Polarization dependent reflective two-stage optical circulator

Abstract

The application provides a polarization-dependent reflective two-stage optical ring, which comprises a first collimator, a first beam splitting cube, a first optical rotation component, a second beam splitting cube, a third beam splitting cube of a second optical rotation component and a second collimator arranged along a first optical path, and three beam splitting cubes are respectively light splitting dielectric films; the application combines the characteristics of a transmission two-stage ring and a reflective ring, two optical rotation components are arranged on the first optical path from the first collimator to the second collimator, thereby realizing the series connection of two isolation systems, playing a double-stage isolation effect, meanwhile, the application realizes the optical path folding of a second optical path from the second collimator to the third collimator by using a reflective component, and optical components are multiplexed in one of the optical rotation components, thereby also achieving a double-stage isolation effect; while realizing the double-stage isolation effect, the application also reduces the product volume, is beneficial to the integration of equipment and is also beneficial to cost reduction.

Description

Technical Field

[0001] This invention relates to the field of optical circulator technology, and more particularly to a polarization-dependent reflective two-stage optical circulator. Background Technology

[0002] An optical circulator is a multi-port non-reciprocal passive optical device that allows light to pass through in one direction from any port to the next while blocking light from passing through in the opposite direction. It has the functions of forward optical conduction and reverse isolation.

[0003] In fiber laser systems, in order to utilize the gain to amplify the signal light more efficiently, loops are sometimes designed in the system to multiplex the gain components. In this case, the forward conduction function of the optical circulator is required to allow the light to enter and exit the system loop in a specific direction from any port to the next port.

[0004] According to the design of fiber laser systems, strong backlighting can easily cause instability, performance degradation, and even burn out the entire system. Therefore, protective devices with unidirectional conduction and reverse isolation are needed in fiber laser systems. Circulators, due to their combined looping and reverse blocking functions, are widely used in some laser systems.

[0005] There are two main types of circulators in the current technology. One is the transmissive two-stage circulator, which generally adopts a linear design and achieves two-stage isolation through two isolation systems connected in series. However, the transmissive two-stage circulator has the following disadvantages: the two-stage isolation effect only exists in one path, such as the optical path from port 1 to port 2, while the other path, such as the optical path from port 2 to port 3, only has a single-stage isolation effect. If both-stage isolation is required simultaneously, three isolation systems are needed, connected in series in pairs. The overall device size is large and the cost is high.

[0006] Another type is the reflective circulator, which uses a high-reflectivity coating to achieve optical path folding and reuse optical components such as Faraday rotators. It achieves the effect of double-stage isolation with only one isolation system. However, the optical path design of this circulator can only satisfy one optical path, such as the optical path from port 1 to port 2, through the folded optical path to achieve the effect of double-stage isolation, while the other optical path, such as the optical path from port 2 to port 3, does not pass through the folded optical path and only has the effect of single-stage isolation. Summary of the Invention

[0007] The purpose of this invention is to provide a polarization-dependent reflective two-stage optical circulator.

[0008] To achieve the objective of this invention, a polarization-dependent reflective dual-stage optical circulator is provided, comprising a first collimator, a first beam splitter cube, a first optical rotation component, a second beam splitter cube, a second optical rotation component, a third beam splitter cube, a second collimator, a third collimator, and a reflector; the first collimator, the first beam splitter cube, the first optical rotation component, the second beam splitter cube, the second optical rotation component, the third beam splitter cube, and the second collimator are arranged sequentially from left to right along a first optical path; the first beam splitter cube is provided with a first beam splitting medium film tilted 45° to the right, the second beam splitter cube is provided with a second beam splitting medium film tilted 45° to the right, and the third beam splitter cube is provided with a third beam splitting medium film tilted 45° to the left; the third collimator and the reflector are both located on the same side of the first optical path, the reflective end face of the reflector is parallel to the first optical path, the reflector faces the second beam splitting medium film, and the third collimator faces the third beam splitting medium film.

[0009] A further proposed solution is to use a reflective film as the reflector, which is deposited on the side end face of the second beam splitter cube based on the first optical path.

[0010] A further proposed solution is to use a highly reflective film as the reflector.

