Three-port reflective optical circulator
By designing the ports of a three-port reflective optical circulator on the same side and using a polarization beam splitter prism assembly and a half-wave plate to control the direction of the optical signal, the structural redundancy problem of the existing optical circulator is solved, and the miniaturization and flexible application of the optical circulator are achieved.
Patent Information
- Application Number
- CN202510057325.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-14
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2045-01-14
AI Technical Summary
The existing three-port reflective optical circulator has ports located on different sides, resulting in structural redundancy, inability to be miniaturized, and complex optical path design.
A three-port reflective optical circulator with three ports located on the same side was designed. A first polarization beam splitter prism assembly, a half-wave plate, a Faraday rotator crystal, and a second polarization beam splitter prism assembly were arranged in sequence. Polarization splitting and polarization direction control were used to achieve forward sequential transmission and reverse isolation of optical signals. The layout of the polarization beam splitter prism assembly was used to achieve an integrated layout of the ports.
The miniaturization of the optical circulator is achieved, the integration and spatial configuration flexibility of the optical transmission system are improved, the system space occupation is reduced, and the application scenarios are broadened.
Smart Images
Figure CN119805797B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of optical communications, in particular to a three-port reflective optical circulator. Background Art
[0002] An optical circulator is a very important multi-port input and output non-reciprocal optical passive device in fiber-optic communication systems. Its function is to transmit optical signals in a circular manner only along a specified port sequence. It has the characteristics of forward sequential transmission and reverse sequential isolation, which can complete the separation of forward and reverse transmitted light. Therefore, it has a wide range of applications in single-fiber bidirectional transmission systems, fiber Bragg grating-based dense wavelength division multiplexers, optical amplifiers, optical time-domain reflectometers, and traditional fields such as fiber sensing and fiber testing.
[0003] The three ports of an existing three-port reflective optical circulator are located on different sides of the circulator. This structure not only leads to structural redundancy, but also requires consideration of the placement of components in the module during optical path design, making it impossible to miniaturize the optical circulator. Summary of the Invention
[0004] In order to overcome the deficiencies of the prior art, one of the objectives of the present invention is to provide a three-port reflective optical circulator in which the three ports are located on the same side of the optical circulator.
[0005] One of the purposes of the present invention is achieved by the following technical solution:
[0006] A three-port reflective optical circulator is provided with a first port, a second port, a third port, a first polarization beam splitter prism assembly, a half-wave plate, a Faraday rotator crystal, and a second polarization beam splitter prism assembly arranged in sequence. The first polarization beam splitter prism assembly includes two first prisms, each of the first prisms includes two parallel sides, and a polarization beam splitter film is coated at the connection between the two first prisms. The second polarization beam splitter prism assembly includes two second prisms, one of the second prisms includes two parallel sides, and the other second prism includes two sides forming an acute angle, and a polarization beam splitter film is coated at the connection between the two second prisms. The first port, the second port, and the third port are located on one side of the first polarization beam splitter prism assembly, and the first port is located between the second port and the third port.
[0007] When the optical path from the first port to the second port is in operation, the first polarization beam splitter prism assembly decomposes the incident light at the first port into two sub-beams of p-polarized light and s-polarized light with orthogonal polarization directions. The p-polarized light passes through the polarization beam splitter film and directly transmits through one of the first prisms. The s-polarized light is first reflected at the polarization beam splitter film and then totally reflected by the edge of the other first prism. When passing through the half-wave plate, the p-polarized light rotates 135° clockwise and the s-polarized light rotates 45° counterclockwise. When passing through the Faraday rotator crystal, both the p-polarized light and the s-polarized light rotate 45° clockwise. When passing through the second polarization beam splitter prism assembly, the p-polarized light is reflected at the parallel edge of one of the second prisms and then passes through the polarization beam splitter film and is totally reflected at the acute-angle edge to enter the second port. The s-polarized light is reflected by the polarization beam splitter film and is totally reflected at the acute-angle edge to enter the second port.
