Reflective optical circulator and method of making the same

Abstract

The application provides a reflective optical circulator and a manufacturing method thereof. The optical circulator comprises a collimator array, one end of the collimator array is provided with a first birefringent crystal, the first birefringent crystal is provided with a half-wave plate group away from one end of the collimator array, the half-wave plate group is provided with a rotating device away from one end of the first birefringent crystal, and the rotating device is provided with a second birefringent crystal away from one end of the half-wave plate group; the second birefringent crystal is provided with an achromatic wave plate group away from one end of the rotating device, a first half-wave plate is arranged close to the second birefringent crystal, and a quarter-wave plate is arranged away from the second birefringent crystal; the optical axis of the first half-wave plate is 75 degrees and the optical axis of the quarter-wave plate is 15 degrees based on the bottom surface of the reflective optical circulator; and a reflecting device is arranged away from one end of the achromatic wave plate group. The application also provides a manufacturing method of the optical circulator. The application can effectively reduce the return loss of the optical circulator.

Description

Technical Field

[0001] The present invention relates to the technical field of optical communication devices, in particular to a reflective optical circulator and a method for manufacturing the optical circulator. Background Art

[0002] As fiber-optic communication systems evolve toward higher speeds and higher-density integration, miniaturization and high performance of optical components have become key requirements. Traditional transmissive optical circulators utilize a straight-through optical path design. While capable of directional signal transmission, these circulators are bulky and require complex optical component stacking, making them difficult to package in compact optical modules. Consequently, reflective optical circulators have become widely used in fiber-optic communication systems.

[0003] Reflective optical circulators feature a unique folded optical path structure. By replacing some optical components with reflective end faces, they significantly reduce their size and polarization-dependent loss, making them the most commonly used optical circulators in high-speed coherent communications and silicon photonics integration. The core operating principle of reflective optical circulators relies on the combination of a Faraday rotator and a quarter-wave plate, achieving nonreciprocal transmission through polarization state manipulation.

[0004] For example, publications CN116148980A and CN119414524A disclose two reflective optical circulators. However, existing reflective optical circulators often face a bottleneck problem of deteriorating return loss over a wide wavelength range (such as the O band and the C+L band). This bottleneck is due to the non-ideal optical rotation device of the Faraday rotator and the dispersion phase delay of the quarter-wave plate. This reduces the conversion efficiency of existing reflective optical circulators for the desired polarization and generates residual linear polarization components. These residual linear polarization components interfere with each other multiple times, forming high-order echoes directed toward the input port.

[0005] Because the Faraday rotator and quarter-wave plate used in existing reflective optical circulators only rotate a single wavelength of light, incomplete rotation produces residual linear polarization components. These residual linear polarization components interfere with each other, causing the return loss curve of the reflective optical circulator to fluctuate with wavelength. This fluctuation leads to unstable return loss of the reflective optical circulator. In the wavelength range of 1260 nm to 1360 nm, the return loss of the reflective optical circulator is generally above -50 decibels, affecting the overall performance of the reflective optical circulator. Summary of the Invention

[0006] A first object of the present invention is to provide a reflective optical circulator with relatively stable return loss.

[0007] A second object of the present invention is to provide a method for manufacturing the above-mentioned reflective optical circulator.

[0008] To achieve the above-mentioned first objective, the present invention provides a reflective optical circulator comprising a collimator array, wherein a first birefringent crystal is disposed at one end of the collimator array, a half-wave plate group is disposed at an end of the first birefringent crystal away from the collimator array, a rotating device is disposed at an end of the half-wave plate group away from the first birefringent crystal, and a second birefringent crystal is disposed at an end of the rotating device away from the half-wave plate group; an achromatic wave plate group is disposed at an end of the second birefringent crystal away from the rotating device, the achromatic wave plate group comprising a first half-wave plate and a quarter-wave plate arranged adjacent to each other, the first half-wave plate being disposed proximate to the second birefringent crystal, and the quarter-wave plate being disposed away from the second birefringent crystal; with respect to the bottom surface of the reflective optical circulator as a reference, the optical axis of the first half-wave plate is 75°, the optical axis of the quarter-wave plate is 15°, the first half-wave plate has a first preset thickness, and the quarter-wave plate has a second preset thickness; and a reflecting device is disposed at an end of the achromatic wave plate group away from the second birefringent crystal.