[0011] A further proposed solution is that the first optical rotator includes a first Faraday rotator and a first half-wave plate arranged sequentially from left to right along the first optical path.

[0012] A further proposed solution is that the first optical rotator includes a first half-wave plate and a first Faraday rotator arranged sequentially from left to right along the first optical path.

[0013] A further proposed solution is that the second optical rotator includes a second Faraday rotator and a second half-wave plate arranged sequentially from left to right along the first optical path.

[0014] A further proposed solution is that the second optical rotator includes a second half-wave plate and a second Faraday rotator arranged sequentially from left to right along the first optical path.

[0015] The beneficial effects of this invention are that it combines the characteristics of a transmissive dual-stage circulator and a reflective circulator. Two optical rotation components pass through the first optical path from the first collimator to the second collimator, thereby achieving the series connection of two isolation systems and providing a dual-stage isolation effect. Simultaneously, a reflective element is used to achieve optical path folding in the second optical path from the second collimator to the third collimator. Optical components are reused within one of the optical rotation components, also achieving a dual-stage isolation effect. Compared to existing solutions, this invention reduces product size while achieving dual-stage isolation, facilitating equipment integration and cost reduction. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of an embodiment of the reflective dual-stage optical circulator of the present invention.

[0017] Figure 2 This is a schematic diagram of the first optical path of an embodiment of the reflective dual-stage optical circulator of the present invention.

[0018] Figure 3 This is a schematic diagram of the input optical path of the second optical path in an embodiment of the reflective dual-stage optical circulator of the present invention.

[0019] Figure 4 This is a schematic diagram of the reflected optical path of the second optical path in an embodiment of the reflective dual-stage optical circulator of the present invention.

[0020] Figure 5 This is a schematic diagram of the isolated optical path of the second optical path in an embodiment of the reflective dual-stage optical circulator of the present invention.

[0021] Figure 6 This is a schematic diagram of the isolated optical path of the third optical path in an embodiment of the reflective dual-stage optical circulator of the present invention.

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0023] Reference Figure 1 The reflective bi-stage optical circulator includes a first collimator 11, a first beam splitter cube 12, a first optical rotator assembly, a second beam splitter cube 15, a second optical rotator assembly, a third beam splitter cube 18, a second collimator 19, a third collimator 20, and a reflector 21. The first optical rotator assembly includes a first Faraday optical rotator 13 and a first half-wave plate 14. The second optical rotator assembly includes a second Faraday optical rotator 16 and a second half-wave plate 17.

[0024] The first collimator 11, the first beam splitter cube 12, the first Faraday rotator 13, the first half-wave plate 14, the second beam splitter cube 15, the second Faraday rotator 16, the second half-wave plate 17, the third beam splitter cube 18, and the second collimator 19 are arranged sequentially from left to right along the first optical path.

[0025] The first beam-splitting cube 12 is provided with a first beam-splitting medium film 121 tilted to the right at 45°, the second beam-splitting cube 15 is provided with a second beam-splitting medium film 151 tilted to the right at 45°, and the third beam-splitting cube 18 is provided with a third beam-splitting medium film 181 tilted to the left at 45°.

[0026] The third collimator 20 and the reflector 21 are both located on the same side of the first optical path. The reflective end face of the reflector 21 is parallel to the first optical path, and the reflector 21 faces the second beam-splitting medium film. The reflector 21 is a reflective film, which is deposited on the side end face of the second beam-splitting cube 15 based on the first optical path. The third collimator 20 faces the third beam-splitting medium film. Of course, in addition to this embodiment, the reflector 21 can also be a high-reflectivity film, which can also achieve light reflection.