[0008] When the optical path from the second port to the third port is working, the second polarization beam splitter prism assembly first reflects the incident light at the second port to the polarization beam splitter film, and the p-polarized light is directly transmitted through the polarization beam splitter film and reflected at the parallel edge of the second prism after passing through the polarization beam splitter film, and the s-polarized light is reflected at the polarization beam splitter film; when passing through the Faraday rotator crystal, both the p-polarized light and the s-polarized light are rotated 45° clockwise, and when passing through the half-wave plate, the p-polarized light is rotated 45° clockwise and converted into s-polarized light for exit; the s-polarized light is rotated 135° counterclockwise and converted into p-polarized light for exit; when passing through the first polarization beam splitter prism assembly, the p-polarized light is first reflected through the parallel edge of one of the first prisms, transmitted through the polarization beam splitter film, and then reflected at the parallel edge of another first prism to the third port; the s-polarized light is reflected at the parallel edge of another first prism after being reflected from the polarization beam splitter film and is reflected to the third port.
[0009] Furthermore, the two first prisms are two quadrilateral prisms.
[0010] Furthermore, the two first prisms are two parallelogram prisms.
[0011] Furthermore, the entire cross-section of the first polarization beam splitter prism assembly is a parallelogram.
[0012] Furthermore, the two second prisms are a quadrilateral prism and a triangular prism.
[0013] Furthermore, the overall cross-section of the second polarization beam splitter prism assembly is an isosceles trapezoid.
[0014] Furthermore, the positions of the first port and the third port correspond to the positions of the two first prisms, and the position of the second port corresponds to the triangular second prism.
[0015] Furthermore, the reflective optical circulator further includes a first single-fiber collimator, and the first single-fiber collimator is located at the first port.
[0016] Furthermore, the reflective optical circulator further includes a second single-fiber collimator, and the second single-fiber collimator is located at the second port.
[0017] Furthermore, the reflective optical circulator further includes a third single-fiber collimator, and the third single-fiber collimator is located at the third port.
[0018] Furthermore, the three-port reflective optical circulator further includes a filter, and the filter is located between the second single-fiber collimator and the second polarization beam splitter prism assembly.
[0019] Compared to the prior art, the present invention provides a three-port reflective optical circulator comprising a first polarization beam splitter prism assembly, a half-wave plate, a Faraday rotator crystal, and a second polarization beam splitter prism assembly, arranged in sequence. The first polarization beam splitter prism assembly comprises two first prisms, each of which comprises two parallel sides, and a polarization beam splitting film is applied to the junction of the two first prisms. The second polarization beam splitter prism assembly comprises two second prisms, one of which comprises two parallel sides, and the other comprises two sides forming an acute angle, and a polarization beam splitting film is applied to the junction of the two second prisms. The first, second, and third ports are located on one side of the first polarization beam splitter prism assembly, with the first port located between the second and third ports. Through this design, the polarization beam splitter prism assembly performs light splitting and light combining, and the half-wave plate and Faraday rotator crystal control the polarization directions of the sub-beams, thereby achieving the optical circulator's functions of input at the first port and output at the second port, and input at the second port and output at the third port. The three ports are located on the same side of the optical circulator, making it easier to arrange other components and miniaturizing the optical circulator. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 Schematic diagram of the structure of the three-port reflective optical circulator of the present invention;
[0021] Figure 2 for Figure 1 A three-port reflective optical circulator having an optical path diagram of light entering from a first port and exiting from a second port;
[0022] Figure 3 for Figure 1 The optical path diagram of a three-port reflective optical circulator where light enters from the second port and exits from the third port.
[0023] In the figure: 105, first single-fiber collimator; 104, first polarization beam splitter prism assembly; 103, half-wave plate; 102, Faraday rotator crystal; 101, second polarization beam splitter prism assembly; 106, second single-fiber collimator; 107, third single-fiber collimator; 108, filter. DETAILED DESCRIPTION
[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0025] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may be another intermediate component through which it is fixed. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be another intermediate component at the same time. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be another intermediate component at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.