[0009] As can be seen from the above scheme, the reflective optical circulator of the present invention is equipped with an achromatic wave plate assembly. Compared to using a quarter-wave plate alone, the achromatic wave plate assembly can provide optical rotation over a wider wavelength band. Therefore, the achromatic wave plate assembly of the present invention can rotate the polarization state of light beams within a wider wavelength band, thereby reducing the residual linear polarization component at the edge waves of the band, thereby reducing the mutual interference of light beams at the edge wavebands. As a result, the present invention can effectively prevent the problem of unstable return loss caused by the mutual interference of residual linear polarization components.

[0010] A preferred solution is that the first half-wave plate and the quarter-wave plate are arranged parallel to each other, and the first half-wave plate and the quarter-wave plate are glued together.

[0011] It can be seen that fixing the first half-wave plate and the quarter-wave plate by gluing can reduce the volume of the achromatic wave plate group, which is conducive to the miniaturization of the reflective optical circulator.

[0012] A further solution is that the achromatic wave plate group is attached to the end face of the second birefringent crystal away from the rotating device.

[0013] It can be seen from this that the distance between the achromatic wave plate set and the second birefringent crystal is very small, which can further reduce the volume of the reflective optical circulator.

[0014] A further solution is that the half-wave plate set includes a second half-wave plate and a third half-wave plate arranged adjacent to each other, and the second half-wave plate and the third half-wave plate are respectively arranged on two optical paths of the first birefringent crystal. Preferably, the optical axes of the second half-wave plate and the third half-wave plate are both 22.5°.

[0015] It can be seen that the polarization states of the two light beams with opposite polarization states emitted from the first birefringent crystal can be rotated to the same polarization state through the half-wave plate group, which is beneficial to the polarization state conversion of linear polarized light in the subsequent stage.

[0016] A further solution is that the optical axis of the first birefringent crystal and the optical axis of the second birefringent crystal are respectively on two mutually orthogonal planes.

[0017] It can be seen that by properly setting the optical axis of the first birefringent crystal and the optical axis of the second birefringent crystal, the light beam can be split according to the polarization state, and the reflected light beams can be combined.

[0018] A further solution is that the rotating device is a Faraday rotator, and the operating wavelength of the Faraday rotator is the central wavelength of the reflective optical circulator.

[0019] A further solution is that the apertures of the light holes of the first birefringent crystal, the rotating device, the second birefringent crystal and the achromatic wave plate group are equal.

[0020] It can be seen that, since the apertures of the light holes of the multiple optical elements are equal, the overall aperture of the reflective optical circulator is the same, which is beneficial to the packaging of the reflective optical circulator.

[0021] To achieve the above-mentioned second purpose, the manufacturing method of the reflective optical circulator provided by the present invention includes: gluing a first half-wave plate and a quarter-wave plate together to form an achromatic wave plate group, the optical axis of the first half-wave plate is 75°, and the optical axis of the quarter-wave plate is 15°; arranging a half-wave plate group at one end of a first birefringent crystal, and arranging a rotating device at the end of the half-wave plate group away from the first birefringent crystal, and arranging a second birefringent crystal at the end of the rotating device away from the half-wave plate group, pasting the achromatic wave plate group to the end face of the second birefringent crystal rotating device, so that the first half-wave plate is arranged close to the second birefringent crystal, and the quarter-wave plate is arranged away from the second birefringent crystal; arranging a reflecting device at the end of the achromatic wave plate group away from the second birefringent crystal, and arranging a collimator array at the end of the first birefringent crystal away from the half-wave plate group.

[0022] It can be seen from the above scheme that by arranging an achromatic wave plate group at one end of the second birefringent crystal, the achromatic wave plate group consists of a first half-wave plate and a quarter-wave plate. Based on the principle that the first half-wave plate rotates the polarization state of the light beam, the linearly polarized light emitted from the second birefringent crystal will become circularly polarized light after passing through the achromatic wave plate group, and the polarization state of the circularly polarized light will not change after passing through the reflector. The reflected light beam will be converted from circularly polarized light to linearly polarized light again after passing through the achromatic wave plate group again, but the polarization state of the light beam at this time is orthogonal to the polarization state when it first emerges from the second birefringent crystal, that is, the polarization state is different. Therefore, the residual linear polarization component generated by incomplete optical rotation has different polarization directions when passing through the second birefringent crystal twice, and thus will not form interference at the incident port. Therefore, the problem of unstable return loss caused by mutual interference of the residual linear polarization components can be effectively suppressed.

