1600nm.

3. A spatial optical circulator with switchable automatic feedback port according to claim 1, characterized in that, The optical rotation angle between the Faraday rotator A (5) and the Faraday rotator B (6) is 45 ± 0.5°; The fast axis of the liquid crystal electronically controlled delay unit A (7) forms an angle of 22.5° or 67.5° with the x-axis; The fast axis of the liquid crystal electronically controlled delay unit B (8) forms an angle of 22.5° or 67.5° with the x-axis; The liquid crystal electronically controlled delay device A (7) and the liquid crystal electronically controlled delay device B (8) respectively adjust the phase delay of the optical signals in the first optical path and the second optical path to λ / 2.

4. A spatial optical circulator with switchable automatic feedback port according to claim 1, characterized in that, A plane mirror A (3) is provided on the optical path between the broadband polarizing beam splitter A (1) and the Faraday rotator A (5) to adjust the direction of the optical path; A plane mirror B (4) is provided on the optical path between the broadband polarizing beam splitter B (2) and the liquid crystal electronically controlled delay device B (8) to adjust the direction of the optical path.

5. A spatial optical circulator with switchable automatic feedback port according to claim 4, characterized in that, The reflectivity of the plane mirror A (3) and the plane mirror B (4) is the same, both greater than 95%.

6. A spatial optical circulator with switchable automatic feedback port according to claim 4, characterized in that, The plane mirror A (3) and the plane mirror B (4) have the same working wavelength, covering a range of 800~2000nm.

7. A method for automatically switching the feedback port of a spatial optical circulator, characterized in that, The spatial optical circulator is the automatically feedback port-switchable spatial optical circulator as described in any one of claims 1 to 6, and the method includes the following steps: When the light beam is incident from the first port (51) or the third port (52) to the second port (54) or the fourth port (53); A broadband polarizing beam splitter A (1) splits the optical signal into light A (19) and light B (21), which are respectively incident on the first optical path and the second optical path; The light A (19) is incident on the optical power meter B (13) through the first optical path, and the light B (21) is incident on the optical power meter A (12) through the second optical path. The optical power output of optical power meter A (12) and optical power meter B (13) is collected in real time, and the angle between the fast axis and the x-axis of the liquid crystal electronic delay unit A (7) and the angle between the fast axis and the x-axis of the liquid crystal electronic delay unit B (8) are controlled according to the optical power. When the light beam is input from the first port (51) to the second port (54), or the light beam is input from the third port (52) to the fourth port (53), the angle between the fast axis and the x-axis of the liquid crystal electronically controlled delay device A (7) and the liquid crystal electronically controlled delay device B (8) is 67.5°. When the light beam is input from the first port (51) to the fourth port (53) or from the third port (52) to the second port (54), the angle between the fast axis and the x-axis of the liquid crystal electronically controlled delay device A (7) and the liquid crystal electronically controlled delay device B (8) is 22.5°. When the beam is input from the second port (54) or the fourth port (53) to the first port (51) or the third port (52); The broadband polarizing beam splitter B(2) splits the optical signal into light C(20) and light D(22), which are respectively incident on the first optical path and the second optical path; Control the angle between the fast axis and the x-axis of the liquid crystal electronic delay unit A (7) and the liquid crystal electronic delay unit B (8); When the light path exits to the first port (51), the light C (20) is s light when it passes through the first light path to the broadband polarization beam splitter A (1), and the light D (22) is p light when it passes through the second light path to the broadband polarization beam splitter A (1). When the light path exits to the third port (52), the light C (20) is p light when it passes through the first light path to the broadband polarization beam splitter A (1), and the light D (22) is s light when it passes through the second light path to the broadband polarization beam splitter A (1).

8. The method for automatically switching the feedback port of a spatial optical circulator according to claim 7, characterized in that, The power ratio of the optical power meter controlling the output port to the optical power meter controlling the non-output port is greater than 1000:1.

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