Micro FP Cavity Narrow Band Filter

Abstract

A miniature FP cavity narrowband filter includes a miniature packaged filter structure. Internal devices are integrated into the same miniature package body through optical micromachining technology. The internal devices include: a semiconductor refrigerator, an FP cavity, a thermistor, an optical fiber and a collimator. Some embodiments include a reflector; wherein the FP cavity and the thermistor are integrated on the semiconductor refrigerator. The miniature packaged filter structure is a packaged filter structure with unidirectional input, unidirectional output or single-port bidirectional input and output. By integrating the FP cavity, thermistor, semiconductor refrigerator and other devices in the same miniature package body, high-efficiency optical coupling can be achieved, and the packaged FP cavity is less affected by the external environment; at the same time, the thermistor and the FP cavity are integrated on the semiconductor refrigerator to achieve stable control of the FP cavity temperature. The miniature FP cavity narrowband filter has the comprehensive performance of narrow linewidth, high efficiency, small size, high integration, good reliability and stability.

Description

Technical Field

[0001] The present invention belongs to the field of optical filtering and relates to a miniature FP cavity narrowband filter. Background Art

[0002] Fabry-Perot cavity FP cavity, Fabry-Perot cavity filter is one of the important devices in modern fiber-optic communication and fiber-optic sensing. The FP cavity is generally composed of a glass plate with a high-reflection film on the inner surface and an anti-reflection film on the outer surface. The incident light beam can produce a multi-beam interference effect in the cavity. The light waves that meet the phase matching conditions produce constructive interference to form a filter output; while the light waves that do not meet the phase conditions produce destructive interference and are reflected and output by one side of the FP cavity. By optimizing the parameter design of the FP cavity, a FP cavity narrowband filter with high transmittance and narrow linewidth can be achieved. Compared with other filters based on atomic filtering, coherent filters, grating filtering, etc., the FP cavity filter can achieve the advantages of a wide range of working filter segments, tunable central wavelengths, narrow filter linewidths, and high optical efficiency, and has a wide range of application scenarios.

[0003] However, the existing narrowband filters based on the FP cavity are relatively large in size and have relatively poor corresponding performance. They are easily affected by external environmental factors and have poor reliability and stability. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] The present disclosure provides a micro FP cavity narrowband filter to at least partially solve the above-mentioned technical problems.

[0006] (II) Technical solution

[0007] According to one aspect of the present disclosure, a miniature FP cavity narrowband filter is provided, comprising a miniature packaged filter structure, wherein the miniature packaged filter structure integrates internal devices into the same miniature package body 6 through an optical micromachining process, wherein the internal devices include: an FP cavity 1, which is used to perform narrowband filtering on an input optical signal; a semiconductor refrigerator 3, wherein the FP cavity 1 is integrated on the semiconductor refrigerator 3, wherein the semiconductor refrigerator 3 is used to control the ambient temperature of the FP cavity; and a thermistor 2, which is integrated on the semiconductor refrigerator 3 and is used to collect the ambient temperature of the FP cavity 1.

[0008] In some embodiments of the present disclosure, the micro-packaged filter structure is a unidirectional input and unidirectional output packaged filter structure, and the internal device further includes: a first optical fiber 51, which is partially packaged inside the micro-package 6; a first collimator 41, connected to the first optical fiber 51; a second optical fiber 52, which is partially packaged inside the micro-package 6; and a second collimator 42, connected to the second optical fiber 52;

[0009] Among them, the external optical signal is input to the first collimator 41 through the first optical fiber 51, the first collimator 41 expands the optical signal input by the first optical fiber 51 and transmits it to the FP cavity 1 through free space, the FP cavity 1 performs narrow-band filtering on the optical signal input after the expansion and transmits it through free space, the second collimator 42 receives the optical signal transmitted from the FP cavity 1 after narrow-band filtering, and couples it into the second optical fiber 52 for output.

[0010] In some embodiments of the present disclosure, the micro-packaged filter structure is a single-port bidirectional input and output packaged filter structure, and the internal device further includes: an optical fiber 5, part of which is packaged inside a micro-package 6; a collimator 4, connected to the optical fiber 5; and a reflector 8, which is arranged in the optical path where the FP cavity 1 is located;

[0011] Among them, the external optical signal is input to the collimator 4 through the optical fiber 5. The collimator 4 expands the optical signal input from the optical fiber 5 and transmits it to the FP cavity 1 through free space. The FP cavity 1 performs narrow-band filtering on the optical signal input after the expansion and transmits it to the reflector 8 through free space. The reflector 8 reflects the optical signal after the narrow-band filtering of the FP cavity 1 back to the FP cavity 1 and passes through the FP cavity 1 again for secondary filtering. The optical signal after the secondary filtering is received by the collimator 4 and coupled into the optical fiber 5 for output.

