Three-port reflection type optical circulator

Abstract

The invention discloses a three-port reflective optical circulator, which belongs to the field of optical communication, and comprises a first polarization splitting prism assembly, a half-wave plate, a Faraday optical rotation crystal and a second polarization splitting prism assembly which are arranged in sequence, and the joint of two first prisms of the first polarization splitting prism assembly is plated with a polarization splitting film; the connection position of two second prisms of the second polarization splitting prism assembly is plated with a polarization splitting film, the first port, the second port and the third port are located on one side of the first polarization splitting prism assembly, the first port is located between the second port and the third port, and light splitting and light combination are carried out through the polarization splitting prism assembly. The half-wave plate and the Faraday optical rotation crystal control the polarization direction of the sub light beams, the functions of first port input, second port output, second port input and third port output of the optical circulator are achieved, the three ports are located on the same side, other parts are convenient to place, and the optical circulator can be miniaturized.

Description

Technical Field

[0001] The invention relates to the field of optical communication, in particular to a three-port reflective optical circulator. Background Art

[0002] Optical circulator is a very important non-reciprocal optical passive device with multi-port input and output in fiber-optic communication systems. Its function is to make the optical signal only be transmitted in a ring along the specified port sequence. It has the characteristics of forward sequential transmission and reverse sequential isolation, and can complete the separation of forward and reverse transmission light. Therefore, it is widely used in single-fiber bidirectional transmission systems, fiber Bragg grating-based dense wavelength division multiplexers, optical amplifiers, optical time domain reflectometers, as well as in traditional fields such as fiber sensing and fiber testing.

[0003] The three ports of the 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 when designing the optical path, resulting in the inability to miniaturize the optical circulator. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, one of the objectives of the present invention is to provide a 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, wherein the first polarization beam splitter prism assembly comprises two first prisms, each of the first prisms comprises 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 comprises two second prisms, one of the second prisms comprises two parallel sides, the other of the second prisms comprises 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 at 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 working, 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 is directly transmitted through one of the first prisms, the s-polarized light is first reflected at the polarization beam splitter film, and then is totally reflected through 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, and the s-polarized light is reflected at 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, the p-polarized light passes through the polarization beam splitter film and then directly transmits through one of the second prisms and reflects at the parallel edge, and the s-polarized light is reflected at the polarization beam splitter film; when passing through the Faraday rotator crystal, the p-polarized light and the s-polarized light are both 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 emission; the s-polarized light is rotated 135° counterclockwise and converted into p-polarized light for emission; 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, and after being transmitted through the polarization beam splitter film, it is reflected to the third port at the parallel edge of another of the first prisms; and the s-polarized light is reflected from the polarization beam splitter film and then reflected to the third port at the parallel edge of another of the first prisms.

[0009] Furthermore, the two first prisms are two quadrilateral prisms.

[0010] Furthermore, the two first prisms are two parallelogram prisms.

[0011] Furthermore, the overall 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] Further, 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 also includes a first single-fiber collimator, and the first single-fiber collimator is located at the first port.

[0016] Furthermore, the reflective optical circulator also includes a second single-fiber collimator, and the second single-fiber collimator is located at the second port.

[0017] Furthermore, the reflective optical circulator also 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 also includes a filter, and the filter is located between the second single-fiber collimator and the second polarization beam splitter prism assembly.

[0019] Compared with the prior art, the three-port reflective optical circulator of the present application includes a first polarization beam splitter prism assembly, a half-wave plate, a Faraday rotator crystal, and a second polarization beam splitter prism assembly which are arranged in sequence. The first polarization beam splitter prism assembly includes two first prisms, each of which includes two parallel sides, and a polarization beam splitter film is plated at the connection between the two first prisms. The second polarization beam splitter prism assembly includes two second prisms, one second prism includes two parallel sides, and the other second prism includes two sides forming an acute angle, and a polarization beam splitter film is plated 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. Through the above design, light is split and combined through the polarization beam splitter prism assembly, and the half-wave plate and the Faraday rotator crystal control the polarization direction of the sub-beam, so as to realize the functions of the optical circulator inputting at the first port and outputting at the second port and the second port inputting at the third port, so that the three ports are located on the same side of the optical circulator, so that other components are easy to place, and the optical circulator can be miniaturized. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of a three-port reflective optical circulator of the present invention;

[0021] Figure 2 for Figure 1 A light path diagram of a three-port reflective optical circulator in which light enters from a first port and exits from a second port;

[0022] Figure 3 for Figure 1 The optical path diagram of the three-port reflective optical circulator is that light enters from the second port and exits from the third port.

[0023] In the figure: 105, a first single-fiber collimator; 104, a first polarization beam splitter prism assembly; 103, a half-wave plate; 102, a Faraday rotator crystal; 101, a second polarization beam splitter prism assembly; 106, a second single-fiber collimator; 107, a third single-fiber collimator; 108, a filter. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[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 those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[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 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, and is used to receive the light beam when the optical path from the first port to the second port is in operation. 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 includes two parallel sides, and a polarization beam splitter film is coated at the connection between the two first prisms. 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 polarization beam splitter prism assembly 101 includes two second prisms, one second prism includes two parallel sides, the other second prism includes two sides forming an acute angle, and the connection between the two second prisms is coated with a polarization 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, the triangular prism is an isosceles triangle, and the overall cross-section of the second polarization 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 the parallel light beam passes through the first polarization beam splitter prism assembly 104, the parallel light beam is decomposed into two sub-beams of p-polarized light and s-polarized light with orthogonal polarization directions. The p-polarized light can be directly transmitted after passing 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 at the polarization beam splitter film between the two first prisms of the first polarization beam splitter prism assembly 104, and then undergoes total 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 rotate 45° clockwise along the incident light direction. At this time, the originally p-polarized beam still maintains the p-polarized state and the s-polarized beam also maintains the s-polarized state.

