Optical filter and spectrometer

Abstract

The utility model discloses an optical filter and a spectrograph, the optical filter (100) comprises multiple stages of passive filtering units (300), in two adjacent stages of passive filtering units (300), the output end of the previous stage of passive filtering unit (300) is connected with the input end of the next stage of passive filtering unit (300), and the output end of the next stage of passive filtering unit (300) is connected with the output end of the next stage of passive filtering unit (300). The passive filtering unit (300) is used for filtering and modulating an incident optical signal, so that the optical signal processed by the previous-stage passive filtering unit (300) enters the next-stage passive filtering unit (300), and the passive filtering unit (300) is used for filtering and modulating the incident optical signal; and the multiple stages of passive filtering units (300) are respectively used for modulating light with different wavelengths. The optical filter and the spectrometer provided by the utility model have the advantages of low power consumption and miniaturization.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of spectrum analysis technology, specifically relates to a light filter and spectrometer. BACKGROUND

[0002] Spectrum analysis is a scientific method based on the interaction between matter and light, which uses the absorption, emission or scattering characteristics of matter to specific wavelengths of light to identify and analyze matter. Each kind of matter has its unique spectral characteristics, which reflect the energy level structure of its molecules or atoms. By measuring these spectral characteristics, the chemical composition and structure of the matter can be determined. This technology is currently mainly applied in environmental monitoring, chemical pharmaceutical, high-end medical, food and agricultural and sideline fields.

[0003] The current spectrometer includes an optical module, a light filter and a photodetector. The optical module emits probe light to irradiate on the object to be detected, collects the reflected light of the object to be detected, and guides the light to the light filter. The light filter modulates light of different wavelengths and transmits the optical signal to the photodetector. The photodetector receives the optical signal, and the spectrometer performs spectral analysis on the reflected light by means of a calculation algorithm to determine the performance parameters of the detected substance.

[0004] How to provide a new type of spectrometer is the pursuit of the field. UTILITY MODEL CONTENT

[0005] The utility model aims at solving one of the technical problems in the related art to some extent. To this end, the utility model provides a spectrometer, which has the advantages of low power consumption and small size.

[0006] In order to achieve the above purpose, as a first aspect of the utility model, a light filter is provided, wherein the light filter comprises a plurality of passive filter units. In adjacent two passive filter units, the output end of the former passive filter unit is connected with the input end of the latter passive filter unit, so that the optical signal processed by the former passive filter unit enters the latter passive filter unit.

[0007] The passive filter unit is used for filtering and modulating the incident optical signal. The plurality of passive filter units are respectively used for modulating light of different wavelengths.

[0008] Optionally, the passive filter unit comprises a straight waveguide, a ring waveguide and a directional coupler. The ring waveguide is located on one side of the straight waveguide, and the directional coupler is arranged on the straight waveguide. The directional coupler connects the straight waveguide and the ring waveguide. The straight waveguide of the former passive filter unit is connected with the straight waveguide of the latter passive filter unit. The optical signal output by the straight waveguide of the former passive filter unit enters the straight waveguide of the latter passive filter unit.

[0009] Optionally, the ring waveguide corresponds to the directional coupler one by one, and the optical filter comprises a plurality of ring waveguidances with different ring lengths.

[0010] Optionally, the passive filter unit comprises a straight waveguide, a light splitting element and two interference arms; the light splitting element is located between the straight waveguide and the two interference arms; the two interference arms have different arm lengths; the two interference arms of the previous-stage passive filter unit are connected to the straight waveguide of the next-stage passive filter unit; the optical signals output by the two interference arms of the previous-stage passive filter unit enter the straight waveguide of the next-stage passive filter unit.

[0011] Optionally, the optical filter comprises a plurality of interference arms with different arm lengths.

