Implementation method of a micro spectrometer module based on a metal microcavity array

Abstract

The present invention provides a method for implementing a micro spectrometer module based on a metal microcavity array, so as to improve its spectral resolution and reduce the process complexity of the preparation method of the intracavity dielectric layer in the microcavity array; the micro spectrometer module includes a microcavity array with a Fabry-Perot structure having a metal thin film as a reflective layer and a detector array; the method for improving spectral resolution includes a method for obtaining a spectrum by based on preset calibration information of quasi-monochromatic light and spectral reconstruction, and increasing the number of microcavity units in the microcavity array; the preparation method of the intracavity dielectric layer in the microcavity array is to obtain intracavity dielectric layers with a large number of different thicknesses through fewer process steps, so as to implement a microcavity array with a large number of microcavity units.

Description

Technical Field

[0001] The present invention relates to a micro spectrometer module, and in particular to a method for implementing a micro spectrometer module based on a metal microcavity array. Background Art

[0002] A spectrometer is a very important optical instrument. The core of the working principle of a spectrometer lies in its spectral splitting technology. Currently, common spectrometers generally fall into two categories: one is the dispersive spectral splitting type represented by a grating spectrometer; the other is the modulation type represented by a Fourier transform spectrometer based on an interferometer. Professional spectrometers at the laboratory level are generally large in size and expensive in price, and their overall performance often weakens as the instrument size shrinks.

[0003] In recent years, with the development of information technology, the intelligentization of production and life, and the growing demands of people for food safety, environmental pollution, medical health, etc., micro spectrometer modules have received attention. Their application targets are developing towards being used as sensing components of intelligent devices and consumer electronic products (such as smart phones and wearable devices, etc.).

[0004] Among them, implementing a micro spectrometer module based on a filter array structure is an important approach. This kind of micro spectrometer module irradiates the transmitted light passing through each filter unit in the filter array onto the corresponding detector unit in the detector array for photoelectric conversion, and then obtains the spectrum through subsequent data processing. According to the different structures of its filter array, examples are as follows:

[0005] For example, the filter array is based on a vertical Fabry-Perot resonator (hereinafter referred to as F-P cavity) array structure with different cavity lengths. Since its background art is comparable to that of the present invention, it will be specifically described later.

[0006] For example, the filter array is based on a photonic crystal structure of a dielectric material [as involved in the following documents: 1. N.K. Pervez, W. Cheng, et al., Opt. Express, 18(8), 8277(2010); 2. X. Gan, et al., Appl. Phys. Lett., 100, 231104(2012); etc.];

[0007] In addition, for example, the filter array structure is based on metal micro-nano structures [as involved in the following published invention patents: Chinese invention patents CN 105092035B, CN 109642822A, CN 110873911 A, CN 110243471 A, CN109564323A, etc.; US invention patents US 8542359 B2, US 7426040 B2, etc.].

[0008] The Fabry-Perot resonator structure described above is a common and very important resonator structure that can achieve the function of filtering light. For the application of a filter array based on the Fabry-Perot resonator structure in a micro spectrometer module, if a relatively wide working wavelength range and high spectral resolution are desired, according to its basic theory, this resonator structure needs to have a very high finesse. For example, the cavity length of the resonator should be small, and the reflectivity of the two end mirrors should be very high, which is generally difficult to achieve. The following is a brief introduction taking the relevant reports in several documents and the situations in the disclosed patents as examples:

[0009] For example, in the F-P cavity filter array reported by simulation in the literature [Wen Zhiyu, Chen Gang, Wang Jianguo, Spectroscopy and Spectral Analysis, 26(10), 1955(2006)], the upper and lower mirrors of the F-P cavity in each unit are both metals. To obtain a narrow band, it is necessary to increase the cavity length and utilize its high-order resonance mode, but this reduces the working wavelength range of the filter array. At the same time, it is relatively difficult to fabricate an F-P cavity array with different cavity lengths based on mass-production planar processes. For example, N array units are fabricated through N repeated process flows; when N is several hundred, at least thousands of processes are required only for the cavity medium fabrication process.

[0010] For example, in the filter array reported in the literature [S.W. Wang, et al., Opt. Lett., 31(3), 332(2006)], the upper and lower mirrors of the F-P cavity are distributed Bragg reflectors (DBRs) based on multi-layer dielectric films. The high reflectivity of the DBR mirror enables each filter unit to have a relatively narrow transmission passband, but the high reflectivity of the DBR mirror only exists within a certain limited wavelength range. Therefore, the working range of the micro spectrometer module based on this F-P cavity structure is small. At the same time, the processes for fabricating the DBR mirror and the cavity dielectric films with different thicknesses in different array units are relatively complex.