[0012] In some embodiments of the present disclosure, the reflector 8 is coated with a high-reflection film; and / or the reflector 8 is a right-angle prism reflector.

[0013] In some embodiments of the present disclosure, the first collimator 41, the second collimator 42 and the collimator 4 are G-lens fiber collimators; and / or the first optical fiber 51, the second optical fiber 52 and the optical fiber 5 are single-mode optical fibers.

[0014] In some embodiments of the present disclosure, pins 7 are provided on the micro package 6 .

[0015] In some embodiments of the present disclosure, the semiconductor cooler 3 and the thermistor 2 are both connected to the pin 7 on the micro package 6. The working temperature of the FP cavity 1 is adjusted by controlling the semiconductor cooler 3 and the thermistor 2, thereby changing the filtering center wavelength of the micro package filter structure to achieve tuning.

[0016] In some embodiments of the present disclosure, the semiconductor cooler 3 is a semiconductor cooler based on the Peltier effect.

[0017] In some embodiments of the present disclosure, the thermistor 2 is a thermistor with a negative temperature coefficient.

[0018] In some embodiments of the present disclosure, the dimensions of the micro FP cavity narrowband filter are no greater than 4 cm*1.2 cm*0.8 cm.

[0019] (III) Beneficial effects

[0020] It can be seen from the above technical solutions that the micro FP cavity narrowband filter provided by the present disclosure has at least the following beneficial effects:

[0021] 1. Packaged filter structure Since the FP cavity, thermistor, semiconductor cooler and other devices are integrated in the same micro-package through optical micro-machining technology, high-efficiency optical coupling can be achieved, small size, high integration, on this basis, a high-performance FP cavity filter with narrow line width and high efficiency can be realized. Among them, the packaged micro FP cavity is less affected by the external environment. At the same time, the thermistor and FP cavity are integrated on the semiconductor cooler, which can achieve stable control of the FP cavity temperature, further improving the reliability and stability of the micro-packaged filter structure based on the FP cavity, which is not easily affected by the external environment.

[0022] 2. The thermistor and semiconductor cooler inside the micro package can be connected to the outside through pins. The working temperature of the FP cavity can be adjusted by controlling the semiconductor cooler and thermistor, thereby changing the filtering center wavelength of the micro package filter structure, realizing the tuning of the micro FP cavity narrowband filter, which is convenient for integrated control.

[0023] 3. Two miniature packaged filter structures are proposed in the embodiment. The first is a packaged filter structure with unidirectional input and unidirectional output. The miniature FP cavity narrowband filter of this structure can eventually achieve a line width of 10pm and an efficiency better than 70%. Typically, in one example, the miniature FP cavity narrowband filter has an outer dimension of 4cm*1.2cm*0.8cm, a small volume and size, and can be applied to various complex application environments. It has the advantages of small size, high integration, high efficiency and high stability. The second is a packaged filter structure with a single-port bidirectional input and output. The miniature FP cavity narrowband filter of this structure can achieve filtering with a narrower line width, but the efficiency will be reduced to a certain extent. For example, it can eventually achieve a line width of 7pm and an efficiency better than 60%. Typically, in one example, the outer dimension of the miniature FP cavity narrowband filter is 2.5cm*1.2cm*0.8cm, achieving further simplification of size and volume and further narrowing of the line width. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the structure of a micro FP cavity narrowband filter according to the first embodiment of the present disclosure.

[0025] Figure 2 Schematic diagram of the structure of a micro FP cavity narrowband filter according to the second embodiment of the present disclosure.

[0026]

Explanation of symbols

[0027] 1-FP cavity; 2-thermistor;

[0028] 3- semiconductor cooler; 4- collimator;

[0029] 41-a first collimator; 42-a second collimator;

[0030] 51-first optical fiber; 52-second optical fiber;

[0031] 5-optical fiber; 6-micro package;

[0032] 7-pin; 8-reflector. DETAILED DESCRIPTION

[0033] At present, narrowband filters based on FP cavities mostly use discrete device solutions, using optical fibers to expand through collimators, filter through FP cavities, and then output through optical fibers after being coupled through collimators. This type of FP cavity filter based on discrete devices is relatively large in size, resulting in poor performance and low integration. It is also easily affected by external environmental factors, and has poor reliability and stability.