[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0027] See also Figure 1 The three-port reflective optical circulator includes a first single-fiber collimator 105, a first polarization beam splitter prism assembly 104, a half-wave plate 103, a Faraday rotator crystal 102, and a second polarization beam splitter prism assembly 101, which are arranged along the optical path. The three-port reflective optical circulator also includes a second single-fiber collimator 106, a third single-fiber collimator 107, and a filter 108. The first single-fiber collimator 105, the second single-fiber collimator 106, and the third single-fiber collimator 107 are located on the same side of the first polarization beam splitter prism assembly 104, and the first single-fiber collimator 105 is located between the second single-fiber collimator 106 and the third single-fiber collimator 107.
[0028] The first single-fiber collimator 105 is located at the first port and is used to collimate the divergent light beam output by the optical fiber into a parallel light beam.
[0029] The second single-fiber collimator 106 is located at the second port. When the optical path from the first port to the second port is in operation, the second single-fiber collimator 106 is used to receive the light beam. When the optical path from the second port to the third port is in operation, the second single-fiber collimator 106 collimates the divergent light beam output by the optical fiber into a parallel light beam.
[0030] The third single-fiber collimator 107 is located at the third port. When the optical path from the second port to the third port is in operation, the third single-fiber collimator 107 is used to receive the light beam.
[0031] The first polarization beam splitter prism assembly 104 includes two first prisms, each of which has two parallel sides. The connection between the two first prisms is coated with a polarization beam splitting film. Specifically, the two first prisms are two quadrilateral prisms. In this embodiment, the two first prisms are two parallelogram prisms. The positions of the first single-fiber collimator 105 and the third single-fiber collimator 107 correspond to the positions of the two first prisms. The overall cross-section of the first polarization beam splitter prism assembly 104 is a parallelogram.
[0032] The second polarizing beam splitter prism assembly 101 includes two second prisms, one of which has two parallel sides, and the other of which has two sides forming an acute angle. The connection between the two second prisms is coated with a polarizing beam splitter film. Specifically, the two second prisms are a quadrilateral prism and a triangular prism. In this embodiment, the quadrilateral prism is a parallelogram, and the triangular prism is an isosceles triangle. The overall cross-section of the second polarizing beam splitter prism assembly 101 is an isosceles trapezoid.
[0033] When the optical circulator is operating in the optical path of the first port P1->second port P2, the propagation direction of the light beam is as follows: Figure 2 As shown, Figure 2 In the figure, blue represents s-polarized light and red represents p-polarized light.
[0034] The divergent light beam outputted by the optical fiber is first collimated into a parallel light beam by the first single-fiber collimator 105;
[0035] After passing through the first polarization beam splitter prism assembly 104, the parallel light beam is split into two sub-beams of p-polarized light and s-polarized light with orthogonal polarization directions. The p-polarized light passes directly through the polarization beam splitter film between the two first prisms of the first polarization beam splitter prism assembly 104 and is transmitted along the lower optical path. The s-polarized light is first reflected by the polarization beam splitter film between the two first prisms of the first polarization beam splitter prism assembly 104, then undergoes total internal reflection at the interface between the parallelogram-shaped first prism and the external air, and is transmitted along the upper optical path.
[0036] After passing through the half-wave plate 103, the polarization direction of the p-polarized light rotates 135° clockwise along the incident light direction, and the polarization direction of the s-polarized light rotates 45° counterclockwise along the incident light direction;
[0037] After passing through the Faraday rotator crystal 102, the polarization directions of the two sub-beams are rotated 45° clockwise along the incident light direction. At this time, the originally p-polarized beam still remains in the p-polarized state, and the s-polarized beam also remains in the s-polarized state.