[0011] For example, in the literature [A. Emadi, et al., Opt. Express, 20(1), 489(2011)] and the Chinese invention patent [CN110873605A], a linear variable filter (LVF) based on the F-P cavity structure with continuously varying cavity length is utilized. The upper and lower mirrors of the F-P cavity are metal or DBR dielectric mirrors. The fabrication process of the dielectric layer with continuously varying thickness is also incompatible with planar processes and has poor reproducibility. Due to the continuously varying cavity length, there is no clear unit boundary, and the stray light crosstalk between different wavelengths is large. Moreover, there is also the restrictive relationship between spectral resolution and working wavelength range as described above.

[0012] In addition, in Chinese invention patents [CN 110243471 A, CN 108731806 A], one or both of the mirrors in the F-P cavity are mirrors based on metal micro-nano structures on their surfaces. Such mirrors based on metal micro-nano structures have a relatively high reflectivity within a certain wavelength band (but not extremely high), so the metal micro-nano structures in different filter units need to have different structural parameters. The preparation process of such micro-nano structures has very high requirements. Summary of the Invention

[0013] The present invention provides a method for implementing a micro-spectrometer module based on a metal microcavity array to improve its spectral resolution and reduce the process complexity of the preparation method of the intracavity dielectric layer in the microcavity array.

[0014] The method for improving spectral resolution includes a method for obtaining a spectrum by pre-setting calibration information and spectral reconstruction based on quasi-monochromatic light, and increasing the number of microcavity units in the microcavity array.

[0015] The preparation method of the intracavity dielectric layer in the microcavity array is to obtain intracavity dielectric layers with a large number of different thicknesses through a smaller number of process steps, thereby realizing a microcavity array with a large number of microcavity units. Having a large number of microcavity units is beneficial to improving the spectral resolution and working wavelength range of the micro-spectrometer module.

[0016] The micro-spectrometer module described in the embodiments of the present invention at least includes a microcavity array and a detector array, and may also include a signal light collection and beam shaping optical path, a signal processing and control circuit, and a module structural member, etc.

[0017] The microcavity array is composed of a plurality of microcavity units. The microcavity unit has a Fabry-Perot-like resonant cavity structure, that is, it includes a first reflective layer metal film, a second reflective layer metal film, and an intracavity dielectric layer. The reflective layer metal film is an ultra-thin metal film with partial reflection and partial transmission optical characteristics. The intracavity dielectric layer is a light-transmitting dielectric material film.

[0018] Each microcavity unit in the microcavity array has a different intracavity dielectric layer thickness; adjacent microcavity units are connected to each other or isolated from each other; each microcavity unit has a regular or irregular shape in the plane of the microcavity array and is arranged in a regular or irregular manner.

[0019] The detector array is composed of its inherent multiple detector unit pixels. The detector array can be planned to have multiple detector units, and each detector unit includes one or more detector unit pixels.

[0020] Each microcavity unit in the described microcavity array corresponds to each detector unit in the detector array respectively.

[0021] Before the described micro-spectrometer module is used after manufacturing and packaging, it is necessary to first perform a preset calibration test on it to obtain the digital electrical signals generated by the optical responses of quasi-monochromatic lights of different wavelengths on the detector array after being received by the micro-spectrometer module; in the spectral test of the signal light from the target object, obtain the digital electrical signals generated by the optical responses of the signal light from the target object on the detector array of the micro-spectrometer module; finally, combine the preset calibration information and the test information of the signal light, and perform spectral reconstruction through data processing calculation to obtain the spectrum of the measured signal light.

[0022] The spectral test system of the micro-spectrometer module in the embodiment of the present invention includes: the described micro-spectrometer module, as well as a signal processing system, a control system, an input / output terminal, etc. that match it.

[0023] The preset calibration test system of the micro-spectrometer module in the embodiment of the present invention includes: a calibration light source and the spectral test system of the described micro-spectrometer module.

[0024] The calibration light source is a quasi-monochromatic light source with adjustable wavelength, that is, it can provide quasi-monochromatic light with adjustable wavelength and stable output power within the working wavelength range of the micro-spectrometer module. The quasi-monochromatic light has a narrow spectral line width and a small adjustable wavelength interval, and its wavelength positions are relatively evenly distributed within the working wavelength range of the micro-spectrometer module.