[0012] Optionally, the passive filter unit further comprises an optical waveguide and a plurality of groups of mirrors; the mirrors in each group are arranged in a row in the optical waveguide at a preset distance; the output of a mirror in a previous group enters a mirror in a next group after being transmitted in the optical waveguide for a preset distance; the mirror of the previous-stage passive filter unit is connected to the optical waveguide of the next-stage passive filter unit; the optical signals output by the mirror of the previous-stage passive filter unit enter the optical waveguide of the next-stage passive filter unit.

[0013] Optionally, the mirrors in each group comprise a plurality of mirrors with the same size; the mirrors in different groups have different sizes.

[0014] Optionally, the passive filter unit comprises a straight waveguide, two light splitting elements, two interference arms, a directional coupler and a ring waveguide; the light splitting elements and the directional coupler are arranged on the straight waveguide; the interference arms are arranged between the light splitting elements; the directional coupler connects the straight waveguide and the ring waveguide; the straight waveguide of the previous-stage passive filter unit is connected to the straight waveguide of the next-stage passive filter unit; the optical signals output by the straight waveguide of the previous-stage passive filter unit enter the straight waveguide of the next-stage passive filter unit.

[0015] Optionally, the optical filter comprises a plurality of interference arms with different arm lengths and a plurality of ring waveguidances with different ring lengths.

[0016] Further, the utility model discloses a kind of optical spectrum analyzer in the second aspect, described optical spectrum analyzer includes focusing lens, detector and shell, wherein, described optical spectrum analyzer further includes the optical filter of the first aspect, the optical filter covers the detector;Multiple light sources are arranged around the focusing lens, the detector is arranged at the side of the focusing lens away from the object to be detected;The shell is formed with opening;The light source emits detection light towards the opening, the focusing lens collects the light reflected by the object to be detected and guides to the optical filter covering the detector;The optical filter is transmitted to the detector after filtering and modulation to the optical signal.

[0017] The optical filter includes multiple passive filter units, the output end of the front-stage passive filter unit is connected with the input end of the rear-stage passive filter unit, the passive filter unit is used for filtering and modulating the input signal, and the multiple passive filter units are used for selecting and modulating light of different wavelengths. The optical filter has the function of adjusting the filter characteristics through the combination of passive filter units, and through the multiple combinations, the specific spectral response curve can be realized, and the detection requirements for specific substances or specific wave bands are met. Since the energy consumption of active devices is avoided, the optical filter has the significant feature of low power consumption.

[0018] Further, the optical spectrum analyzer is arranged in a ring around the optical axis of the focusing lens, and the detector is arranged on the side of the focusing lens away from the object to be detected, so that the optical module and the detector are closely combined, and the volume of the optical spectrum analyzer is effectively reduced.

[0019] The features and advantages of the utility model will be disclosed in detail in the following specific embodiments and drawings. The best embodiment or means of the utility model will be fully embodied in combination with the drawings, but is not limited to the technical scheme of the utility model. In addition, the features, elements and components appearing in each of the following text and drawings are multiple, and different symbols or numbers are marked for the convenience of representation, but all represent the same or similar structure or function parts. BRIEF DESCRIPTION OF DRAWINGS

[0020] The utility model will be further described in combination with the drawings as follows:

[0021] Figure 1 It is structural schematic view of the optical filter in one embodiment of the utility model.

[0022] Figure 2 It is structural view of the optical filter in one embodiment of the utility model.

[0023] Figure 3 It is structural view of the optical filter in one embodiment of the utility model.

[0024] Figure 4 A structure diagram of the optical filter in an embodiment of the utility model.

[0025] Figure 5 A structure diagram of the optical filter in an embodiment of the utility model.

[0026] Figure 6 A structure diagram of the optical spectrum analyzer in an embodiment of the utility model.

[0027] Figure 7 A structure diagram of the optical spectrum analyzer chip mounting portion in an embodiment of the utility model.

[0028] Figure 8 A structure diagram of the optical spectrum analyzer in an embodiment of the utility model.