[0023] A preferred solution is that when a half-wave plate group is set at one end of the first birefringent crystal, the second half-wave plate and the third half-wave plate are set at one end of the first birefringent crystal, and the second half-wave plate and the third half-wave plate are respectively set on two optical paths of the first birefringent crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 1 is a structural diagram of an embodiment of a reflective optical circulator according to the present invention.

[0025] Figure 2 This is a light path diagram of the reflective optical circulator embodiment of the present invention from a first viewing angle.

[0026] Figure 3 This is a light path diagram of the reflective optical circulator embodiment of the present invention from a second viewing angle.

[0027] Figure 4 1 is a structural diagram of an achromatic wave plate assembly in an embodiment of a reflective optical circulator according to the present invention.

[0028] Figure 5 FIG. 1 is a schematic diagram of the optical axis of the achromatic wave plate assembly of the reflective optical circulator embodiment of the present invention. FIG.

[0029] Figure 6 FIG. 4 is a return loss curve diagram of an embodiment of a reflective optical circulator of the present invention.

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0031] The reflective optical circulator of the present application is applied in an optical fiber communication network for realizing the transmission of optical beams along a specific optical path. In order to avoid the problem of the deterioration of the return loss of the reflective optical circulator in a wide wavelength range, the present application adjusts the quarter-wave plate and uses the structure of an achromatic wave plate set to suppress the problem of the instability of the return loss caused by the mutual interference of the residual linear polarization components of the optical rotation incompleteness.

[0032] Embodiment of the reflective optical circulator

[0033] Referring to Figure 1 The reflective optical circulator of the present embodiment has a collimator array 10 which includes a plurality of collimators, for example, a first collimator 11, a second collimator 12 and a third collimator 13, which are arranged in sequence along the x-axis direction. Preferably, the first collimator 11, the second collimator 12 and the third collimator 13 are parallel to each other. A first birefringent crystal 21 is arranged at one end of the collimator array 10, and a half-wave plate set 22 is arranged at the end of the first birefringent crystal 21 away from the collimator array 10, referring to Figure 3 The half-wave plate set 22 has two half-wave plates, namely a second half-wave plate 25 and a third half-wave plate 26. The second half-wave plate 25 and the third half-wave plate 26 are respectively located on two optical paths of the first birefringent crystal 21. Preferably, the second half-wave plate 25 and the third half-wave plate 26 are arranged adjacent along the y-axis, and the aperture of the light transmission hole of the second half-wave plate 25 is half of the aperture of the light transmission hole of the first birefringent crystal 21, and the aperture of the light transmission hole of the third half-wave plate 26 is also half of the aperture of the light transmission hole of the first birefringent crystal 21. In addition, with the bottom surface of the reflective optical circulator as the reference, i.e. with the xOz plane as the reference, the optical axis of the second half-wave plate 25 is 22.5°, and the optical axis of the third half-wave plate 26 is also 22.5°, but the directions of the optical axes of the second half-wave plate 25 and the third half-wave plate 26 are respectively along two different directions, for example, the optical axis of the second half-wave plate 25 is directed towards the positive direction of the y-axis, and the optical axis of the third half-wave plate 26 is directed towards the negative direction of the y-axis.

[0034] A rotating device is arranged at the end of the half-wave plate set 22 away from the first birefringent crystal 21, and the rotating device of the present embodiment is a Faraday rotator 31. Preferably, a magnet is arranged around the periphery of the Faraday rotator 31, and the Faraday rotator 31 can rotate the polarization state of the linear polarization state by 45° under a saturated magnetic field. In addition, the operating wavelength of the Faraday rotator 31 is the center wavelength of the reflective optical circulator. A second birefringent crystal 32 is arranged at the end of the Faraday rotator 31 away from the half-wave plate set 22, and the optical axes of the first birefringent crystal 21 and the second birefringent crystal 32 are respectively in two mutually orthogonal planes.

