Optical filter and optical communication equipment

Abstract

The utility model relates to the technical field of optical communication, in particular to an optical filter and optical communication equipment. The optical filter comprises a first polarization output assembly used for converting input light input from a first side into single polarized light and outputting the single polarized light, and the single polarized light has a target polarization direction; the polarizing beam splitter is located on the second side of the first polarization output assembly, the second side is opposite to the first side, and the polarizing beam splitter can transmit light in the target polarization direction and reflect light in other polarization directions; and the two comb filters are respectively positioned in two mutually vertical light emitting directions of the polarizing beam splitter, the filtering wavelength of each comb filter is adjustable, and each comb filter comprises a G-T resonant cavity. The optical filter provided by the utility model is simple in optical path and compact in structure, facilitates reduction of optical loss in an optical system, and is also easy to maintain and adjust.

Description

Technical Field

[0001] This utility model relates to the field of optical communication technology, and in particular to an optical filter and an optical communication device. Background Technology

[0002] Optical filters are among the most commonly used optical devices in the field of optics. Currently, commonly used optical filters are generally based on coating, optical interference, and grating beam splitting systems. Among them, standard interferometric filters based on FP (Fabry-Perot) interferometer cavities are very common and have very important applications in optics.

[0003] In a FP interferometer cavity, light undergoes multiple reflections within the cavity, forming transmitted and reflected light. Transmitted light passes through the cavity, while reflected light returns after reflection within the cavity. These two types of light are output from opposite sides of the cavity; this bidirectional output characteristic is a key feature of FP interferometer cavities.

[0004] Since transmitted and reflected light are emitted from different directions, a more complex optical path design is required to handle these two output rays. This may require additional optical components or optical path adjustments, increasing the complexity of the system. Utility Model Content

[0005] The technical problem to be solved by this utility model embodiment is to provide an optical filter and an optical communication device to solve the problem of complex optical paths in existing optical filters.

[0006] This utility model discloses an optical filter, comprising:

[0007] A first polarization output component is used to convert input light from a first side into single-polarized light output, wherein the single-polarized light has a target polarization direction;

[0008] A polarizing beam splitter is located on the second side of the first polarization output component, with the second side opposite to the first side. It can transmit light in the target polarization direction and reflect light in other polarization directions.

[0009] Two comb filters are located on two mutually perpendicular light-emitting directions of the polarizing beam splitter, and the filtering wavelength of each comb filter is adjustable. Each comb filter includes a GT resonant cavity.

[0010] Optionally, the comb filter includes a GT resonator assembly, the GT resonator assembly comprising:

[0011] A semi-transparent, semi-reflective mirror is positioned perpendicular to the light output direction of the polarizing beam splitter;

[0012] A quarter-wave plate, parallel to the semi-transparent mirror, is located on the side of the semi-transparent mirror away from the polarizing beam splitter;

[0013] The first total reflection mirror is parallel to the semi-transparent and semi-reflective mirror and is located on the side of the quarter-wave plate away from the polarizing beam splitter.

[0014] The distance between the semi-transparent mirror and the first total reflection mirror is adjustable.

[0015] Optionally, the comb filter further includes:

[0016] A displacement driving component, connected to the first total reflection mirror, is used to drive the first total reflection mirror to move closer to or away from the semi-transparent and semi-reflective mirror.

[0017] Optionally, the displacement drive assembly includes a piezoelectric ceramic actuator.

[0018] Optionally, the first polarization output component includes:

[0019] A polarization beam splitter is used to split the input light into a first polarized light having the target polarization direction and a second polarized light having the other polarization directions;

[0020] The first half-wave plate is used to change the polarization direction of the second polarized light to the target polarization direction, so that the second polarized light and the first polarized light can be combined into the single polarized light output.

[0021] Optionally, the optical filter further includes a second polarization output component, comprising:

[0022] A polarization beam combiner is located on the side of the polarization beam splitter away from the comb filter, and is used to receive the output light of the polarization beam splitter;

[0023] The second half-wave plate is used to change the polarization direction of a portion of the output light.