[0029] BRIEF DESCRIPTION OF DRAWINGS

[0030] Wherein, 100, optical filter;300, passive filter unit;301, straight waveguide;302, ring waveguide;303, directional coupler;304, light splitting element;305, interference arm;306, optical waveguide;307, mirror;400, optical spectrum analyzer;401, focusing lens;402, detector;403, shell;404, light source;4041, light emitting element;4042, collimating lens;405, opening;406, partition;701, substrate;702, detector lens. DETAILED DESCRIPTION

[0031] Embodiments of the utility model are described in detail below, examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. Based on the embodiments in the embodiments, it is intended to explain the utility model, and cannot be understood as a limitation of the utility model.

[0032] In the present specification, "one embodiment" or "an example" or "an example" means that the specific features, structures or characteristics described in connection with the embodiment itself can be included in at least one embodiment of the utility model disclosure. The appearance of the phrase "in one embodiment" at various positions in the specification does not necessarily refer to the same embodiment.

[0033] In related spectral technology, the filtering characteristics of the active filter can be adjusted by applying additional electrical signals or thermal signals to achieve a specific spectral response curve to complete the detection requirements of the substance. This method needs to consume additional energy, and the power consumption is large.

[0034] In spectral technology, active filters usually include active devices such as optical amplifiers, electro-optical modulators, and wavelength selectors. Optical amplifiers are used to enhance the intensity of optical signals, and electro-optical modulators can change the characteristics of light (such as phase, amplitude, etc.) according to the applied electrical signal, thereby achieving filtering and adjustment of optical signals. The wavelength selector completes the tuning by changing the refractive index, optical path difference, and realizes the selection of specific wavelength light. By adjusting the filtering characteristics of the filter, a specific spectral response curve can be achieved to meet the detection requirements of specific substances or specific wavebands. In active filters, external excitation such as electrical signals or thermal signals is required to change the optical properties, which has the problem of high power consumption.

[0035] Therefore, as a first aspect of the present application, an optical filter 100 is provided, wherein the optical filter 100 comprises a plurality of passive filter units 300, and in adjacent two passive filter units 300, the output end of the former passive filter unit 300 is connected to the input end of the latter passive filter unit 300, so that the optical signal processed by the former passive filter unit 300 enters the latter passive filter unit 300, and the passive filter unit 300 is used for filtering and modulating the incident optical signal. Figure 1

[0036] The optical filter 100 provided by the present application comprises a plurality of passive filter units 300, and the output end of the former passive filter unit 300 is connected to the input end of the latter passive filter unit 300. The passive filter unit 300 is used for filtering and modulating the input signal, and the plurality of passive filter units 300 are used for selecting and modulating light of different wavelengths. This optical filter 100 has the function of adjusting the filter characteristics through the combination of passive filter units 300, and through multi-stage combination, a specific spectral response curve can be achieved to meet the detection requirements of specific substances or specific wavebands. Since the energy consumption of active devices is avoided, the optical filter 100 has the significant feature of low power consumption.

[0037] The optical filter 100 provided by the present application comprises a plurality of passive filter units 300, and the output end of the former passive filter unit 300 is connected to the input end of the latter passive filter unit 300. The passive filter unit 300 is used for filtering and modulating the input signal, and the plurality of passive filter units 300 are used for selecting and modulating light of different wavelengths. This optical filter 100 has the function of adjusting the filter characteristics through the combination of passive filter units 300, and through multi-stage combination, a specific spectral response curve can be achieved to meet the detection requirements of specific substances or specific wavebands. Since the energy consumption of active devices is avoided, the optical filter 100 has the significant feature of low power consumption.

[0038] In the present application, the specific structure of the passive filter unit 300 is not specially limited, as long as it can modulate light of a specific wavelength.

[0039] ​As an optional implementation, the passive filtering unit 300 includes a linear waveguide 301, a ring waveguide 302, and a directional coupler 303; the ring waveguide 302 is located on one side of the linear waveguide 301, and the directional coupler 303 is disposed on the linear waveguide 301, connecting the linear waveguide 301 and the ring waveguide 302; the linear waveguide 301 of the previous passive filtering unit 300 is connected to the linear waveguide 301 of the next passive filtering unit 300; the optical signal output from the linear waveguide 301 of the previous passive filtering unit 300 enters the linear waveguide 301 of the next passive filtering unit 300.