[0035] An achromatic wave plate set is provided at the end of the second birefringent crystal 32 away from the rotating device. The achromatic wave plate set of this embodiment is composed of a first half-wave plate 33 and a quarter-wave plate 34 arranged adjacent to each other, wherein the first half-wave plate 33 is provided close to the second birefringent crystal 32, and the quarter-wave plate 34 is provided away from the second birefringent crystal 32. With respect to the bottom surface of the reflective optical circulator, the optical axis of the first half-wave plate 33 is 75°, and the optical axis of the quarter-wave plate 34 is 15°. Figure 4 and Figure 5 As shown, in Figure 5 In the figure, arrow A1 is the optical axis of the first half-wave plate 33, and arrow A2 is the optical axis of the quarter-wave plate 34. In addition, the first half-wave plate 33 and the quarter-wave plate 34 are glued together. In addition, the apertures of the light holes of the first half-wave plate 33 and the quarter-wave plate 34 are equal. Furthermore, the achromatic wave plate group is attached to the end face of the second birefringent crystal 32, that is, one surface of the first half-wave plate 33 is attached to the end face of the second birefringent crystal 32. In addition, the thickness of the first half-wave plate 33 is a first preset thickness, for example, the thickness of the first half-wave plate 33 is determined according to the center wavelength of the working light beam of the reflective optical circulator. In addition, the thickness of the quarter-wave plate 34 is a second preset thickness, which is also determined according to the center wavelength of the working light beam of the reflective optical circulator, thereby ensuring that the achromatic wave plate group can accurately rotate the light beam of a specific wavelength and can effectively avoid the problem of incomplete rotation of the linear polarization component.

[0036] A reflective element is disposed at the end of the achromatic wave plate assembly away from the second birefringent crystal 32. In this embodiment, the reflective element is a reflector 35, with its surface facing the achromatic wave plate assembly. In this embodiment, the apertures of the first birefringent crystal 21, the Faraday rotator 31, the second birefringent crystal 32, the achromatic wave plate assembly, and the reflector 35 are all equal. This allows the reflective optical circulator to be packaged within a single sleeve, enabling miniaturization and integrated assembly of the reflective optical circulator.

[0037] The following combination Figure 2 and Figure 3 The optical path of a reflective optical circulator is described below. The light beam emitted from the first collimator 11 is used as an example. After the light beam L11 emitted from the first collimator 11 enters the first birefringent crystal 21, it is split into two beams, namely, light beams L21 and L31. One of the light beams L21 and L31 is normal light, and the other is abnormal light. The two light beams L21 and L31 are transmitted in different directions, as shown in Figure 2. Figure 3 As shown, the light beams L21 and L31 are laterally translated along the y-axis, but the transmission optical paths of the two light beams L21 and L31 in the x-axis direction are overlapped.

[0038] When light beams L21 and L31 emerge from the first birefringent crystal 21, they pass through the second half-wave plate 25 and the third half-wave plate 26, respectively. Since the optical axes of the second and third half-wave plates 25 and 26 are in opposite directions, the polarization directions of the light beams L21 and L31 after passing through the half-wave plate set are the same. Next, the light beams pass through the Faraday rotator 31. When a saturating magnetic field is applied to the Faraday rotator 31, the polarization directions of the two light beams are simultaneously rotated by 45°, and the two light beams are incident on the second birefringent crystal 32 as normal light. Figure 3 As shown, after entering the second birefringent crystal 32, two light beams L22 and L23 are formed respectively. Both light beams are transmitted along the path of normal light in the second birefringent crystal 32, that is, Figure 2 As shown in L12, therefore, the light beams L22 and L23 will not be deflected, that is, they will not be emitted and offset in the x-axis direction.

[0039] The light beams are then incident on the achromatic wave plate set consisting of the first half-wave plate 33 and the quarter-wave plate 34. Since the first half-wave plate 33 is close to the second birefringent crystal 32, the light beams first pass through the first half-wave plate 33 and then through the quarter-wave plate 34. After passing through the first half-wave plate 33, the polarization direction of the light beams will rotate, and after passing through the quarter-wave plate 34, the polarization state will rotate again. The two light beams are then incident on the reflector 35. Since the reflective surface of the reflector 35 is perpendicular to the incident direction of the light beams, the light beams will return along the original path. Since the reflector 35 does not change the polarization direction of the light beams, the polarization direction of the light beams reflected by the reflector 35 is the same as the polarization direction at the time of incidence.

[0040] After being reflected, the light beams L23 and L33 pass through the achromatic wave plate set again. At this time, the light beams first pass through the quarter-wave plate 34 and then pass through the first half-wave plate 33. When the light beams L23 and L33 pass through the quarter-wave plate 34, they are rotated again. When the light beams pass through the first half-wave plate 33, the polarization states of the light beams are deflected again. After the light beams pass through the first half-wave plate 33 and the quarter-wave plate 34 twice, the polarization directions of the light beams are rotated by a total of 90°, thereby achieving the polarization direction of the light beams after passing through the achromatic wave plate set for the second time being orthogonal to the polarization direction when the light beams first emerge from the second birefringent crystal 32. Specifically, after light beam L22 is reflected by the reflector 35, it forms light beam L23. The polarization direction of light beam L22 when it emerges from the second birefringent crystal 32 is orthogonal to the polarization direction of light beam L23 when it enters the second birefringent crystal 32, that is, the polarization directions of light beams L22 and L23 are different.