[0024] Optionally, the optical filter further includes:

[0025] The first single-fiber collimator is located on the side of the first polarization output component away from the polarization beam splitter;

[0026] The second single-fiber collimator is located on the side of the second polarization output component away from the polarization beam splitter;

[0027] Optionally, the first polarization output component is further configured to convert the single polarized light input from the second side into a mixed light output having the target polarization direction and the other polarization directions;

[0028] The optical filter also includes:

[0029] The second total reflection mirror is located on the side of the polarizing beam splitter away from the comb filter.

[0030] Optionally, the optical filter further includes:

[0031] A dual-fiber collimator is located on the side of the first polarization output component away from the polarization beam splitter.

[0032] This utility model also discloses an optical communication device, including the optical filter described above.

[0033] Compared with the prior art, the beneficial effects of the optical filter provided in this embodiment are as follows: The optical filter converts the signal light with mixed polarization directions into single polarized light with the target polarization direction through the first polarization output component. This output light is then transmitted through a polarizing beam splitter to a comb filter for filtering. After filtering with a specific wavelength, the light with other polarization directions in the output light is reflected by the polarizing beam splitter to another comb filter for further filtering. This other comb filter further filters the light according to another specific wavelength, thereby outputting light with the target wavelength. The filtering wavelengths of the two comb filters are adjustable, allowing users to output light with the target wavelength by reasonably setting the filtering wavelengths of the two comb filters, providing flexibility and adjustability to meet different needs. In this embodiment, both comb filters use GT resonant cavities to achieve the filtering effect, thus the light output directions are on the same side. Therefore, the optical path of the optical filter is simple, the structure is compact, which helps to reduce optical losses in the optical system and is also easy to maintain and adjust. Attached Figure Description

[0034] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0035] Figure 1 This is a schematic diagram of the structure of the first embodiment of the optical filter provided by this utility model;

[0036] Figure 2 This is a schematic diagram of the filtering effect of the optical filter provided by this utility model;

[0037] Figure 3 This is a schematic diagram of the structure of the GT resonant cavity assembly provided by this utility model;

[0038] Figure 4 This is the spectrum of the comb filter provided by this utility model;

[0039] Figure 5 This is a schematic diagram of the structure of the second embodiment of the optical filter provided by this utility model.

[0040] The labels for the attached figures are as follows:

[0041] 10. Optical filter; 11. First polarization output assembly; 111. Polarization beam splitter; 112. First half-wave plate; 12. Polarization beam splitter; 13. Comb filter; 131. Semi-transparent mirror; 132. Quarter-wave plate; 133. First total reflection mirror; 134. Displacement drive assembly; 14. Second polarization output assembly; 141. Polarization beam combiner; 142. Second half-wave plate; 15. First single-fiber collimator; 16. Second single-fiber collimator; 17. Second total reflection mirror; 18. Dual-fiber collimator. Detailed Implementation

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0043] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of the first embodiment of the optical filter provided by this utility model. The optical filter 10 includes a first polarization output component 11, a polarization beam splitter 12, and two comb filters 13. The first polarization output component 11 is used to convert input light from its first side (left side in the figure) into single-polarized light output. The single-polarized light has a target polarization direction. In this embodiment, the target polarization direction can be perpendicular to the light transmission direction (P-light), and correspondingly, other polarization directions are parallel to the light transmission direction (S-light). In other embodiments, the target polarization direction can be parallel to the light transmission direction (S-light), and correspondingly, other polarization directions are perpendicular to the light transmission direction (P-light).