[0034] Therefore, the present application integrates optical fiber, collimator, FP cavity, thermistor, semiconductor refrigerator and other devices into the same micro-package through optical micro-machining technology to form a micro-package filter structure, whose outer dimensions are no more than 4cm*1.2cm*0.8cm, and has the advantages of small size, high integration and strong stability. On this basis, a high-performance FP cavity filter with narrow line width and high efficiency can be realized. Among them, the integration makes the various devices have a closer connection, which is conducive to the optimization of coupling efficiency. The miniaturized setting also makes the thermistor and the semiconductor refrigerator have the advantage of high temperature sensing accuracy, thereby improving the device performance, so that the device can achieve high-efficiency optical coupling, and the packaged micro FP cavity is less affected by the external environment. At the same time, the thermistor and the FP cavity are integrated on the semiconductor refrigerator, which can realize the stable control of the FP cavity temperature, further improving the reliability and stability of the packaged filter structure based on the FP cavity, and having the comprehensive performance of narrow line width, high efficiency, small size, high integration, good reliability and stability.

[0035] The micro FP cavity narrowband filter disclosed in the present invention comprises a micro package filter structure, wherein the micro package filter structure integrates internal devices in the same micro package body through optical micromachining technology, wherein the internal devices comprise: an FP cavity, which is used to perform narrowband filtering on an input optical signal; a semiconductor refrigerator, wherein the FP cavity is integrated on the semiconductor refrigerator, wherein the semiconductor refrigerator is used to control the ambient temperature of the FP cavity; a thermistor, which is integrated on the semiconductor refrigerator, and is used to collect the ambient temperature of the FP cavity; for a package filter structure with unidirectional input and unidirectional output, the internal devices further comprise: an input optical fiber (a first optical fiber), an output optical fiber (a second optical fiber), an input collimator (a first collimator), and an output collimator (a second collimator); and for a package filter structure with a single-port bidirectional input and output, the internal devices further comprise: an optical fiber for input and output, a collimator for input and output, and a reflector for reversing the optical path.

[0036] In some embodiments of the present disclosure, pins are provided on the micro package. Preferably, the semiconductor cooler and the thermistor are both connected to the pins on the package, and the working temperature of the FP cavity is adjusted by controlling the semiconductor cooler and the thermistor, thereby changing the filtering center wavelength of the packaged filter structure to achieve tuning.

[0037] Integrating the internal devices of the micro-package filter structure into the same micro-package can achieve high-efficiency optical coupling, small size and high integration. On this basis, a high-performance FP cavity filter with narrow line width and high efficiency can be realized. Among them, the packaged micro FP cavity is less affected by the external environment. At the same time, the thermistor and FP cavity are integrated on the semiconductor cooler, which can achieve stable control of the FP cavity temperature, further improving the reliability and stability of the packaged filter structure based on the FP cavity.

[0038] In addition, the thermistor and semiconductor cooler inside the package can be connected to the outside through pins. The working temperature of the FP cavity can be adjusted by controlling the semiconductor cooler and thermistor, thereby changing the filtering center wavelength of the packaged filtering structure, and realizing the tuning of the miniature FP cavity narrowband filter, which is convenient for integrated control.

[0039] In some embodiments of the present disclosure, the micro-packaged filter structure is a packaged filter structure with unidirectional input and unidirectional output, such as that shown in the first embodiment.

[0040] In some embodiments of the present disclosure, the micro-packaged filter structure is a single-port bidirectional input-output packaged filter structure, and its input and output ends are the same port, such as shown in the second embodiment.

[0041] In order to make the purpose, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. In the present disclosure, the "external" in the term "external optical signal" is relative to the inside of the micro-package filter structure. The external optical signal is input into the micro-package filter structure through the optical fiber and is called the input optical signal or optical signal. The expressions "input optical signal" and "optical signal" in the optical path are conventional concepts that can be understood by those skilled in the art.

[0042] First embodiment

[0043] In a first exemplary embodiment of the present disclosure, a micro FP cavity narrowband filter is provided.

[0044] Figure 1 Schematic diagram of the structure of a micro FP cavity narrowband filter according to the first embodiment of the present disclosure.