[0041] Compared with the light beam L22, the polarization direction of the light beam L23 is changed. Therefore, the light beam L23 will be transmitted along the direction of the abnormal light in the second birefringent crystal 32, such as Figure 2As shown, the light beam L33 is transmitted along the path of L13, that is, it is laterally offset in the x-axis direction compared to L12, and is offset toward the second collimator 12. Similarly, the light beam L33 is also transmitted along the direction of the abnormal light.

[0042] Next, light beams L23 and L33 pass through the Faraday rotator 31 and the half-wave plate assembly 22. Light beam L23 passes through the second half-wave plate 25, and light beam L33 passes through the third half-wave plate 26. Light beams L23 and L33 are incident on the first birefringent crystal 21, forming light beams L24 and L34, respectively. These light beams are then combined within the first birefringent crystal 21 to form light beam L14. Finally, light beam L14 emerges from the second collimator 12. It can be seen that the light beam emerging from the first collimator 11 will emerge from the second collimator 12. Similarly, the light beam incident from the second collimator 12 will emerge from the third collimator 13. In this way, unidirectional transmission of the optical path is achieved, thereby fulfilling the function of an optical circulator.

[0043] Since a quarter-wave plate can only delay a light beam of a specific wavelength, if the quarter-wave plate is designed for a wavelength of 1310nm, then the thickness of the quarter-wave plate must be 0.038mm. Only when a light beam with a wavelength of 1310nm passes through it will a phase delay of π / 2 be generated. For light beams of other wavelengths, such as 1260nm or 1360nm, the delay generated after entering a quarter-wave plate with a thickness of 0.038mm is not π / 2. Therefore, the optical rotation effect of a quarter-wave plate is only for light beams of a specific wavelength. However, since the light beam incident on the optical circulator often does not only contain the central wavelength, for example, the central wavelength of the incident light beam is 1310nm, but it often contains beam components of other wavelengths. The quarter-wave plate cannot accurately delay these beam components, resulting in incomplete optical rotation.

[0044] Achromatic wave plates, on the other hand, have an optical rotation effect over a wider wavelength range. For example, they can rotate light beams in the wavelength range of 1260nm to 1360nm, and the angle of rotation remains the same for all beams within this wavelength range. Thus, if the center wavelength of a beam is 1310nm, then light beams at the edge bands of the beam, such as those with wavelengths of 1260nm or 1360nm, will also be fully rotated. Therefore, by providing an achromatic wave plate set, the problem of incomplete polarization rotation of light beams at the edge bands can be reduced, thereby reducing the residual linear polarization component at the edge bands, thereby reducing interference between light beams at the edge bands and suppressing return loss.

[0045] The reflective optical circulator of this embodiment can effectively suppress the problem of unstable return loss caused by the interference of residual linear polarization components generated by the incomplete rotation of linear polarization light by the Faraday rotator 31 or the quarter-wave plate 34. Figure 6 In conventional optical circulators fabricated using quarter-wave plates, the return loss of reflective optical circulators is generally above -50 decibels within the wavelength range of 1260 to 1360 nanometers. However, a wide-spectrum scan of the return loss of the reflective optical circulator of this embodiment reveals that the return loss is consistently below the -50 decibel benchmark requirement, from 1260 to 1360 nanometers. Compared to conventional reflective optical circulators, this embodiment exhibits significantly lower return loss across a wide spectrum, thereby improving the overall performance of the reflective optical circulator.

[0046] Of course, the present invention is not limited to the O band with a wavelength range of 1260 nm to 1360 nm. For light beams in other wavelength ranges, the achromatic wave plate provided in this embodiment can also be used to reduce the return loss of the reflective optical circulator.

[0047] Embodiment of the manufacturing method of reflective optical circulator:

[0048] When making the above-mentioned reflective optical ring device, first make an achromatic wave plate set. Specifically, first prepare a first half-wave plate and a quarter-wave plate, align the first half-wave plate and the quarter-wave plate according to the preset optical axis direction, and then glue the first half-wave plate and the quarter-wave plate together.

[0049] Then, two birefringent crystals are prepared as the first and second birefringent crystals, and two half-wave plates are prepared as the second and third half-wave plates, respectively. The second and third half-wave plates have the same shape, except for different optical axes. Therefore, a large half-wave plate can be cut and the two half-wave plates are arranged according to a specific optical axis position to form a half-wave plate set. The second and third half-wave plates are placed at one end of the first birefringent crystal, respectively. A Faraday rotator is placed at one end of the half-wave plate set, and the second birefringent crystal is placed at one end of the Faraday rotator.