[0040] Furthermore, as an optional implementation, the ring waveguide 302 corresponds one-to-one with the directional coupler 303, and the optical filter 100 includes multiple ring waveguides 302 with inconsistent ring lengths.

[0041] like Figure 2 The diagram shows a structure of an optical filter 100, including a linear waveguide 301, four directional couplers 303, and four ring waveguides 302. The four directional couplers 303 are all disposed on the linear waveguide 301, and the four ring waveguides 302 are all disposed on one side of the linear waveguide 301. The four directional couplers 303 are respectively connected to the ring waveguides 302 and the linear waveguide 301.

[0042] Incident light enters from the left and propagates along the straight waveguide 301. Upon encountering the first directional coupler 303, a portion of the light couples into the first ring waveguide 302, while the remaining light continues propagating to the right along the straight waveguide 301. In the ring waveguide 302, the light propagates along its path. Due to the resonant characteristics of the ring waveguide 302, light of specific wavelengths resonates, while other wavelengths gradually attenuate. After resonance in the ring waveguide 302, a portion of the light returns to the straight waveguide 301 via the directional coupler 303, continuing to propagate to the right with the following light. This process is repeated at each subsequent directional coupler 303 and ring waveguide 302. Finally, the light passes through multiple stages of passive filtering units 300 and is output from the right side. Changing the ring length of the ring waveguide 302 in the passive filter unit 300 can achieve phase modulation of light. The directional coupler 303 in the passive filter unit 300 can not only couple light from the straight waveguide 301 into the ring waveguide 302 and back from the ring waveguide 302 into the straight waveguide 301, but its coupling coefficient can also affect the propagation characteristics of light throughout the entire structure. Changing the coupling coefficient affects the energy distribution of light between the ring waveguide 302 and the straight waveguide 301, indirectly affecting the phase of the light. By adjusting the phase of the optical filter 100, the filtering characteristics of the filter can be further adjusted to achieve a specific spectral response curve.

[0043] As an optional implementation, the passive filter unit 300 comprises a straight waveguide 301, a light splitting element 304 and two interference arms 305; the light splitting element 304 is located between the straight waveguide 301 and the two interference arms 305; the two interference arms 305 have different arm lengths; the two interference arms 305 of the former-stage passive filter unit 300 are connected to the straight waveguide 301 of the latter-stage passive filter unit 300; the light signals output by the two interference arms 305 of the former-stage passive filter unit 300 enter the straight waveguide 301 of the latter-stage passive filter unit 300.

[0044] Further, as an optional implementation, the optical filter 100 comprises a plurality of interference arms 305 with different arm lengths.

[0045] As shown in FIG. 1, the optical filter 100 comprises a straight waveguide 301, a light splitting element 304 and two interference arms 305. Figure 3 As shown in FIG. 2, the optical filter 100 comprises a straight waveguide 301, six light splitting elements 304 and five groups of interference arms 305, each group of interference arms 305 comprises two interference arms 305 with different arm lengths, the light splitting elements 304 are arranged on the straight waveguide 301, and each group of interference arms 305 is arranged after the light splitting element 304.

[0046] The incident light enters from the left side and propagates along the straight waveguide 301, when encountering the first light splitting element 304, the light splitting element 304 splits the incident light into two beams, one beam enters the upper interference arm 305 of the first group of interference arms 305, and the other beam enters the lower interference arm 305 of the first group of interference arms 305, the two beams propagate in the respective interference arms 305, and due to the different lengths of the interference arms 305, the optical paths of the two beams in the two arms are different. After a distance of propagation, the two beams converge again at the subsequent light splitting element 304. The converged light continues to propagate to the next passive filter unit 300, and the above-mentioned splitting, propagating and converging processes are repeated, and finally output from the right side after passing through the multiple-stage passive filter units 300. Due to the different lengths of the upper and lower interference arms 305 in each passive filter unit 300, the optical paths of the two beams in the two arms are different, and according to prior knowledge, the difference in optical path will cause a phase difference between the two beams, therefore, the optical filter 100 structure can realize filtering and phase modulation of light with different wavelength ranges in each passive filter unit 300.