[0044] The polarizing beam splitter 12 is located on the second side (right side in the figure) of the first polarizing output component 11. The polarizing beam splitter 12 can transmit light with the target polarization direction and reflect light with other polarization directions. The light input and output sides of the polarizing beam splitter 12 can be divided into a first side, a second side, a third side, and a fourth side, with the first side and the second, third, and fourth sides facing each other in pairs. The first polarizing output component 11 is located on the first side of the polarizing beam splitter 12, and two comb filters 13 are located on the second and third sides of the polarizing beam splitter, respectively. The polarizing beam splitter 12 is placed at an angle relative to the light transmission direction. Therefore, in this embodiment, the two comb filters 13 are located on two mutually perpendicular light output directions of the polarizing beam splitter 12. Figure 1 The middle section shows the upper and right sides of the polarizing beam splitter 12.

[0045] In this embodiment, the comb filter 13 includes a GT resonant cavity, so the light from the comb filter 13 is input and output from the same side, which makes the optical path of the optical filter 10 in this invention simple and does not require a complex structure.

[0046] In one embodiment, after the mixed light passes through the first polarization component on the left, it undergoes filtering and polarization direction adjustment by the first polarization component to become single polarized light (P-light) with the target polarization direction. The single polarized light (P-light) is input into the polarization beam splitter 12. Since the polarization beam splitter 12 can only transmit light with the target polarization direction, the single polarized light (P-light) can pass through the polarization beam splitter 12 and be directed to the comb filter 13 located on the second side. After filtering the single polarized light (P-light), the comb filter 13 on the second side outputs a first output light (P-light) with the target polarization direction and corresponding to the first target wavelength, and a second output light (S-light) with other polarization directions. The first output light (P-light) and the second output light (S-light) are directed to the polarization beam splitter 12. The second output light (S-light) is reflected by the polarization beam splitter 12 and directed to the comb filter 13 located on the third side of the polarization beam splitter 12, while the first output light (P-light) is dissipated into the air after being transmitted by the polarization beam splitter 12. The second output light (S-beam) is filtered by the comb filter 13 located on the third side of the polarizing beam splitter 12, and then outputs a third output light (P-beam) with a second target wavelength and a target polarization direction, and a fourth output light (S-beam) with other polarization directions. The third output light (P-beam) and the fourth output light (S-beam) are directed toward the polarizing beam splitter 12. The third output light (P-beam) is transmitted through the polarizing beam splitter 12 and then exits, while the fourth output light (S-beam) is reflected. The third output light (P-beam) can be used as the output of the optical filter 10.

[0047] The light will then pass through two comb filters 13 sequentially. The first comb filter 13 selects light of a first specific wavelength, while the second comb filter 13 further filters this light for a second specific wavelength. Their responses can be added together, and the spectra of the two comb filters 13 will be superimposed. The final signal spectrum will be the superposition of the spectra of the two comb filters 13. Please refer to [further details needed]. Figure 2 , Figure 2 This is a schematic diagram illustrating the filtering effect of the optical filter provided by this utility model. In this utility model, the filtering wavelength of each comb filter 13 is adjustable. By reasonably selecting the filtering wavelength of each comb filter 13 and superimposing the outputs of two comb filters 13, an optical signal output with the desired wavelength can be obtained. (See also...) Figure 2 It can be seen that the extinction ratio of the optical signal output by the optical filter 10 is concentrated in the range of -20dB to -50dB, which has a good extinction ratio.

[0048] Please refer to the following: Figure 3 and Figure 4 , Figure 3 This is a schematic diagram of the GT resonant cavity assembly provided by this utility model. Figure 4 This is the spectrum of the comb filter provided by this utility model.