[0025] In the preset calibration test of the micro-spectrometer module, the quasi-monochromatic lights with different wavelengths output by the calibration light source are respectively input into the micro-spectrometer module, and the signal processing system records the digital electrical signals generated by the detector array in the micro-spectrometer module to characterize the light signal intensities received by each detector unit.

[0026] The above-mentioned preset calibration information includes: the output powers of the quasi-monochromatic lights with different wavelengths corresponding to the calibration light source, the intensities of the lights characterized by the digital electrical signals received by the signal processing system from various detector units and other components, and other relevant information. This preset calibration information uniquely corresponds to the specific micro-spectrometer module to be calibrated. This preset calibration information needs to be saved for calling in the spectral reconstruction calculation when using this micro-spectrometer module for spectral testing.

[0027] The highest spectral resolution that the micro-spectrometer module can achieve based on the method of the present invention depends on its own hardware system, and also depends on the spectral line widths and wavelength intervals of the quasi-monochromatic lights output by the calibration light source, as well as the spectral reconstruction algorithm.

[0028] In the method for preparing the intracavity dielectric layer in the microcavity array according to the embodiment of the present invention, after the deposition of the first reflective layer metal thin film of each microcavity unit in the microcavity array, the thin film deposition process (such as electron beam evaporation, thermal evaporation, magnetron sputtering, or chemical vapor deposition method, etc.) is used fewer times to separately prepare thin films of intracavity dielectric layer materials with different specific thicknesses in the regions of specific different microcavity units in the microcavity array, forming intracavity dielectric layers with a large number of different thicknesses, and then the deposition of the second reflective layer metal thin film of each microcavity unit in the microcavity array is carried out. As described in the two embodiments proposed in the specific implementation manner of the present invention: through N times of coating, up to (2 N - 1) intracavity dielectric layers with different thicknesses can be formed; or through (M + N) times of coating, up to M×(N + 1) intracavity dielectric layers with different thicknesses can be formed.

[0029] Another embodiment of the method for preparing the intracavity dielectric layer in the microcavity array proposed by the present invention is that after the deposition of the first reflective layer metal thin film of each microcavity unit in the microcavity array, many randomly distributed discrete dielectric flakes with randomly varying thicknesses in the micro-nano scale are scattered on the first reflective layer metal thin film, and then the deposition of the second reflective layer metal thin film of each microcavity unit in the microcavity array is carried out.

[0030] Some of the main features, innovative points, and advantages of the present invention are described as follows:

[0031] In the embodiment of the present invention, the reflective layer in the Fabry - Perot - like metal microcavity uses a metal thin film, enabling the micro - spectrometer module to have a very wide working band and being unrestricted within the wavelength range from ultraviolet to infrared light.

[0032] The adverse effects brought about by using a metal thin film as the reflective layer in the metal microcavity (such as the reduction of the resonance quality factor and the impact on the spectral resolution) are overcome and compensated to a certain extent by the benefits of the method for pre - calibrating and spectral reconstruction of the micro - spectrometer module described in the present invention.

[0033] Applied in the Fabry - Perot metal - like microcavity of a spectrometer module, when the thickness of the dielectric layer in the cavity is different, the resonant mode in the cavity can be the fundamental mode or the high - order mode. The transmission passband corresponding to the fundamental mode is relatively wide, enabling the spectrometer module to have a relatively wide working wavelength range, but its spectral resolution is relatively low; the transmission passband corresponding to the high - order mode is relatively narrow, enabling the spectrometer module to have a relatively high spectral resolution, but its working wavelength range is relatively small. Conventionally, to obtain a high spectral resolution, a high - order resonant mode with a narrow passband bandwidth is generally adopted, and its working wavelength range is small. The method for obtaining a spectrum through preset calibration and spectral reconstruction in the micro - spectrometer module described in the embodiments of the present invention breaks through the restrictive relationship between the spectral resolution and the working wavelength range when using low - order or high - order resonant modes in the metal microcavity. Therefore, the metal microcavity described in the embodiments of the present invention can be based on the resonant modes of the fundamental mode or (and) the high - order mode to simultaneously achieve a large working wavelength range and a high spectral resolution. Among them, although the performance of the metal microcavity still has an important impact on the spectral resolution, it is not decisive; the highest spectral resolution that can be achieved by the micro - spectrometer module based on the method described in the present invention will largely depend on the spectral linewidth and wavelength interval of each quasi - monochromatic light output by the calibration light source during its preset calibration, as well as the spectral reconstruction algorithm.