[0047] As an optional embodiment, the passive filter unit 300 further comprises an optical waveguide 306 and a plurality of groups of mirrors 307, which are arranged in rows in the optical waveguide 306 at a preset distance; the output of a previous group of mirrors 307 enters a next group of mirrors after transmitting in the optical waveguide 306 for a preset distance; the mirrors 307 of a previous-stage passive filter unit 300 are connected to the optical waveguide 306 of a next-stage passive filter unit 300; the light signal output by the mirrors 307 of the previous-stage passive filter unit 300 enters the optical waveguide 306 of the next-stage passive filter unit 300.

[0048] Further, as an optional embodiment, the mirrors 307 in the same group are of the same size, and the mirrors 307 in different groups are of different sizes.

[0049] As shown in FIG. 1, the light filter 100 comprises an optical waveguide 306 and n groups of mirrors 307, the distance between each group of mirrors 307 is different, and each group of mirrors 307 comprises three mirrors 307 of the same size, and the mirrors 307 in different groups are of different sizes. Figure 4

[0050] After the incident light enters the optical waveguide 306 from the left, it propagates along the optical waveguide 306 to the right. When the light reaches the first mirror 307, part of the light is reflected back to the optical waveguide 306, and the other part of the light continues to propagate to the right. The transmitted light successively reaches the subsequent mirrors 307, and similar reflection and transmission phenomena occur at each mirror 307. In this way, the light is constantly reflected and transmitted between the mirrors 307, forming a combination of multiple reflected and transmitted lights, which are superimposed and interfered with each other in the optical waveguide 306. According to the principle of light interference, the interference result of two lights depends on the phase difference between them, and the phase difference is related to the optical path. In this structure of the light filter 100, the distance that the light propagates between adjacent mirrors 307 is part of the optical path, and changing the distance between the mirrors 307 changes the optical path difference, which in turn causes the phase difference to change, achieving phase modulation.

[0051] As an optional embodiment, the passive filter unit 300 comprises a straight waveguide 301, two light splitting elements 304, two interference arms 305, a directional coupler 303 and a ring waveguide 302; the light splitting elements 304 and the directional coupler 303 are arranged on the straight waveguide 301; the interference arms 305 are arranged between the light splitting elements 304, and the directional coupler 303 connects the straight waveguide 301 and the ring waveguide 302; the straight waveguide 301 of a previous-stage passive filter unit 300 is connected to the straight waveguide 301 of a next-stage passive filter unit 300; the light signal output by the straight waveguide 301 of the previous-stage passive filter unit 300 enters the straight waveguide 301 of the next-stage passive filter unit 300.​

[0052] Furthermore, as an optional implementation, the optical filter 100 includes multiple interferometer arms 305 with different arm lengths and multiple ring waveguides 302 with inconsistent ring lengths.

[0053] like Figure 5 The optical filter 100 structure shown includes a linear waveguide 301, six beam splitters 304, three sets of interferometer arms 305, three ring waveguides 302, and three directional couplers 303. The beam splitters 304 and directional couplers 303 are all disposed on the linear waveguide 301, and the ring waveguides 302 are all disposed on one side of the linear waveguide 301. Each set of interferometer arms 305 is disposed between two beam splitters 304; the directional couplers 303 connect the ring waveguides 302 and the linear waveguides 301 respectively.