[0045] Reference Figure 1 As shown, the micro FP cavity narrowband filter of this embodiment includes: a micro package filter structure, the micro package filter structure integrates internal devices in the same micro package body 6 through optical micro processing technology, and the micro package body 6 encapsulates the following devices (that is, the internal devices include): FP cavity 1, thermistor 2, semiconductor refrigerator 3, first collimator 41, first optical fiber 51, second collimator 42, and second optical fiber 52. The micro package body 6 is provided with pins 7.

[0046] The packaged filter structure corresponding to this embodiment is a unidirectional input and unidirectional output packaged filter structure, whose input end is connected to the first optical fiber 51, and whose output end is connected to the second optical fiber 52. Parts of the first optical fiber 51 and the second optical fiber 52 are packaged inside the micro package 6, and the remaining parts are located outside the micro package, for receiving external optical signals and transmitting them to the inside of the micro package filter structure.

[0047] The various parts of the micro FP cavity narrowband filter in this embodiment are described in detail below with reference to the accompanying drawings.

[0048] In this embodiment, the FP cavity 1 is integrated on the semiconductor refrigerator 3 and is used to perform narrow-band filtering on the input optical signal; the thermistor 2 is integrated on the semiconductor refrigerator 3 and is used to collect the ambient temperature of the FP cavity 1 .

[0049] In this embodiment, the first collimator 41 is connected to the first optical fiber 51; the second collimator 42 is connected to the second optical fiber 52. The first optical fiber 51 is an input optical fiber, which is used to input the optical signal into the first collimator 41; the second optical fiber 52 is an output optical fiber, which is used to couple the optical signal output from the second collimator 42 to output.

[0050] The first optical fiber 51 is used to input the external optical signal into the first collimator 41 .

[0051] The first collimator 41 is used to expand the optical signal input from the first optical fiber 51 and transmit it through free space.

[0052] The FP cavity 1 is used to perform narrow-band filtering on the optical signal transmitted from the first collimator 41 and then transmit it through free space.

[0053] The second collimator 42 is used to receive the optical signal transmitted from the FP cavity 1 after narrow-band filtering, and couple the optical signal into the second optical fiber 52 .

[0054] The second optical fiber 52 is used to couple out the narrowband filtered optical signal.

[0055] The FP chamber 1 is integrated on a semiconductor refrigerator 3 (TEC), and the TEC 3 is used to control the temperature of the FP chamber 1 .

[0056] The thermistor 2 is integrated on the TEC 3 , and is used to collect the ambient temperature of the FP cavity 1 .

[0057] The micro package 6 is used to install and integrate the first optical fiber (input optical fiber) 51, the second optical fiber (output optical fiber) 52, the TEC 3, the thermistor 2, the FP cavity 1, the first collimator (input collimator) 41 and the second collimator (output collimator) 42, and plays the role of installing, fixing, sealing, protecting the chip and enhancing the electrothermal performance.

[0058] The pin 7 is used to connect the contacts of the integrated chip in the micro package 6 to the package shell through a wire (such as a gold wire). The TEC 3 and the thermistor 2 inside the package can be connected to the outside through the pin 7 to achieve integrated control, which has the advantage of convenient control.

[0059] Reference Figure 1 As shown, an external optical signal (the optical path is not shown in the figure) is input to the first collimator 41 through the first optical fiber 51. The first collimator 41 expands the optical signal input by the first optical fiber 51 and transmits it to the FP cavity 1 through free space. The FP cavity 1 performs narrow-band filtering on the optical signal input after the expansion and transmits it through free space. The second collimator 42 receives the optical signal transmitted from the FP cavity 1 after narrow-band filtering, and couples it into the second optical fiber 52 for output.

[0060] Among them, the semiconductor cooler 3 and the thermistor 2 are both connected to the pin 7 on the micro package 6. The working temperature of the FP cavity 1 is adjusted by controlling the semiconductor cooler 3 and the thermistor 2, thereby changing the filtering center wavelength of the micro package filter structure to achieve tuning.

[0061] Preferably, the semiconductor refrigerator 3 is a semiconductor refrigerator based on the Peltier effect.

[0062] Preferably, the thermistor 2 is a thermistor with a negative temperature coefficient.

[0063] Typically, the optical signal can operate in the 1550 nm band, and the input optical fiber can be, but is not limited to, a 1550 nm single-mode optical fiber. Typically, the first collimator 41 and the second collimator 42 can be, but are not limited to, planar (G-lens) optical fiber collimators.