[0034] Meanwhile, based on the method for obtaining a spectrum through preset calibration and spectral reconstruction described in the embodiments of the present invention, the micro - cavity units with different resonant characteristics in the micro - cavity array can be randomly distributed in the micro - cavity array, and even each micro - cavity unit in the micro - cavity array can be arranged in an irregular manner. In this way, the tolerance of the manufacturing process of the micro - cavity array is enhanced.

[0035] The method for preparing the dielectric layer in the cavity of the micro - cavity array described in the embodiments of the present invention makes the process of preparing a micro - cavity array with a large number of micro - cavity units simple and feasible, reducing the process cost. And a micro - cavity array with a large number of micro - cavity units enables the micro - spectrometer module to obtain a large number of parameter information during preset calibration and spectral reconstruction, which is conducive to improving its spectral resolution and also conducive to expanding its working wavelength range.

[0036] The preset calibration in the embodiments of the present invention is carried out after the micro - spectrometer module is manufactured and packaged. The obtained preset calibration information implicitly includes the comprehensive influence of the optical response and photoelectric conversion factors of each part and component inside the corresponding micro - spectrometer module, the structural deviation during the manufacturing process and the alignment deviation between each part, as well as other uncontrollable and unclear factors on the spectral test. Description of the Drawings

[0037] Figure 1 is a schematic cross - sectional structure diagram of an exemplary micro - spectrometer module according to an embodiment of the present invention.

[0038] Figure 2 It is a schematic side view of the microcavity array and the detector array in the micro spectrometer module according to an embodiment of the present invention.

[0039] Figure 3 It is a schematic cross-sectional view of the microcavity array in the micro spectrometer module according to an embodiment of the present invention. Among them, in (a), adjacent microcavity units are connected to each other; in (b), adjacent microcavity units are isolated from each other.

[0040] Figure 4 It is a schematic plan view of exemplary shapes and arrangement manners of microcavity units in the microcavity array in the micro spectrometer module according to an embodiment of the present invention. Among them, in (a), the interconnected microcavity units have regular shapes and are arranged in a periodic and regular manner; in (b), the isolated microcavity units have regular shapes and are arranged in a periodic and regular manner; in (c), the interconnected microcavity units have irregular shapes and are arranged in an irregular manner; in (d), the isolated microcavity units have irregular shapes and are arranged in an irregular manner.

[0041] Figure 5 It is a schematic view of the transmission spectra of the respective microcavity units in the microcavity array in the micro spectrometer module according to an embodiment of the present invention.

[0042] Figure 6 It is a schematic plan view of the microcavity array and its microcavity units in the micro spectrometer module according to an embodiment of the present invention.

[0043] Figure 7 It is a schematic plan view of the detector array, its detector unit pixels, and the planned detector units in the micro spectrometer module according to an embodiment of the present invention. In the figure, the thin-line small grids represent the detector unit pixels, and the thick-line large grids represent the detector units corresponding to the respective microcavity units in the microcavity array, which are composed of several detector unit pixels.

[0044] Figure 8 It is a schematic view of the micro spectrometer module according to an embodiment of the present invention for spectral testing of the signal light.

[0045] Figure 9 It is a schematic view of the micro spectrometer module according to an embodiment of the present invention for performing pre-calibration testing.

[0046] Figure 10 It is a schematic view of the normalized spectral curves (a) of the respective quasi-monochromatic lights and the distribution curves (b) of the electrical signal intensities generated by the respective quasi-monochromatic lights on the respective detector units in the detector array during pre-calibration in the micro spectrometer module according to an embodiment of the present invention.

[0047] Figure 11 It is a schematic diagram of the preparation method of the intracavity dielectric layers with different thicknesses in each microcavity unit of the microcavity array in the micro-spectrometer module according to an embodiment of the present invention. Example: As shown in (a) to (e), dielectric thin films with 5 different thicknesses (identified by a, b, c, d, e) are successively prepared in the regions of specific different microcavity units, and finally, the intracavity dielectric layers in each of the 31 different microcavity units as shown in (f) are formed. The thickness of the intracavity dielectric layer in the microcavity unit with different thickness markings in (f) is the superposition of these thicknesses. The shaded areas in the figure are the areas that are reserved each time without dielectric thin film deposition.