[0054] The incident light enters the linear waveguide 301 from the left. After passing through the beam splitter 304, it is split into two beams. One beam propagates along the interferometer arm 305 above the first set of interferometer arms 305, while the other beam propagates along the interferometer arm 305 below the first set of interferometer arms 305. After propagating for a distance, the two beams merge again at the subsequent beam splitter 304 and continue propagating on the linear waveguide 301. When it encounters the first directional coupler 303, part of the light couples into the first ring waveguide 302, while the remaining light continues to propagate to the right along the linear waveguide 301. The light entering the ring waveguide 302 will experience a resonance effect due to the resonant characteristics of the ring waveguide 302. After resonance in the ring waveguide 302, part of the light will return to the linear waveguide 301 through the directional coupler 303 and continue to propagate to the right with the subsequently propagating light. After passing through multiple stages of passive filter units 300, the light is finally output from the right side. Since each passive filtering unit 300 of the optical filter 100 includes a ring waveguide 302, interferometer arms 305 with different arm lengths, and a directional coupler 303 with adjustable coupling coefficient, high-precision filtering and phase modulation functions can be achieved by adjusting the ring length of the ring waveguide 302, the difference in arm lengths of the interferometer arms 305, and the coefficient of the directional coupler 303 in each passive filtering unit 300.

[0055] As a second aspect of the utility model, a spectrometer 400 is provided, the spectrometer 400 includes focusing lens 401, detector 402 and shell 403, wherein, the spectrometer 400 further includes the light filter 100 of first aspect, and the light filter 100 covers detector 402, multiple light sources 404 are arranged around focusing lens 401, and detector 402 is arranged at the side of focusing lens 401 away from the object to be detected, and the shell 403 is formed with opening 405, and the light source 404 emits detection light towards opening 405, and focusing lens 401 collects the light reflected by the object to be detected and guides to the light filter 100 covering detector 402, and the light filter 100 transmits to detector 402 after filtering and modulating optical signal.

[0056] The structure of the spectrometer 400 is shown in Figure 6 The internal space of the shell 403 of the spectrometer 400 is divided into a light source accommodating portion, a lens accommodating portion and a detector accommodating portion, and all are located on the same side of the opening 405 of the shell 403, the light source accommodating portion and the lens accommodating portion are separated by a partition 406, multiple light source accommodating portions are arranged around the lens accommodating portion, and the light source accommodating portion and the lens accommodating portion are both formed with an opening 405, and the detector accommodating portion is arranged on the side of the lens accommodating portion away from the opening 405.

[0057] The three internal spaces of the spectrometer 400 are described in detail as follows. The detector accommodating portion is used to fix the detector 402. The detector accommodating portion is provided with a substrate 701, a detector lens 702 and a detector 402, the detector lens 702 and the detector 402 are installed on one side of the substrate 701, the other side of the substrate 701 is fixed to the inner surface of the detector accommodating portion of the shell 403, and the detector 402 is arranged on the focusing surface of the detector lens 702, as shown in Figure 7 .

[0058] For the lens accommodating portion of the spectrometer 400, it is used to converge the light reflected by the object to be detected and guide the light to the detector accommodating portion. The lens accommodating portion is provided with a focusing lens 401 and a reflector 307, the reflector 307 is located on the side of the focusing lens 401 away from the opening 405, the included angle between the reflecting surface of the reflector 307 and the focusing lens 401 is between 40° and 50°, and the reflector 307 is used to reflect the light to the detector accommodating portion.

[0059] For the light source accommodating portion of the spectrometer 400, it is used to emit detection light towards the object to be detected, and the light source accommodating portion is provided with a light emitting element 4041 and a collimating lens 4042, the collimating lens 4042 is arranged on the light emitting side of the light emitting element 4041, and the light emitting element 4041 and the collimating lens 4042 correspond one by one.

[0060] The collimating lens 4042 and the mirror 307 in the spectrometer 400 can be configured according to actual detection requirements to improve the proportion of the light signal reflected by the object to be detected acquired by the detector 402. Figure 8 Another structure diagram of the spectrometer 400 is given.

Claims

1. An optical filter, characterized by, The optical filter (100) comprises a plurality of passive filter units (300), and in two adjacent passive filter units (300), the output end of the former passive filter unit (300) is connected to the input end of the latter passive filter unit (300), so that the optical signal processed by the former passive filter unit (300) enters the latter passive filter unit (300), The passive filter unit (300) is used for filtering and modulating the incident optical signal; and the plurality of passive filter units (300) are respectively used for modulating optical signals of different wavelengths.