[0027] Reference Figure 2 When the first collimator 11 propagates towards the second collimator 19 along the first optical path in the forward direction, i.e., during the P1-P2 propagation, due to polarization correlation, the light output from the first collimator 11 is horizontally polarized. The horizontally polarized light enters the first beam splitter cube 12, is transmitted through the first beam splitter medium 121, and propagates along the first optical path L1. The light emitted from the first beam splitter cube 12 is horizontally polarized. After passing through the first Faraday rotator 13 and the first half-wave plate 14, the polarization state rotation angle from left to right is 0°, and the output light is still horizontally polarized. The horizontally polarized light passes through the second beam splitter cube 15, is transmitted through the second beam splitter medium 151, and the light emitted from the second beam splitter cube 15 is horizontally polarized. After passing through the second Faraday rotator 16 and the second half-wave plate 17, the polarization state rotation angle from left to right is 0°, and the output light is still horizontally polarized. The horizontally polarized light passes through the third beam splitter cube 18, is transmitted through the third beam splitter medium 181, and is input to the second collimator 19.

[0028] Reference Figure 3 When the second collimator 19 propagates towards the third collimator 20 along the second optical path in the forward direction, i.e., during the P2-P3 propagation, due to polarization dependence, the light output from the second collimator 19 is horizontally polarized light. The horizontally polarized light enters the third beam splitter cube 18, is transmitted through the third beam splitter medium film 181, and propagates along the second optical path L2. The light emitted from the third beam splitter cube 18 is horizontally polarized light. The horizontally polarized light passes through the second half-wave plate 17 and the second Faraday rotator 16, and the polarization state rotates by 90° from right to left. The output light changes to vertically polarized light. The vertically polarized light passes through the second beam splitter cube 15 and is reflected by the second beam splitter medium film 151. The light reflected from the second beam splitter cube 15 is vertically polarized light and propagates downward to the reflector 21.

[0029] Reference Figure 4The light reflected from the reflector 21 does not change its polarization state and remains vertically polarized. It propagates upward along the optical path L3 and enters the second beam splitter cube 15. The vertically polarized light is reflected by the second beam splitter film 151 and propagates to the right. The light reflected from the second beam splitter cube 15 is vertically polarized. The vertically polarized light passes through the second Faraday rotator 16 and the second half-wave plate 17. The polarization state rotates by 0° from left to right. The output light is still vertically polarized and enters the third beam splitter cube 18. The vertically polarized light is reflected by the third beam splitter film 181 and propagates downward to the third collimator 20.

[0030] Reference Figure 5 When a returning light travels from the second collimator 19 toward the first collimator 11 in the reverse direction, i.e. during P2-P1 transmission, due to polarization dependence, the light output from the second collimator 19 is horizontally polarized. The horizontally polarized light enters the third beam splitter cube 18, is transmitted through the third beam splitter dielectric film 181, and propagates along the second optical path L2. Based on the above analysis, the light propagating along the second optical path L2 will eventually reach the reflector 21 and be reflected by the reflector 21, propagating along the optical path L3. Based on the above analysis, the light propagating along L3 will eventually reach the third collimator 20 and will not reach the first collimator 11, thus forming the first stage of isolation between P2 and P1.

[0031] Since the extinction ratio of each optical element cannot be optimized, the light output from the second Faraday rotator 16 is not entirely vertically polarized light, but contains some horizontally polarized light. The horizontally polarized light is transmitted to the second beam splitter cube 15, transmitted through the second beam splitter medium 151, and propagates to the left along the optical path L4. The light emitted from the second beam splitter cube 15 is horizontally polarized light. The horizontally polarized light propagating to the left passes through the first half-wave plate 14 and the first Faraday rotator 13. The polarization state rotates by 90° from right to left, and the output light is changed to vertically polarized light. The vertically polarized light passes through the first beam splitter cube 12, is reflected by the first beam splitter medium 121, and propagates downwards out of the device optical path. The optical path L4 cannot reach the first collimator 11, thus forming the second level of isolation from P2 to P1.

[0032] Reference Figure 6When returning light travels from the third collimator 20 towards the first collimator 11 in the reverse direction (i.e., P3-P2 reverse transmission), due to polarization dependence, the output from the third collimator 20 is vertically polarized light. This vertically polarized light enters the third beam splitter cube 18, is reflected by the third beam splitter dielectric film 181, and propagates to the left. The light exiting the third beam splitter cube 18 is also vertically polarized light. This vertically polarized light passes through the second half-wave plate 17 and the second Faraday rotator 16, undergoing a 90° polarization rotation from right to left. The output light then changes to horizontally polarized light. The horizontally polarized light then passes through... The second beam splitter cube 15 is transmitted through the second beam splitter medium film 151 and propagates to the left along the optical path L5. The light emitted from the second beam splitter cube 15 is horizontally polarized. The horizontally polarized light passes through the first half-wave plate 14 and the first Faraday rotator 13, and the polarization state rotates by 90° from right to left. The polarization state of the output light changes to vertically polarized light. The vertically polarized light passes through the first beam splitter cube 12, is reflected by the first beam splitter medium film 121, and propagates downwards out of the device optical path. The optical path L5 cannot reach the second collimator 19, thus forming the first stage of isolation from P3 to P2.