[0048] Figure 12 It is a schematic diagram of the preparation method of the intracavity dielectric layers with different thicknesses in each microcavity unit of the microcavity array in the micro-spectrometer module according to an embodiment of the present invention. Example: As shown in (a), dielectric thin films with 6 different thicknesses (the step size of thickness change is Δa) are prepared in the regions of different partial microcavity units in a certain direction, and then dielectric thin films with 4 different thicknesses (the step size of thickness change is Δb) are prepared in the regions of different partial microcavity units along another direction, and finally, the intracavity dielectric layers in each of the 30 different microcavity units as shown in (b) are formed. Detailed implementation manners

[0049] To describe in detail the technical content, structural features, achieved objectives and effects of the present invention, the following is a detailed description in combination with the implementation manners and accompanied by the drawings.

[0050] The following embodiments are exemplary embodiments, which may have different forms or variations and should not be construed as being limited to the descriptions given here. In the description of the embodiments of the present invention, expressions such as "on..." may include "on... in a non-contact manner" and "directly on... in a contact manner"; expressions such as "under..." may include "under... in a non-contact manner" and "directly under... in a contact manner"; expressions such as "between... and (with)..." mean "between... and... in a contact or non-contact manner"; expressions such as "including..." mean "including but not limited to only..."; expressions such as "after..." in the sequence of performing different actions mean "after... but not limited to immediately following", and there may be other implementation actions in between; the expression of "wavelength" for quasi-monochromatic light means the "central wavelength or peak wavelength" of the quasi-monochromatic light.

[0051] Figure 1 A micro-spectrometer module according to an embodiment of the present invention is shown, including: a microcavity array 100, a detector array 200, and a signal light collection and beam shaping optical path 300.

[0052] Among them, the signal light collection and beam shaping optical path 300 includes a diffuser 310, a diaphragm 320, and a lens 330, and may also include other beneficial optical elements. The purpose of this part is to collect the signal light uniformly and efficiently and make it into parallel collimated light to vertically irradiate the filter array.

[0053] Figure 1 Among the microcavity array 100, the detector array 200, the signal light collection and beam shaping optical path 300 shown in the figure, and related components such as the diffuser 310, the diaphragm 320, and the lens 330 therein, they can be combined together separately with a certain support structure, or stacked together in contact with some transparent media as intermediate media. The described micro spectrometer module can be a single component or a part integrated into other optoelectronic devices or systems.

[0054] Figure 2 is a schematic side view structure of the microcavity array 100 and the detector array 200 in the micro spectrometer module according to an embodiment of the present invention. As shown in the figure: the microcavity array 100 is composed of J microcavity units 110; the detector array 200 is composed of J detector units 210; each detector unit 210 (such as R1, R2,..., R j ,...) in the detector array 200 respectively corresponds to and is aligned with each microcavity unit 110 (such as D1, D2,..., D j ) in the microcavity array 100.

[0055] Figure 3 is a schematic cross-sectional structure of the microcavity array 100 in the micro spectrometer module according to an embodiment of the present invention. The microcavity units 110 (R1, R2,..., R j ,...) in the microcavity array 100 include: a substrate 111, a first reflective layer metal thin film 112, a second reflective layer metal thin film 113, and an intracavity dielectric layer 114.

[0056] Among them, the substrate 111 can be a transparent medium with a thickness of dozens of micrometers to several millimeters, or a transparent medium with a thickness of dozens of nanometers to hundreds of micrometers located above the detector array 200.

[0057] The first reflective layer metal thin film 112 and the second reflective layer metal thin film 113 are ultra-thin metal thin films with the optical characteristics of partial reflection and partial transmission, and the thickness (t m1 , t m2 ) is about 5 - 100 nm ultra-thin metal thin film, and good conductor metals such as gold, silver, aluminum, copper, etc. can be preferably used.

