Polarization-dependent reflective two-stage optical circulator

Abstract

The invention provides a polarization-dependent reflective two-stage optical circulator which comprises a first collimator, a first beam splitting cube, a first optical rotation assembly, a second beam splitting cube, a third beam splitting cube of the second optical rotation assembly and a second collimator which are arranged along a first optical path, and the three beam splitting cubes are respectively provided with a light splitting dielectric film. According to the scheme, the characteristics of a transmission-type two-stage circulator and a reflection-type circulator are combined, two optical rotation assemblies pass through a first optical path from the first collimator to the second collimator, then series connection of two isolation systems is achieved, and the effect of two-stage isolation is achieved; meanwhile, light path folding of second light paths from the second collimator to the third collimator is achieved through the reflecting part, optical part multiplexing is carried out in one optical rotation assembly, the double-stage isolation effect is achieved, the double-stage isolation effect is achieved, meanwhile, the product size is reduced, equipment integration is facilitated, and cost is also reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of optical circulators, and in particular to a polarization-dependent reflective double-stage optical circulator. Background Art

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

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

[0004] According to the design of the fiber laser system, if there is strong reverse light in the system, it is easy to cause the fiber laser system to be unstable, performance degradation, and even burn the entire system. Therefore, it is necessary to add protective devices with unidirectional conduction and reverse isolation to the fiber laser system. Circulators are widely used in some laser systems because they have both loop function and reverse blocking function.

[0005] There are two main types of circulators in the prior art. One is a transmission-type two-stage circulator, which generally adopts a linear design and achieves a double-stage isolation effect through two isolation systems connected in series. However, the transmission-type two-stage circulator has the following disadvantages: the double-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 the double-stage isolation effect is required at the same time, three isolation systems are required, connected in series in pairs. The overall size of the device is large and the cost is high.

[0006] The other is a reflective circulator, which uses high-reflectivity coatings to fold the optical path, multiplex optical components such as Faraday rotators, and achieve a double-stage isolation effect with only one isolation system. However, the optical path design of this circulator can only satisfy that one path, such as the optical path from port 1 to port 2, passes through the folded optical path, thus achieving a double-stage isolation effect, while the other path, such as the optical path from port 2 to port 3, does not pass through the folded optical path and only has a single-stage isolation effect. Summary of the invention

[0007] The object of the present invention is to provide a polarization-dependent reflective two-stage optical circulator.

[0008] In order to achieve the purpose of the present invention, the present invention provides a polarization-dependent reflective two-stage optical circulator, comprising a first collimator, a first beam splitting cube, a first optical rotation component, a second beam splitting cube, a second optical rotation component, a third beam splitting cube, a second collimator, a third collimator and a reflector; the first collimator, the first beam splitting cube, the first optical rotation component, the second beam splitting cube, the second optical rotation component, the third beam splitting cube and the second collimator are arranged in sequence from left to right along a first optical path; the first beam splitting cube is provided with a first optical splitting dielectric film inclined at 45° to the right, the second beam splitting cube is provided with a second optical splitting dielectric film inclined at 45° to the right, and the third beam splitting cube is provided with a third optical splitting dielectric film inclined at 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 optical splitting dielectric film, and the third collimator faces the third optical splitting dielectric film.

[0009] A further solution is that the reflective element is a reflective film, and the reflective film is plated on the side end face of the second beam splitting cube based on the first optical path.

[0010] A further solution is that the reflective element is a high-reflective sheet.

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

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

[0013] A further solution is that the second optical rotation component includes a second Faraday optical rotation element and a second half-wave plate which are arranged in sequence from left to right along the first optical path.

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

[0015] The beneficial effect of the present invention is that, in this case, the characteristics of the transmissive two-stage circulator and the reflective circulator are combined, and the first optical path from the first collimator to the second collimator passes through two optical rotation components, and then the two isolation systems are connected in series, which achieves the effect of double-stage isolation. At the same time, the reflector is used to realize the optical path folding of the second optical path from the second collimator to the third collimator, and the optical components are multiplexed in one of the optical rotation components, which also achieves the effect of double-stage isolation. Compared with the prior art solutions, while achieving the effect of double-stage isolation, the present case also reduces the product volume, is conducive to the integration of equipment, and is also conducive to reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic structural diagram of an embodiment of a reflective two-stage optical circulator of the present invention.

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

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

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

[0020] Figure 5 It is a schematic diagram of the isolation optical path of the second optical path in the embodiment of the reflective double-stage optical circulator of the present invention.

[0021] Figure 6 It is a schematic diagram of the isolation optical path of the third optical path in the embodiment of the reflective two-stage optical circulator of the present invention.

[0022] The present invention is further described below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

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

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

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

[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, the reflector 21 faces the second beam splitting medium film, the reflector 21 is a reflective film, the reflective film is plated on the side end face of the second beam splitting cube 15 based on the first optical path, and 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 reflective film, which can also achieve light reflection.