[0033] Since the extinction ratio of each optical element cannot be optimized, the light output from the second Faraday rotator 16 is not entirely horizontally polarized light, but contains some vertically polarized light. The vertically polarized light passes to the left through the second beam splitting cube 15, is reflected by the second beam splitting medium film 151, and propagates downward along the optical path L6 to the reflector 21. The light reflected from the reflector 21 propagates upward along the optical path L3. Based on the above analysis, the light propagating along L3 reaches the third collimator 20, but does not reach the second collimator 19, thus forming the second level of isolation from P3 to P2.

[0034] Of course, the above embodiments are only preferred embodiments of this case. In specific applications, there can be more variations. For example, the positions of the first half-wave plate 14 and the first Faraday rotator 13 can be exchanged, or the positions of the second half-wave plate 17 and the second Faraday rotator 16 can be exchanged. They can also achieve the rotation of light polarization and achieve the purpose of this invention.

[0035] As can be seen from the above, this invention combines the characteristics of a transmissive dual-stage circulator and a reflective circulator. Two optical rotation components pass through the first optical path from the first collimator to the second collimator, thereby achieving the series connection of two isolation systems and providing a dual-stage isolation effect. Simultaneously, a reflective element is used to fold the optical path of the second optical path from the second collimator to the third collimator. Optical components are reused within one of the optical rotation components, also achieving a dual-stage isolation effect. Compared to existing solutions, this invention achieves dual-stage isolation while reducing product size, facilitating equipment integration, and reducing costs.

Claims

1. A polarization-dependent reflective two-stage optical circulator, characterized in that, It includes a first collimator, a first beam splitter cube, a first optical rotation component, a second beam splitter cube, a second optical rotation component, a third beam splitter cube, a second collimator, a third collimator, and a reflector; The first collimator, the first beam splitter cube, the first optical rotation component, the second beam splitter cube, the second optical rotation component, the third beam splitter cube, and the second collimator are arranged sequentially from left to right along the first optical path; The first beam-splitting cube is provided with a first beam-splitting medium film tilted 45° to the right, the second beam-splitting cube is provided with a second beam-splitting medium film tilted 45° to the right, and the third beam-splitting cube is provided with a third beam-splitting medium film tilted 45° to the left. The third collimator and the reflector are both located on the same side of the first optical path. The reflective end face of the reflector is parallel to the first optical path. The reflector faces the second beam-splitting medium film, and the third collimator faces the third beam-splitting medium film.

2. The reflective dual-stage optical circulator according to claim 1, characterized in that: The reflector is a reflective film, which is deposited on the side end face of the second beam splitter cube based on the first optical path.

3. The reflective two-stage optical circulator according to claim 1, characterized in that: The reflector is a high-reflectivity film.

4. The reflective dual-stage optical circulator according to any one of claims 1 to 3, characterized in that: The first optical rotator includes a first Faraday rotator and a first half-wave plate arranged sequentially from left to right along the first optical path.

5. The reflective dual-stage optical circulator according to any one of claims 1 to 3, characterized in that: The first optical rotator includes a first half-wave plate and a first Faraday rotator arranged sequentially from left to right along the first optical path.

6. The reflective two-stage optical circulator according to any one of claims 1 to 3, characterized in that: The second optical rotator includes a second Faraday rotator and a second half-wave plate arranged sequentially from left to right along the first optical path.

7. The reflective two-stage optical circulator according to any one of claims 1 to 3, characterized in that: The second optical rotator includes a second half-wave plate and a second Faraday rotator arranged sequentially from left to right along the first optical path.

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