[0038] After passing through the second polarization beam splitter assembly 101 for splitting, the p-polarized light is directly transmitted through the polarization beam splitting film, while the s-polarized light is reflected by the polarization beam splitting film. In the optical path, the p-polarized light first undergoes total internal reflection at the interface between the parallelogram-shaped second prism below the second polarization beam splitter assembly 101 and the air. It then transmits through the polarization beam splitting film between the two second prisms of the second polarization beam splitter prism assembly 101. It then undergoes total internal reflection at the interface between the parallelogram-shaped second prism above the second polarization beam splitter prism assembly 101 and the air, ultimately being directed toward the optical filter 108. Meanwhile, the s-polarized light first reflects from the polarization beam splitting film between the two second prisms of the second polarization beam splitter prism assembly 101. It then undergoes total internal reflection at the interface between the triangular second prism above the second polarization beam splitter prism assembly 101 and the air, also being directed toward the optical filter 108. The optical filter 108 can prevent the transmission of unnecessary light, selectively pass light within a specific wavelength range, and ultimately transmit the light to the second single-fiber collimator 106 (ie, the second port).
[0039] When the optical circulator is working in the optical path of the second port P2->third port P3, the propagation direction of the light beam is as follows: Figure 3 As shown, Figure 3 In the figure, blue represents s-polarized light and red represents p-polarized light.
[0040] The divergent light beam outputted by the optical fiber is first collimated into a parallel light beam by the second single-fiber collimator 106;
[0041] After the parallel light beam passes through the filter 108, which blocks the transmission of unnecessary light and selectively transmits light within a specific wavelength range, it passes through the second polarization beam splitter prism assembly 101 and is split into two sub-beams of p-polarized light and s-polarized light with orthogonal polarization directions. The p-polarized light is directly transmitted after passing through the polarization beam splitter film between the two second prisms of the second polarization beam splitter prism assembly 101. It then undergoes total internal reflection at the interface between the parallelogram-shaped second prism below the second polarization beam splitter prism assembly 101 and the external air, and then is transmitted along the lower optical path. The s-polarized light is first reflected by the polarization beam splitter film between the two second prisms of the second polarization beam splitter prism assembly 101 and is then transmitted along the upper optical path.
[0042] After passing through the Faraday rotator crystal 102, the polarization directions of the two sub-beams rotate 45° clockwise along the direction of the incident light;
[0043] After passing through the half-wave plate 103, the polarization direction of the p-polarized light rotates 45° clockwise along the direction of the incident light, and the polarization direction of the s-polarized light rotates 135° counterclockwise along the direction of the incident light; at this time, due to the conversion of the polarization state of the light beam relative to the second polarization splitter prism assembly 101, the originally p-polarized light beam is converted into s-polarized light and then emitted, while the s-polarized light beam is converted into p-polarized light and then emitted.
[0044] The light is combined by the first polarization beam splitter prism assembly 104, and the connection between the two first prisms is treated with a polarization beam splitter film. The p-polarized light is directly transmitted through the polarization beam splitter film, while the s-polarized light is reflected by the polarization beam splitter film. In the optical path, the p-polarized light first undergoes total internal reflection at the interface between the first polarization beam splitter prism assembly 104 and the external air, then passes through the polarization beam splitter film between the two first prisms, and then undergoes total internal reflection at the interface between the parallelogram-shaped first prism below the first polarization beam splitter prism assembly 104 and the external air, before being transmitted to the third single-fiber collimator 107 (i.e., the third port). The s-polarized light is first reflected by the polarization beam splitter films of the two first prisms in the first polarization beam splitter prism assembly 104, then is totally reflected at the interface between the parallelogram-shaped first prism below the first polarization beam splitter prism assembly 104 and the air, and finally is also transmitted to the third single-fiber collimator 107 (i.e., the third port).
[0045] The three-port reflective optical circulator of the present application utilizes the layout of polarization beam splitter prism components to achieve an integrated layout of all ports on the same side. Compared to the traditional design in which the optical circulator ports are located on both sides for transmission, the present invention significantly reduces the overall volume of the device. This miniaturized design advantage not only makes the placement of the optical circulator in the optical transmission system more flexible and variable, reducing the space occupied by the system, but also further improves the system's integration and increases the spatial configuration flexibility of the optical circulator in the optical transmission system. Therefore, the optical circulator can play a role in a wider range of application scenarios, broadens its adaptability and potential in actual application scenarios, and provides strong support for the optimization and upgrading of optical transmission systems.
[0046] The above embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patented invention. It should be noted that those skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention. These variations and improvements are equivalent modifications and improvements to the above embodiments based on the essential technology of the present invention and fall within the scope of protection of the present invention.