[0064] In this embodiment, the micro-packaged filter structure integrates and packages internal components such as the FP cavity 1, thermistor 2, semiconductor refrigerator 3, first collimator 41, first optical fiber 51, second collimator 42, and second optical fiber 52 in a micro-package body 6 through optical micromachining technology.

[0065] In one example, the optimization setting process of the micro FP cavity narrowband filter is as follows: for a single FP cavity, by optimizing the parameter design of the FP cavity, a FP cavity product with a transmittance greater than 90% and a line width of about 10pm can be achieved in the 1550nm band, and the optimized setting is used as the setting of the FP cavity in the micro FP cavity narrowband filter; by optimizing the parameters of the first optical fiber, the first collimator, the second collimator and the second optical fiber through optical micromachining technology, a coupling efficiency better than 80% can be achieved. On the basis of the above first two optimizations, by integrating the performance-optimized FP cavity with TEC, integrating the thermistor with TEC, and forming a filtering optical path with the optical fiber and the collimator, a high-performance FP cavity narrowband filter with a line width of about 10pm and an efficiency better than 70% (90%×80%=72%) can be finally achieved. Typically, the micro FP cavity narrowband filter has an outer dimension of 4cm*1.2cm*0.8cm, with a small volume and size, and can be applied to various complex application environments.

[0066] The micro FP cavity narrowband filter of this embodiment has the advantages of small size, high integration, high efficiency and high stability.

[0067] Second embodiment

[0068] In a second exemplary embodiment of the present disclosure, a micro FP cavity narrowband filter is provided.

[0069] Figure 2 Schematic diagram of the structure of a micro FP cavity narrowband filter according to the second embodiment of the present disclosure.

[0070] Reference Figure 2As shown, the micro FP cavity narrowband filter of this embodiment is the same as the first embodiment in other parts, and the difference is that the micro package filter structure of this embodiment is a single-port bidirectional input and output package filter structure, and its input and output ends are the same port.

[0071] Specifically, the micro FP cavity narrowband filter of this embodiment includes: a micro package filter structure, the micro package filter structure integrates internal devices in the same micro package body 6 through optical micro processing technology, and the micro package body 6 encapsulates the following devices (that is, the internal devices include): FP cavity 1, thermistor 2, semiconductor refrigerator 3, collimator 4, optical fiber 5, and reflector 8. The micro package body 6 is provided with pins 7.

[0072] The functions, configurations, and specific component forms of the thermistor 2, semiconductor cooler 3, micro package 6, and pin 7 are substantially the same as those of the first embodiment and will not be described in detail here. Other components are described in detail as follows.

[0073] In this embodiment, the collimator 4 and the optical fiber 5 are used as input and output ports at the same time. The optical fiber 5 is used to input the external optical signal into the collimator 4 (input path) or to output the optical signal after narrow-band filtering (output path); the collimator 4 is used to expand the optical signal input by the optical fiber 5 and transmit it through free space (input path) or to receive the optical signal transmitted by the FP cavity 1 after narrow-band filtering (secondary filtering) (output path), and couple it into the optical fiber 5 for output.

[0074] In this embodiment, the reflector 8 is used to reflect the optical signal after narrow-band filtering through the FP cavity 1 back to the FP cavity to pass through the FP cavity 1 again for secondary filtering.

[0075] Preferably, the reflector 8 is a reflector product with high reflectivity, for example, the reflector 8 is coated with a high reflective film; and / or, the reflector 8 is a right-angle prism reflector.

[0076] Typically, the optical fiber 5 may be, but is not limited to, a single-mode optical fiber of 1550 nm. Typically, the collimator 4 may be, but is not limited to, a planar (G-lens) optical fiber collimator.

[0077] Reference Figure 2 As shown, the external optical signal is input to the collimator 4 through the optical fiber 5. The collimator 4 expands the optical signal input from the optical fiber 5 and transmits it to the FP cavity 1 through the free space. The FP cavity 1 performs narrow-band filtering on the optical signal input after the expansion and transmits it to the reflector 8 through the free space. The reflector 8 reflects the optical signal after the narrow-band filtering of the FP cavity 1 back to the FP cavity 1 and passes through the FP cavity 1 again for secondary filtering. The optical signal after the secondary filtering is received by the collimator 4 and coupled into the optical fiber 5 for output.