[0038] After being split by the second polarization beam splitter prism assembly 101, the p-polarized light is directly transmitted through the polarization beam splitter film, while the s-polarized light is reflected on the polarization beam splitter film. In the optical path, the p-polarized light is first totally reflected at the interface between the parallelogram-shaped second prism below the second polarization beam splitter prism assembly 101 and the air, and then transmitted through the polarization beam splitter film between the two second prisms of the second polarization beam splitter prism assembly 101, and then totally reflected at the interface between the parallelogram-shaped second prism above the second polarization beam splitter prism assembly 101 and the air, and finally guided to the filter 108. At the same time, the s-polarized light is first reflected at the polarization beam splitter film between the two second prisms of the second polarization beam splitter prism assembly 101, and then totally reflected at the interface between the triangular second prism above the second polarization beam splitter prism assembly 101 and the air, and also guided to the filter 108. The optical filter 108 can prevent the transmission of unnecessary light, selectively pass the light in a specific wavelength range, and finally transmit it to the second single-fiber collimator 106 (ie, the second port).

[0039] When the optical circulator is in the second port P2->third port P3 optical path, 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, the filter 108 can prevent the transmission of unnecessary light and selectively pass the light within a specific wavelength range. After the parallel light beam passes through the second polarization beam splitter prism assembly 101, the parallel light beam is decomposed into two sub-beams of p-polarized light and s-polarized light with orthogonal polarization directions. The p-polarized light can be directly transmitted after passing through the polarization beam splitter film between the two second prisms of the second polarization beam splitter prism assembly 101, and then is transmitted along the lower optical path after total reflection occurs at the interface between the parallelogram-shaped second prism below the second polarization beam splitter prism assembly 101 and the external air. The s-polarized light is first reflected at the polarization beam splitter film between the two second prisms of the second polarization beam splitter prism assembly 101, and is transmitted along the upper optical path;

[0042] After the Faraday rotator crystal 102 is applied, 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 the s-polarized light beam is converted into p-polarized light.

[0044] After the light is combined through the first polarization beam splitter prism assembly 104, 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 on the polarization beam splitter film. In the optical path, the p-polarized light first undergoes total 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 reflection at the interface between the parallelogram-shaped first prism below the first polarization beam splitter prism assembly 104 and the external air, and then is transmitted to the third single-fiber collimator 107 (i.e., the third port). The s-polarized light is first reflected at the polarization beam splitter films of the two first prisms of 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 uses the layout of polarization beam splitter prism components to achieve an integrated layout of all ports on the same side. Compared with the mode in which the optical circulator ports are located on both sides for transmission in the traditional design, 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 changeable, reduces the occupation of system space, but also further improves the integration of the system 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 only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which are equivalent modifications and improvements made to the above embodiments based on the essential technology of the present invention, and all of them belong to the protection scope of the present invention.

Claims

1. A three-port reflective optical circulator, comprising a first port, a second port and a third port, wherein: 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 which are 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 of the second prisms 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. When the optical path from the first port to the second port is working, 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 is directly transmitted through one of the first prisms, the s-polarized light is first reflected at the polarization beam splitter film, and then is totally reflected through 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, and the s-polarized light is reflected at 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, the p-polarized light passes through the polarization beam splitter film and then directly transmits through one of the second prisms and reflects at the parallel edge, and the s-polarized light is reflected at the polarization beam splitter film; when passing through the Faraday rotator crystal, the p-polarized light and the s-polarized light are both 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 emission; the s-polarized light is rotated 135° counterclockwise and converted into p-polarized light for emission; 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, and after being transmitted through the polarization beam splitter film, it is reflected to the third port at the parallel edge of another of the first prisms; and the s-polarized light is reflected from the polarization beam splitter film and then reflected to the third port at the parallel edge of another of the first prisms.

2. The three-port reflective optical circulator according to claim 1, characterized in that: The two first prisms are two quadrilateral prisms.

3. The three-port reflective optical circulator according to claim 2, characterized in that: The two first prisms are two parallelogram prisms.

4. The three-port reflective optical circulator according to claim 3, characterized in that: The first polarization beam splitter prism assembly has an overall cross-section of a parallelogram.

5. The three-port reflective optical circulator according to claim 2, characterized in that: The two second prisms are a quadrilateral prism and a triangular prism.

6. The three-port reflective optical circulator according to claim 5, characterized in that: The overall cross-section of the second polarization beam splitter prism assembly is an isosceles trapezoid.

7. The three-port reflective optical circulator according to claim 5, characterized in that: 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.

8. The three-port reflective optical circulator according to claim 1, characterized in that: The reflective optical circulator further includes a first single-fiber collimator, and the first single-fiber collimator is located at the first port.

9. The three-port reflective optical circulator according to claim 1, characterized in that: The reflective optical circulator further includes a second single-fiber collimator, and the second single-fiber collimator is located at the second port.

10. The three-port reflective optical circulator according to claim 1, characterized in that: The reflective optical circulator further includes a third single-fiber collimator, and the third single-fiber collimator is located at the third port.

11. The three-port reflective optical circulator according to claim 1, characterized in that: 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.

Images