[0050] Next, the pre-prepared achromatic wave plate assembly is bonded to one end of the second birefringent crystal, with the first half-wave plate attached to the end face of the second birefringent crystal. Finally, the reflector is placed on the side of the achromatic wave plate assembly near the quarter-wave plate, and the collimator array is placed on one end of the first birefringent crystal. Of course, if the reflective optical circulator needs to be placed in a sleeve, the above optical components need to be placed in the appropriate position within the sleeve to complete the packaging of the reflective optical circulator.

[0051] Since the reflective optical circulator of the present invention is provided with an achromatic wave plate group, the achromatic wave plate group can rotate the light beam within a wider wavelength range, thereby avoiding the residual linear polarization component generated by the incomplete optical rotation of the light beam at the edge of the band. Therefore, the problem of unstable return loss caused by the interference of the residual linear polarization components can be effectively suppressed.

[0052] Finally, it should be emphasized that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Reflective optical circulator, including: A collimator array, wherein a first birefringent crystal is provided at one end of the collimator array, a half-wave plate group is provided at an end of the first birefringent crystal away from the collimator array, a rotating device is provided at an end of the half-wave plate group away from the first birefringent crystal, and a second birefringent crystal is provided at an end of the rotating device away from the half-wave plate group; Its characteristics are: An achromatic wave plate group is provided at one end of the second birefringent crystal away from the rotating device, the achromatic wave plate group consisting of a first half-wave plate and a quarter-wave plate arranged adjacent to each other, the first half-wave plate being arranged close to the second birefringent crystal, and the quarter-wave plate being arranged away from the second birefringent crystal; with the bottom surface of the reflective optical circulator as a reference, the optical axis of the first half-wave plate is 75°, the optical axis of the quarter-wave plate is 15°, the first half-wave plate has a first preset thickness, and the quarter-wave plate has a second preset thickness; A reflective device is provided at one end of the achromatic wave plate assembly away from the second birefringent crystal; The first half-wave plate and the quarter-wave plate are arranged parallel to each other, and the first half-wave plate and the quarter-wave plate are glued together; The achromatic wave plate set is attached to the end face of the second birefringent crystal away from the rotating device; The half-wave plate group includes a second half-wave plate and a third half-wave plate that are adjacent to each other. The second half-wave plate and the third half-wave plate are respectively arranged on two optical paths of the first birefringent crystal.

2. The reflective optical circulator according to claim 1, wherein: The optical axes of the second half-wave plate and the third half-wave plate are both 22.5°.

3. The reflective optical circulator according to claim 1 or 2, wherein: The optical axis of the first birefringent crystal and the optical axis of the second birefringent crystal are respectively on two mutually orthogonal planes.

4. The reflective optical circulator according to claim 1 or 2, wherein: The rotating device is a Faraday rotator, and the operating wavelength of the Faraday rotator is the central wavelength of the reflective optical circulator.

5. The reflective optical circulator according to claim 1 or 2, wherein: The apertures of the light holes of the first birefringent crystal, the rotating device, the second birefringent crystal and the achromatic wave plate group are equal.

6. A method for manufacturing a reflective optical circulator, for manufacturing the reflective optical circulator according to any one of claims 1 to 5, characterized in that: include: gluing a first half-wave plate and a quarter-wave plate together to form an achromatic wave plate set, wherein the optical axis of the first half-wave plate is 75° and the optical axis of the quarter-wave plate is 15°; A half-wave plate group is provided at one end of a first birefringent crystal, and a rotating device is provided at an end of the half-wave plate group away from the first birefringent crystal, and a second birefringent crystal is provided at an end of the rotating device away from the half-wave plate group. The achromatic wave plate group is adhered to an end face of the second birefringent crystal away from the rotating device, so that the first half-wave plate is provided close to the second birefringent crystal and the quarter-wave plate is provided away from the second birefringent crystal. A reflector is provided at one end of the achromatic wave plate group away from the second birefringent crystal, and a collimator array is provided at one end of the first birefringent crystal away from the half-wave plate group; When a half-wave plate group is set at one end of the first birefringent crystal, the second half-wave plate and the third half-wave plate are set at one end of the first birefringent crystal, and the second half-wave plate and the third half-wave plate are respectively set on two optical paths of the first birefringent crystal.

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