[0078] In some embodiments of the present disclosure, the reflector 8 is a right-angle prism reflector; the reflector 8 is coated with a high-reflection film.

[0079] In one example, the optimization setting process of the micro FP cavity narrowband filter is as follows: for a single FP cavity, by optimizing the parameter design of the FP cavity, a FP cavity product with a transmittance greater than 90% and a line width of about 10pm can be achieved in the 1550nm band. By optimizing the parameters of the optical fiber and the collimator through optical micromachining technology, a coupling efficiency better than 80% can be achieved. Since the optical signal passes through the FP cavity twice, the actual transmittance is better than 80% and the line width is about 7pm. On the basis of the first two optimizations mentioned above, by integrating the performance-optimized FP cavity with TEC, integrating the thermistor with TEC, and forming a filtering optical path with the optical fiber and the collimator, a high-performance FP cavity narrowband filter with a line width of about 7pm and an efficiency better than 60% (90%×90%×80%=64%) can be finally achieved. Typically, the micro FP cavity narrowband filter has an outer dimension of 2.5cm*1.2cm*0.8cm, which is small in volume and size and can be applied to various complex application environments.

[0080] Compared with the first embodiment, in the micro FP cavity narrow-band filter of the second embodiment, the optical signal passes through the FP cavity twice, which can achieve filtering with a narrower line width. At the same time, since the same optical fiber and collimator are used for input and output, the volume and size of the micro FP cavity narrow-band filter can be further simplified, that is, the size and volume can be further simplified and the line width can be further narrowed, but the efficiency will be reduced to a certain extent.

[0081] In summary, the present disclosure provides a micro FP cavity narrowband filter, which integrates the FP cavity, thermistor, semiconductor refrigerator, collimator, optical fiber and other devices in the same micro package through, for example, optical micromachining technology, and can achieve high-efficiency optical coupling, small size, and high integration. On this basis, a high-performance FP cavity filter with narrow line width and high efficiency can be realized. Among them, the packaged micro FP cavity is less affected by the external environment, and at the same time, the thermistor and the FP cavity are integrated on the semiconductor refrigerator, which can achieve stable control of the FP cavity temperature, further improving the reliability and stability of the micro package filter structure based on the FP cavity, which is not easily affected by the external environment, and has the comprehensive performance of narrow line width, high efficiency, small size, high integration, good reliability and stability.

[0082] Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure. The shapes and sizes of the components in the drawings do not reflect the actual size and proportion, but only illustrate the contents of the embodiments of the present disclosure. In addition, in the claims, any reference symbol between brackets should not be constructed as a limitation to the claims.

[0083] In addition, to achieve the purpose of neatness of the drawings, some conventional structures and components may be depicted in a simple schematic manner in the drawings. In addition, some features in the drawings of the present case may be slightly enlarged or their proportions or sizes may be changed to facilitate the understanding and viewing of the technical features of the present disclosure, but this is not used to limit the present disclosure. The actual size and specifications of the products manufactured according to the contents of the present disclosure should be adjusted according to the needs of production, the characteristics of the product itself, and the contents of the present disclosure, which is stated in advance.

[0084] Unless otherwise indicated, the numerical parameters in this specification and the appended claims are approximate values ​​and can vary according to the desired properties obtained through the content of the present disclosure. Specifically, all numbers used in the specification and claims to express the content of the composition, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. In general, the meaning of the expression is to include a variation of ±10% in some embodiments, ±5% in some embodiments, ±1% in some embodiments, and ±0.5% in some embodiments by a specific number.

[0085] The ordinal numbers used in the specification and claims, such as "first", "second", "third", etc., to modify the corresponding elements, do not themselves mean that the elements have any ordinal numbers, nor do they represent the order of one element and another element, or the order in the manufacturing method. The use of these ordinal numbers is only used to clearly distinguish a component with a certain name from another component with the same name.