Claims
1. A three-port reflective optical circulator having a first port, a second port, and a third port, characterized in that: The three-port reflective optical circulator also includes a first polarization beam splitter prism assembly, a half-wave plate, a Faraday rotator crystal, and a second polarization beam splitter prism assembly arranged in sequence. The first polarization beam splitter prism assembly includes two first prisms, each of the first prisms includes two parallel sides, and a polarization beam splitter film is coated at the connection between the two first prisms. The second polarization beam splitter prism assembly includes two second prisms, and the two second prisms are a quadrilateral prism and a triangular prism. The positions of the first port and the third port correspond to the positions of the two first prisms, and the position of the second port corresponds to the triangular second prism. A polarization beam splitter film is coated at the connection between the two second prisms. The first port, the second port, and the third port are located on one side of the first polarization beam splitter prism assembly, and the first port is located between the second port and the third port. When the optical path from the first port to the second port is in operation, the first polarization beam splitter prism assembly decomposes the incident light at the first port into two sub-beams of p-polarized light and s-polarized light with orthogonal polarization directions. The p-polarized light passes through the polarization beam splitter film and directly transmits through one of the first prisms. The s-polarized light is first reflected at the polarization beam splitter film and then totally reflected by the edge of the other first prism. When passing through the half-wave plate, the p-polarized light rotates 135° clockwise and the s-polarized light rotates 45° counterclockwise. When passing through the Faraday rotator crystal, both the p-polarized light and the s-polarized light rotate 45° clockwise. When passing through the second polarization beam splitter prism assembly, the p-polarized light is reflected at the parallel edge of one of the second prisms and then passes through the polarization beam splitter film and is totally reflected at the acute-angle edge to enter the second port. The s-polarized light is reflected by the polarization beam splitter film and is totally reflected at the acute-angle edge to enter the second port. When the optical path from the second port to the third port is working, the second polarization beam splitter prism assembly first reflects the incident light at the second port to the polarization beam splitter film, and the p-polarized light is directly transmitted through the polarization beam splitter film and reflected at the parallel edge of the second prism after passing through the polarization beam splitter film, and the s-polarized light is reflected at the polarization beam splitter film; when passing through the Faraday rotator crystal, both the p-polarized light and the s-polarized light are rotated 45° clockwise, and when passing through the half-wave plate, the p-polarized light is rotated 45° clockwise and converted into s-polarized light for exit; the s-polarized light is rotated 135° counterclockwise and converted into p-polarized light for exit; when passing through the first polarization beam splitter prism assembly, the p-polarized light is first reflected through the parallel edge of one of the first prisms, transmitted through the polarization beam splitter film, and then reflected at the parallel edge of another first prism to the third port; the s-polarized light is reflected at the parallel edge of another first prism after being reflected from the polarization beam splitter film and is reflected to the third port.
2. The three-port reflective optical circulator according to claim 1, wherein: The two first prisms are two quadrilateral prisms.
3. The three-port reflective optical circulator according to claim 2, wherein: The two first prisms are two parallelogram prisms.
4. The three-port reflective optical circulator according to claim 3, wherein: The first polarization beam splitter prism assembly has an overall cross-section in the shape of a parallelogram.
5. The three-port reflective optical circulator according to claim 1, wherein: The overall cross-section of the second polarization beam splitter prism assembly is an isosceles trapezoid.
6. The three-port reflective optical circulator according to claim 1, wherein: The reflective optical circulator further includes a first single-fiber collimator, which is located at the first port.
7. The three-port reflective optical circulator according to claim 1, wherein: The reflective optical circulator further includes a second single-fiber collimator, and the second single-fiber collimator is located at the second port.
8. The three-port reflective optical circulator according to claim 1, wherein: The reflective optical circulator further includes a third single-fiber collimator, and the third single-fiber collimator is located at the third port.
9. The three-port reflective optical circulator according to claim 7, wherein: The three-port reflective optical circulator further includes a filter, which is located between the second single-fiber collimator and the second polarization beam splitter prism assembly.