[0049] The comb filter 13 includes a GT resonant cavity assembly, which includes: a semi-transparent mirror 131, which is set perpendicular to the light output direction of the polarizing beam splitter 12; a quarter-wave plate 132, which is parallel to the semi-transparent mirror 131 and located on the side of the semi-transparent mirror 131 away from the polarizing beam splitter 12; and a first total reflection mirror 133, which is parallel to the semi-transparent mirror 131 and located on the side of the quarter-wave plate 132 away from the polarizing beam splitter 12. A semi-transparent mirror can transmit some light and reflect some light back. Therefore, when light with a target polarization direction (P-light) is incident on the semi-transparent mirror 131, part of the light is reflected as outgoing light 101, and part of the light is transmitted into the GT resonant cavity assembly. The transmitted light is reflected twice by the first total reflection mirror 133, passes through the quarter-wave plate 132, and is incident on the semi-transparent mirror 131 again. Part of the light is reflected back into the GT resonant cavity assembly by the semi-transparent mirror 131, and part of the light passes through the semi-transparent mirror 131 and is emitted as outgoing light 102. The part of the transmitted light that returns to the GT resonant cavity assembly passes through the semi-transparent mirror 131 multiple times within the cavity, forming outgoing light 103, outgoing light 104, ... and outgoing light 10n, etc. Understandably, the polarization state of the transmitted signal light changes once every two round trips through the quarter-wave plate 132. Outgoing beams 103 and 105 are p-beams, while outgoing beams 102 and 104 are s-beams. According to the principle of coherence, coherent light must have the same polarization direction. Therefore, the p-beam portions of the outgoing light emitted from the GT resonator assembly interfere with each other, while the s-beam portions interfere with each other.

[0050] Specifically, let the incident light be E0, which can be represented by the Jones matrix as follows: Among them, E 0x For P, the light field intensity is E 0y For the S-field intensity, when the incident light is P-light, the normalized intensity can be set as... Assuming the initial phase of the incident signal light is 0, the reflection coefficient of the semi-transparent mirror 131 is r, and the transmission coefficient is t, then the light intensity of the outgoing light 101 is: For the emitted light 102 that travels back and forth once based on the GT resonant cavity component, its electric field transmission process can be described by the following formula:

[0051] The formula for the optical path length between the semi-transparent and semi-reflective unit 110 and the quarter-wave plate 130 is:

[0052]

[0053] Among them, E c1x E represents the field intensity of the p-beam after incident on a semi-transparent, semi-reflective element 110. c1y The light field intensity after 110 seconds of incident semi-transparent and semi-reflective unit.

[0054] The formula for the optical path length incident on the quarter-wave plate at 130° is:

[0055]

[0056] Among them, E c2x E is the field intensity of the p-type light incident on the quarter-wave plate at 130° on the outward path. c2y Let s be the light field intensity incident on the quarter-wave plate 130 on the outward path, and let J() be the Jones expression for the electric field of the quarter-wave plate 130.

[0057] The formula for the optical path length between the quarter-wave plate 130 and the total reflection unit 120 is:

[0058]

[0059] Among them, E c3x For the outgoing quarter-wave plate 130, the p-field intensity, E c3y The light field intensity 130s after the quarter-wave plate is emitted on the outgoing path.

[0060] The formula corresponding to position 120 of the total reflection unit is:

[0061]

[0062] Among them, E c4x E represents the light field intensity at the p-axis of the total internal reflection unit's 120° reflecting surface. c4y The light field intensity at the s-axis of the total reflection unit's 120 reflective surface is given.

[0063] The formula for the optical path length of the return journey between the quarter-wave plate 130 and the total reflection unit 120 is:

[0064]

[0065] Among them, E c5x E represents the field intensity of the p-beam after reflection from the total internal reflection unit 120. c5y The intensity of the light field after reflection from the total reflection unit 120 is s.

[0066] The formula for the optical path length corresponding to the return incident light onto the quarter-wave plate at 130° is:

[0067]

[0068] Among them, E c6x E is the field intensity of the p-type light when incident on a quarter-wave plate at 130° on the return journey. c6y The light field intensity at 130 s on the quarter-wave plate during the return journey.

[0069] The formula for the optical path length of the return journey between the quarter-wave plate 130 and the semi-transparent, semi-reflective unit 110 is:

[0070]

[0071] Among them, E c7x For the return quarter-wave plate 130 after the p-wave field intensity, E c7y The light field intensity 130s after the return quarter-wave plate.