[0086] Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0087] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A miniature FP cavity narrowband filter, characterized in that: The invention comprises a micro-package filter structure, wherein the micro-package filter structure integrates internal devices in the same micro-package body (6) through an optical micro-machining process, wherein the internal devices include: An FP cavity (1) is used to perform narrow-band filtering on an input optical signal; the FP cavity is composed of a glass plate with a high-reflection film on the inner surface and an anti-reflection film on the outer surface; A semiconductor refrigerator (3), the FP cavity (1) being integrated on the semiconductor refrigerator (3), and the semiconductor refrigerator (3) being used to control the ambient temperature of the FP cavity (1); A thermistor (2) is integrated on the semiconductor cooler (3) and is used to collect the ambient temperature of the FP cavity (1); Wherein, the micro package (6) is provided with pins (7); The semiconductor cooler (3) and the thermistor (2) are both connected to the pins (7) on the micro-package (6); the operating temperature of the FP cavity (1) is adjusted by controlling the semiconductor cooler (3) and the thermistor (2), thereby changing the filtering center wavelength of the micro-package filtering structure and achieving tuning; The micro-packaged filter structure is a single-port bidirectional input-output packaged filter structure, and the internal components further include: an optical fiber (5), part of which is packaged inside the micro-package (6); a collimator (4), connected to the optical fiber (5); and a reflector (8), arranged in the optical path where the FP cavity (1) is located; An external optical signal is input to the collimator (4) through the optical fiber (5); the collimator (4) expands the optical signal input by the optical fiber (5) and transmits it to the FP cavity (1) through free space; the FP cavity (1) performs narrow-band filtering on the optical signal input after the expansion and transmits it to the reflector (8) through free space; the reflector (8) reflects the optical signal after the narrow-band filtering by the FP cavity (1) back to the FP cavity (1) and passes through the FP cavity (1) again for secondary filtering; the optical signal after the secondary filtering is received by the collimator (4) and coupled into the optical fiber (5) for output.

2. The miniature FP cavity narrowband filter according to claim 1, characterized in that: The reflector (8) is coated with a high-reflection film; and / or, The reflector (8) is a right-angle prism reflector.

3. The miniature FP cavity narrowband filter according to claim 1, characterized in that: The collimator (4) is a planar optical fiber collimator; and / or, The optical fiber (5) is a single-mode optical fiber.

4. The miniature FP cavity narrowband filter according to claim 1, characterized in that: The semiconductor refrigerator (3) is a semiconductor refrigerator based on the Peltier effect.

5. The miniature FP cavity narrowband filter according to claim 1, characterized in that: The thermistor (2) is a thermistor with a negative temperature coefficient.

6. The miniature FP cavity narrowband filter according to claim 1, characterized in that: The outer dimensions of the miniature FP cavity narrowband filter are no greater than 4 cm*1.2 cm*0.8 cm.

7. A miniature FP cavity narrowband filter, characterized in that: The invention comprises a micro-package filter structure, wherein the micro-package filter structure integrates internal devices in the same micro-package body (6) through an optical micro-machining process, wherein the internal devices include: An FP cavity (1) is used to perform narrow-band filtering on an input optical signal; the FP cavity is composed of a glass plate with a high-reflection film on the inner surface and an anti-reflection film on the outer surface; A semiconductor refrigerator (3), the FP cavity (1) being integrated on the semiconductor refrigerator (3), and the semiconductor refrigerator (3) being used to control the ambient temperature of the FP cavity (1); A thermistor (2) is integrated on the semiconductor cooler (3) and is used to collect the ambient temperature of the FP cavity (1); Wherein, the micro package (6) is provided with pins (7); The semiconductor cooler (3) and the thermistor (2) are both connected to the pins (7) on the micro-package (6); the operating temperature of the FP cavity (1) is adjusted by controlling the semiconductor cooler (3) and the thermistor (2), thereby changing the filtering center wavelength of the micro-package filtering structure and achieving tuning; The micro-packaged filter structure is a unidirectional input and unidirectional output packaged filter structure, and the internal device further comprises: a first optical fiber (51), part of which is packaged inside the micro-package (6); a first collimator (41), connected to the first optical fiber (51); a second optical fiber (52), part of which is packaged inside the micro-package (6); and a second collimator (42), connected to the second optical fiber (52); An external optical signal is input to the first collimator (41) through the first optical fiber (51); the first collimator (41) expands the optical signal input by the first optical fiber (51) and transmits it to the FP cavity (1) through free space; the FP cavity (1) performs narrow-band filtering on the optical signal input after the expansion and transmits it through free space; the second collimator (42) receives the optical signal transmitted by the FP cavity (1) after the narrow-band filtering and couples it into the second optical fiber (52) for output.

8. The miniature FP cavity narrowband filter according to claim 7, characterized in that: The first collimator (41) and the second collimator (42) are planar optical fiber collimators; and / or, The first optical fiber (51) and the second optical fiber (52) are single-mode optical fibers.

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