[0058] The material of the intracavity dielectric layer 114 is a transparent medium, and its thickness (t d)It is determined by the refractive index of the intracavity dielectric layer material, parameters such as the resonant mode, resonant characteristics, and resonant quality factor in the microcavity unit 110, as well as the selection and design of the working wavelength range of the micro-spectrometer module. For example, in the ultraviolet to near-infrared wavelength range, the thickness of the intracavity dielectric layer 114 with a refractive index of about 1.5 to 2.5 can be selected in the range of approximately 10 nm to 100 μm. The thicknesses of the intracavity dielectric layers 114 in different microcavity units 110 in the microcavity array 100 should be different; if they are the same, they can be regarded as an equivalent microcavity unit 110, or the effects generated by some of the microcavity units 110 are regarded as invalid. In addition, the distribution of the intracavity dielectric layers 114 with different thicknesses in the microcavity array 100 in each microcavity unit 110 can be regular or irregular.

[0059] Figure 3 In the exemplary example shown in (a), adjacent microcavity units 110 are connected to each other. Figure 3 In the exemplary example shown in (b), adjacent microcavity units 110 are isolated from each other. For Figure 3 For the microcavity array 100 shown in (b), after depositing and preparing the first reflective layer metal film 112, the isolated intracavity dielectric layers 114 in each microcavity unit 110 are prepared on it, and then the continuous second reflective layer metal film 113 is deposited and prepared, so that an isolation region 120 with a thicker metal film layer is naturally formed between each microcavity unit 110. Figure 3 The structure shown in (b) is beneficial to reducing the stray light crosstalk between adjacent but non-corresponding microcavity units 110 and detector units 210.

[0060] Figure 4 Shows the characteristics of the shape and arrangement of the microcavity units 110 in the microcavity array 100 in the micro-spectrometer module according to an embodiment of the present invention. The figure shows that: the microcavity units 110 in the microcavity array 100 can be connected to each other or isolated from each other; the microcavity units 110 in the microcavity array 100 can be arranged in a regular manner or in an irregular manner; the microcavity units 110 in the microcavity array 100 can have regular shapes (such as square, circular, polygonal, etc.) or irregular shapes; or a situation combining several of the above-mentioned characteristics.

[0061] Figure 5 Is a schematic diagram of the transmission spectrum of each microcavity unit 110 in the microcavity array 100 in the micro-spectrometer module according to an embodiment of the present invention. The figure shows that, relative to the position numbering order of each microcavity unit 110 in the microcavity array 100 (such as R1, R2, R3,..., R j, …), the transmission spectra of the respective microcavity units are characterized by disordered arrangement, that is, the positions of the characteristic wavelengths (such as the spectral peak wavelengths) of their transmission spectra do not monotonically redshift or blueshift as the serial number of the microcavity unit 110 increases. That is to say, the thickness distributions of the different intracavity dielectric layers 114 in the different microcavity units 110 are disordered. Of course, the microcavity array 100 with the structural characteristics of the microcavity units 110 having an ordered distribution and the characteristic wavelengths of their transmission spectra is also possible and beneficial. In addition, the requirements for the spectral characteristics (such as the resonant modes, the widths and transmittances of the characteristic spectral peaks, etc.) of the different microcavity units 110 are relatively lenient; of course, the greater the difference between them and the smaller the width of the characteristic spectral peak, the more beneficial it is to obtain a more accurate and high-resolution test spectrum after spectral reconstruction.

[0062] It should be emphasized that the relatively large tolerance of the microcavity array 100 in the micro spectrometer module according to the embodiments of the present invention for the shapes, arrangement manners and resonant spectral characteristics of the microcavity units 110 therein is based on the characteristics of the micro spectrometer described in the embodiments of the present invention and the manner of obtaining the spectrum (that is, obtaining the spectrum through the preset calibration information based on quasi-monochromatic light and spectral reconstruction calculation).

[0063] Of course, the above-mentioned tolerance is often also a disposal method for comprehensively considering the problems faced in the implementation process of the micro spectrometer module according to the embodiments of the present invention. In a preferred case, it is desired that the microcavity units 110 in the microcavity unit 110 have regular shapes, excellent resonant spectral characteristics, and are arranged in a regular manner, which will be beneficial to improving the data processing efficiency in spectral reconstruction during spectral testing of the micro spectrometer module, as well as the accuracy and spectral resolution of the obtained spectrum and other related performances.

[0064] Figure 6 is a schematic plan view of the microcavity unit 111 in the microcavity array 100 in the micro spectrometer module according to the embodiments of the present invention. As shown in the figure, different microcavity units 111 (R j , j = 1, 2, …, J) have different thicknesses t d(j) , j = 1, 2, …, J) of the intracavity dielectric layer 114, and thus correspondingly have different transmission spectral characteristics.