2. The optical filter of claim 1, wherein, The passive filter unit (300) comprises a straight waveguide (301), a ring waveguide (302) and a directional coupler (303); the ring waveguide (302) is located on one side of the straight waveguide (301), the directional coupler (303) is arranged on the straight waveguide (301), and the directional coupler (303) connects the straight waveguide (301) and the ring waveguide (302); the straight waveguide (301) of the former passive filter unit (300) is connected to the straight waveguide (301) of the latter passive filter unit (300); and the optical signal output by the straight waveguide (301) of the former passive filter unit (300) enters the straight waveguide (301) of the latter passive filter unit (300).

3. The optical filter of claim 2, wherein, The ring waveguide (302) corresponds to the directional coupler (303) one by one, and the optical filter (100) comprises a plurality of ring waveguides (302) with different ring lengths.

4. The optical filter of claim 1, wherein, The passive filter unit (300) comprises a straight waveguide (301), a light splitting element (304) and two interference arms (305); the light splitting element (304) is located between the straight waveguide (301) and the two interference arms (305); the two interference arms (305) have different arm lengths; the two interference arms (305) of the former passive filter unit (300) are connected to the straight waveguide (301) of the latter passive filter unit (300); and the optical signal output by the two interference arms (305) of the former passive filter unit (300) enters the straight waveguide (301) of the latter passive filter unit (300).

5. The optical filter of claim 4, wherein, The optical filter (100) comprises a plurality of interference arms (305) with different arm lengths.

6. The optical filter of claim 1, wherein, The passive filter unit (300) further comprises an optical waveguide (306) and a plurality of groups of mirrors (307), the plurality of groups of mirrors (307) are arranged in rows in the optical waveguide (306) at a pre-set distance; the output of a former group of mirrors (307) enters a latter group of mirrors after being transmitted in the optical waveguide (306) for a pre-set distance; the mirrors (307) of the former passive filter unit (300) are connected to the optical waveguide (306) of the latter passive filter unit (300); and the optical signal output by the mirrors (307) of the former passive filter unit (300) enters the optical waveguide (306) of the latter passive filter unit (300).

7. The optical filter of claim 6, wherein, The same group of mirrors (307) comprises a plurality of mirrors (307) with the same size; the different groups of mirrors (307) are all inconsistent in size.

8. The optical filter of claim 1, wherein, The passive filter unit (300) comprises a straight waveguide (301), two light splitting elements (304), two interference arms (305), a directional coupler (303) and a ring waveguide (302); the light splitting elements (304) and the directional coupler (303) are arranged on the straight waveguide (301); the interference arms (305) are arranged between the light splitting elements (304), and the directional coupler (303) connects the straight waveguide (301) and the ring waveguide (302); the straight waveguide (301) of a previous-stage passive filter unit (300) is connected with the straight waveguide (301) of a next-stage passive filter unit (300); the light signal output by the straight waveguide (301) of the previous-stage passive filter unit (300) enters the straight waveguide (301) of the next-stage passive filter unit (300).

9. The optical filter of claim 8, wherein, The optical filter (100) comprises a plurality of interference arms (305) with different arm lengths and a plurality of ring waveguides (302) with inconsistent ring lengths.

10. A spectrometer, the spectrometer (400) comprising a focusing lens (401), a detector (402) and a housing (403), characterized in that, The optical spectrum analyzer (400) further comprises the optical filter (100) of any one of claims 1 to 9, the optical filter (100) covering the detector (402); a plurality of light sources (404) are arranged around the focusing lens (401), and the detector (402) is arranged on the side of the focusing lens (401) away from the object to be detected; the shell (403) is formed with an opening (405); the light sources (404) emit detection light towards the opening (405), the focusing lens (401) collects light reflected by the object to be detected and guides the light to the optical filter (100) covering the detector (402); the optical filter (100) filters and modulates the light signal and then transmits the light signal to the detector (402).

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