[0072] Finally, the intensity of the emitted light 102 that passes through the semi-transparent and semi-reflective unit 110 again is:

[0073]

[0074] In the above formula, L1 represents the optical path length between the semi-transparent and semi-reflective unit 110 and the quarter-wave plate 130; L2 represents the optical path length between the quarter-wave plate 130 and the total reflection unit 120; i represents an imaginary number; e is the natural constant; π is pi; and λ represents the wavelength.

[0075] Similarly, E can be obtained. 101 E 102 E 103 E 104 E 105 The electromagnetic field strength is output after multiple reflections. By expanding the number of reflections, the output light intensity can be approximately expressed as:

[0076]

[0077] Where n is the number of emitted beams expanded, I x Let I be the intensity of the p-polarized emitted light, and I be the intensity of the emitted light. y The intensity of the emitted light is s-polarized light.

[0078] Based on the results of the above formula, we can obtain the following: Figure 4 The spectrum shows that the polarized p-light and s-light in the emitted light have a filtering effect similar to that of an FP cavity. At the same time, it can achieve the purpose of outputting light from one side of the GT resonant cavity component, that is, one side of the comb filter.

[0079] As described above, in this embodiment, the optical filter converts the mixed-polarization signal light into a single-polarization light with the target polarization direction through the first polarization output component. This output light is then transmitted through a polarizing beam splitter to a comb filter for filtering. This comb filter filters the light at a specific wavelength. Light with other polarization directions in the output light is reflected by the polarizing beam splitter to another comb filter for further filtering. This second comb filter further filters the light according to another specific wavelength, thus outputting light with the target wavelength. The filtering wavelengths of the two comb filters are adjustable, allowing the user to set the filtering wavelengths of the two comb filters appropriately to output light with the target wavelength, providing flexibility and adjustability to meet different needs. In this embodiment, both comb filters use GT resonant cavities to achieve the filtering effect, resulting in the light output direction being on the same side. Therefore, the optical path of the optical filter is simple, the structure is compact, which helps reduce optical losses in the optical system and is easy to maintain and adjust.

[0080] The filtering wavelength of the comb filter 13 can be adjusted by changing the distance between the semi-transparent mirror 131 and the first total reflection mirror 133. Adjusting the distance between the semi-transparent mirror 131 and the first total reflection mirror 133 changes the cavity length of the GT resonant cavity, which in turn changes the optical path length of light propagating inside the GT resonant cavity, and thus changes the filtering wavelength of the comb filter 13. Because light in the GT resonant cavity undergoes multiple reflections to form resonance conditions, adjusting the cavity length directly affects the operating wavelength range of the filter.

[0081] Please continue reading. Figure 1 The comb filter 13 also includes a displacement driving component 134, which is connected to the first total reflection mirror 133. This component adjusts the distance between the first total reflection mirror 133 and the semi-transparent mirror 131, thereby adjusting the distance between them. The displacement driving component 134 includes a piezoelectric ceramic actuator. The piezoelectric ceramic actuator has high stability and precision, ensuring the adjusted wavelength remains stable and preventing wavelength drift or instability from affecting the experiment or system. Furthermore, the piezoelectric ceramic actuator can achieve minute displacement adjustments, thus precisely controlling the filtering wavelength of the comb filter 13.

[0082] Please continue reading. Figure 1The first polarization output component 11 includes a polarization beam splitter 111 and a first half-wave plate 112. The polarization beam splitter 111 can split the incident light into different beams according to its polarization state. In this embodiment, the input light is split into a first polarized light (P-light) with a target polarization direction and a second polarized light (S-light) with other polarization directions. The first half-wave plate 112 can change the polarization state of the light. When linearly polarized light passes through the half-wave plate, its polarization state changes. When the second polarized light (S-light) (propagating along the fast axis of the first half-wave plate 112) passes through, it becomes light with the target polarization direction (P-light) (propagating along the slow axis of the plate), thereby integrating the second polarized light and the first polarized light after the polarization state change into a single polarized light (P-light) for output. The combination of the polarization beam splitter 111 and the half-wave plate configuration can effectively control and adjust the polarization state of the light, realize the integration and output of light with different polarization states, and at the same time improve the light intensity of the single polarized light of the input polarization beam splitter 12, ensuring that the intensity of the output light of the optical filter 10 meets the requirements.