[0027] Reference Figure 2 When the first collimator 11 transmits forward along the first optical path toward the second collimator 19, that is, during P1-P2 transmission, due to polarization correlation, the light output from the first collimator 11 is horizontally polarized light, the horizontally polarized light enters the first beam splitter cube 12, is transmitted through the first beam splitter dielectric film 121, and is transmitted along the first optical path L1. The light emitted from the first beam splitter cube 12 is horizontally polarized light, passes through the first Faraday rotator 13 and the first half-wave plate 14, and the polarization state is rotated by an angle of 0° from left to right during transmission, and the output light is still horizontally polarized light. The horizontally polarized light passes through the second beam splitter cube 15, and is transmitted through the second beam splitter dielectric film 151. The light emitted from the second beam splitter cube 15 is horizontally polarized light, passes through the second Faraday rotator 16 and the second half-wave plate 17, and the polarization state is rotated by an angle of 0° from left to right during transmission, and the output light is still horizontally polarized light. The horizontally polarized light passes through the third beam splitter cube 18, is transmitted through the third beam splitter dielectric film 181, and is input to the second collimator 19.

[0028] Reference Figure 3 When the second collimator 19 transmits forward along the second optical path toward the third collimator 20, that is, during P2-P3 transmission, due to polarization correlation, the light output from the second collimator 19 is horizontally polarized light, and the horizontally polarized light enters the third beam splitter cube 18, is transmitted through the third beam splitter dielectric film 181, and is transmitted 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 is rotated by 90° from right to left. The output light is changed to vertically polarized light. The vertically polarized light passes through the second beam splitter cube 15, and is reflected from the second beam splitter dielectric film 151. The light reflected from the second beam splitter cube 15 is vertically polarized light, which is transmitted downward to reach the reflector 21.

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

[0030] Reference Figure 5 When the return light is transmitted from the second collimator 19 to the first collimator 11 in the reverse direction, that is, during P2-P1 transmission, due to polarization correlation, 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 splitting medium film 181, and is transmitted along the second optical path L2. According to the above analysis, the light transmitted along the second optical path L2 will eventually reach the reflector 21, and be reflected from the reflector 21, and be transmitted along the optical path L3. According to the above analysis, the light transmitted along L3 finally reaches the third collimator 20, and will not reach the first collimator 11, which is the first level isolation of P2-P1.

[0031] Since the extinction ratio of each optical element cannot be optimized, the light output from the second Faraday rotator 16 is not completely vertically polarized light, but contains part of horizontally polarized light. The horizontally polarized light is transmitted to the second beam splitter cube 15, transmitted through the second beam splitter dielectric film 151, and transmitted 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 transmitted to the left passes through the first half-wave plate 14 and the first Faraday rotator 13. The polarization state is rotated 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 at the first beam splitter dielectric film 121, and is transmitted downward to leave the device optical path. The optical path L4 cannot reach the first collimator 11, which is the second level isolation from P2 to P1.

[0032] Reference Figure 6When the return light is transmitted from the third collimator 20 to the first collimator 11 in the reverse direction, that is, when P3-P2 is transmitted in the reverse direction, due to polarization correlation, the output from the third collimator 20 is vertically polarized light, and the vertically polarized light enters the third beam splitter cube 18, is reflected by the third beam splitter dielectric film 181, and is transmitted to the left. The light emitted from the third beam splitter cube 18 is vertically polarized light, and the vertically polarized light passes through the second half-wave plate 17 and the second Faraday rotator 16, and the transmission polarization state is rotated by 90° from right to left, and the output light is changed to horizontally polarized light. The horizontally polarized light passes through The second beam splitter cube 15 is transmitted through the second beam splitter dielectric film 151 and is transmitted to the left along the optical path L5. The light emitted from the second beam splitter cube 15 is horizontally polarized light. The horizontally polarized light passes through the first half-wave plate 14 and the first Faraday rotator 13, and the polarization state is rotated by 90° from right to left. The polarization state of 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 dielectric film 121, and is transmitted downward to leave the device optical path. The optical path L5 cannot reach the second collimator 19, which is the first level 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 completely horizontally polarized light, but contains some vertically polarized light. The vertically polarized light passes through the second beam splitting cube 15 to the left, is reflected by the second beam splitting medium film 151, and is transmitted downward along the optical path L6 to reach the reflector 21. The light reflected from the reflector 21 is transmitted upward along the optical path L3. According to the above analysis, the light transmitted along L3 reaches the third collimator 20, but does not reach the second collimator 19, which is the second level isolation from P3 to P2.

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

[0035] As can be seen from the above, this case combines the characteristics of a transmissive two-stage circulator and a reflective circulator. The first optical path from the first collimator to the second collimator passes through two optical rotation components, and then the two isolation systems are connected in series, which achieves a double-stage isolation effect. At the same time, the reflector is used to realize the optical path folding of the second optical path from the second collimator to the third collimator, and optical components are reused in one of the optical rotation components, which also achieves the double-stage isolation effect. Compared with the prior art solutions, while achieving the effect of double-stage isolation, this case also reduces the product volume, is conducive to the integration of equipment, and is also conducive to reducing costs.

Claims

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

2. The reflective double-stage optical circulator according to claim 1, characterized in that: The reflective element is a reflective film, and the reflective film is plated on a side end surface of the second beam splitting cube based on the first optical path.

3. The reflective double-stage optical circulator according to claim 1, characterized in that: The reflective element is a high reflective sheet.

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

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

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

7. The reflective double-stage optical circulator according to any one of claims 1 to 3, characterized in that: The second optical rotation component includes a second half-wave plate and a second Faraday optical rotation element which are arranged in sequence from left to right along the first optical path.

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