[0083] The third output light (P-beam), after being transmitted through polarizing beam splitter 12, requires further processing to meet user needs. Please continue reading. Figure 1 The optical filter 10 also includes a second polarization output component 14, which includes a polarization combiner 141 and a second half-wave plate 142. The polarization combiner 141 is located on the side of the polarization beam splitter 12 away from the comb filter 13, i.e., the fourth side, and is used to receive the output light (third output light (P-light)) of the polarization beam splitter 12. The second half-wave plate 142 is used to change the polarization direction of a portion of the output light. Specifically, the polarization beam splitter 12 transmits a third output light (P-light) containing only one polarization state. Therefore, by adjusting the polarization state of a portion of the third output light (P-light) using the second half-wave plate 142, output light (S-light) with other polarization directions is obtained. Combining this portion of light (S-light) with the remaining portion of the third output light (P-light) yields a target output light with a mixed polarization state. The mixed polarization state output light can play an important role in some optical experiments and systems.

[0084] Furthermore, to improve the accuracy of optical filtering and reduce light transmission loss, in this embodiment, the optical filter 10 further includes: a first single-fiber collimator 15 and a second single-fiber collimator 16. The first single-fiber collimator 15 is located on the side of the first polarization output component 11 away from the polarization beam splitter 12; the second single-fiber collimator 16 is located on the side of the second polarization output component 14 away from the polarization beam splitter 12. This allows light to be collimated when input to the optical filter 10, reducing the defocusing effect and making the light propagation in the system more stable. This reduces aberrations and defocusing phenomena in the optical system, reduces light loss, and improves the optical efficiency of the optical system. Collimation also occurs when outputting to the optical filter 10, making the light more concentrated and parallel, thus improving the performance of the output light.

[0085] Please refer to the following: Figure 5 , Figure 5 This is a schematic diagram of the structure of the second embodiment of the optical filter provided by this utility model. In this embodiment, the first polarization output component 11, in addition to outputting from the first side ( Figure 2 The input light (from the left side) is converted into a single-polarized light (P-light) with the target polarization direction and output, and is also used to extract light from the second side ( Figure 2 The single-polarized light (P-light) input (on the right side of the middle section) is converted into a mixed light output with a target polarization direction and other polarization directions. The optical filter 10 also includes a second total reflection mirror 17, located on the side of the polarization beam splitter 12 away from the comb filter 13. A dual-fiber collimator 18 is located on the side of the first polarization output assembly 11 away from the polarization beam splitter 12. One fiber connected to the dual-fiber collimator 18 is used for the input optical signal, and the other fiber is used for the output optical signal.

[0086] The functions and structures of the polarizing beam splitter 12 and the two comb filters 13 in the optical filter 10 of this embodiment are basically the same as those in the first embodiment of the optical filter 10 provided by this utility model, and will not be described again here. After the third output light (P light) is transmitted through the polarizing beam splitter 12, it will be emitted and then hit the second total reflection mirror 17. After being reflected by the second total reflection mirror 17, it returns along the same path and is then filtered by the two comb filters 13 before being output. The extinction ratio of the output light will be better than that of the output light in the first embodiment of the optical filter 10 provided by this utility model. The light passes through the two comb filters 13 twice, which performs double filtering, which can improve the filtering effect on specific wavelengths, thereby improving the extinction ratio of the output light.

[0087] In this embodiment, the portion of the output light with the target polarization direction can be transmitted through the polarization beam splitter 12. Therefore, the output light of the polarization beam splitter 12 is P-light. At this time, the polarization state of part of the output light is changed by the first half-wave plate 112 to obtain S-light with other polarization directions. After the S-light and the remaining P-light are integrated, they are collimated by the dual-fiber collimator 18 and then output through another optical fiber.

[0088] As described above, in this embodiment, by setting a second total internal reflection mirror on the light-emitting side of the polarizing beam splitter, the light can return along its original path and be filtered again by two comb filters before being output, which effectively improves the extinction ratio of the output light and the utilization rate of the comb filters. The overall structure is compact and the optical path is simple.

[0089] This utility model also discloses an optical communication device, including the optical filter 10 in the foregoing embodiments. The optical filter 10 has the same structure and beneficial effects as the optical filter 10 in the foregoing embodiments. The structure and beneficial effects of the optical filter 10 have been described in detail in the foregoing embodiments and will not be repeated here.

[0090] It should be understood that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of this utility model.

Claims

1. An optical filter, characterized in that, include: A first polarization output component is used to convert input light from a first side into single-polarized light output, wherein the single-polarized light has a target polarization direction; A polarizing beam splitter is located on the second side of the first polarization output component, with the second side opposite to the first side. It can transmit light in the target polarization direction and reflect light in other polarization directions. Two comb filters are located on two mutually perpendicular light-emitting directions of the polarizing beam splitter, and the filtering wavelength of each comb filter is adjustable. Each comb filter includes a GT resonant cavity.

2. The optical filter according to claim 1, characterized in that, The comb filter includes a GT resonant cavity assembly, which includes: A semi-transparent, semi-reflective mirror is positioned perpendicular to the light output direction of the polarizing beam splitter; A quarter-wave plate, parallel to the semi-transparent mirror, is located on the side of the semi-transparent mirror away from the polarizing beam splitter; The first total reflection mirror is parallel to the semi-transparent and semi-reflective mirror and is located on the side of the quarter-wave plate away from the polarizing beam splitter. The distance between the semi-transparent mirror and the first total reflection mirror is adjustable.

3. The optical filter according to claim 2, characterized in that, The comb filter further includes: A displacement driving component, connected to the first total reflection mirror, is used to drive the first total reflection mirror to move closer to or away from the semi-transparent and semi-reflective mirror.

4. The optical filter according to claim 3, characterized in that, The displacement drive assembly includes a piezoelectric ceramic actuator.

5. The optical filter according to claim 1, characterized in that, The first polarization output component includes: A polarization beam splitter is used to split the input light into a first polarized light having the target polarization direction and a second polarized light having the other polarization directions; The first half-wave plate is used to change the polarization direction of the second polarized light to the target polarization direction, so that the second polarized light and the first polarized light can be combined into the single polarized light output.

6. The optical filter according to claim 5, characterized in that, The optical filter further includes a second polarization output component, comprising: A polarization beam combiner is located on the side of the polarization beam splitter away from the comb filter, and is used to receive the output light of the polarization beam splitter; The second half-wave plate is used to change the polarization direction of a portion of the output light.

7. The optical filter according to claim 6, characterized in that, The optical filter also includes: The first single-fiber collimator is located on the side of the first polarization output component away from the polarization beam splitter; The second single-fiber collimator is located on the side of the second polarization output component away from the polarization beam splitter.

8. The optical filter according to claim 5, characterized in that, The first polarization output component is also used to convert the single polarized light input from the second side into a mixed light output having the target polarization direction and the other polarization directions; The optical filter also includes: The second total reflection mirror is located on the side of the polarizing beam splitter away from the comb filter.

9. The optical filter according to claim 8, characterized in that, The optical filter also includes: A dual-fiber collimator is located on the side of the first polarization output component away from the polarization beam splitter.

10. An optical communication device, characterized in that, Includes the optical filter as described in any one of claims 1-9.

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