[0065] Figure 7It is a schematic plan view of the detector array 200, its detector unit pixel 211, and the planned detector unit 210 in the micro-spectrometer module according to an embodiment of the present invention. The in-plane size of the inherent detector unit pixel 211 in the detector array 200 on the market (such as several micrometers to dozens of micrometers) is often much smaller than the suitable in-plane size of the microcavity unit 110 in the microcavity array 100 (such as dozens of micrometers to hundreds of micrometers). Therefore, multiple detector unit pixels 211 in the detector array 200 can be planned as one detector unit 210, so that the detector unit 210 and the corresponding and aligned microcavity unit 110 in the microcavity array 100 have as close shapes and in-plane sizes as possible. Thus, each microcavity unit 110 in the microcavity array 100 has a corresponding and aligned detector unit 210 in the detector array 200; in this process, some detector unit pixels 211 in the detector array 200 do not have corresponding microcavity units 110 and are not divided into any detector unit 210, then these detector unit pixels 211 can be regarded as invalid or processed otherwise.

[0066] Of course, if the in-plane size of the detector unit pixel 211 is large (such as about the same order of magnitude or larger than the in-plane size of the microcavity unit 110 to be designed), it is necessary to consider comprehensively and design and manufacture the microcavity array 100 and its microcavity unit 110 according to the shape, size, and arrangement layout of the detector unit pixels 211 in the detector array 200, or design and manufacture the detector array 200 and its detector unit pixels 211 according to the shape, size, and arrangement layout of the microcavity units 110 in the microcavity array 100 to make them match each other.

[0067] For the planning and processing of the detector unit pixels 211 and detector units 210 in the detector array 200 described above, it is carried out in the later data processing process after converting the optical signals received by each detector unit pixel 211 in the detector array 200 into electrical signals.

[0068] Figure 8 It shows a spectral test system of the micro-spectrometer module according to an embodiment of the present invention, including the described micro-spectrometer module and a signal processing system 410, a control system 420, and an input / output terminal 430 that match it.

[0069] The spectrometer module according to an embodiment of the present invention can be used integrated with the signal processing system 410, the control system 420, and the input / output terminal 430 in the same device; or the signal processing system 410, the control system 420, and the input / output terminal 430 are integrated in one or several other independent devices and are used in cooperation with the spectrometer module through wired or wireless connection methods.

[0070] InFigure 8 In the shown spectral test system, the signal light to be measured is incident on the microcavity array 100 after passing through the signal light acquisition and beam shaping optical path 300. The transmitted light of different microcavity units 110 is respectively irradiated on the corresponding detector units 210. The optical signals received by each detector unit 210 in the detector array 200 are converted into electrical signals through photoelectric conversion, and after pre-signal processing and analog-to-digital (A / D) conversion, they are transmitted to the signal processing system 410 of the test system by wired or wireless means, and then spectral reconstruction is performed in combination with the preset calibration information.

[0071] Figure 9 Shown is a preset calibration test system for a micro-spectrometer module according to an embodiment of the present invention, which uses the quasi-monochromatic lights output by the calibration light source 500 to obtain the preset calibration information of a specific micro-spectrometer module to be preset calibrated on the basis of the shown spectral test system. Figure 8 Shown is a preset calibration test system for a micro-spectrometer module according to an embodiment of the present invention, which uses the quasi-monochromatic lights output by the calibration light source 500 to obtain the preset calibration information of a specific micro-spectrometer module to be preset calibrated on the basis of the shown spectral test system.

[0072] The calibration light source 500 can be a wavelength-tunable quasi-monochromatic light source composed of multiple quasi-monochromatic light sources with different wavelengths (such as light-emitting diodes LED or laser diodes LD), or a light source that realizes the output of quasi-monochromatic lights with different wavelengths by tuning the parameters of the internal resonant cavity.

[0073] The calibration light source 500 can also be a light source system based on a broadband light source (such as xenon lamp, deuterium lamp, halogen lamp, etc.) and using a tunable monochromator or a tunable filter to obtain quasi-monochromatic lights with different wavelengths.

[0074] The following briefly describes the methods and processes for performing preset calibration tests on a specific micro-spectrometer module according to an embodiment of the present invention and for performing spectral tests on the signal light.

[0075] The preset calibration test on the specific micro-spectrometer module is carried out after its hardware system has been manufactured and packaged. Assume that within the working wavelength range of the specific micro-spectrometer module, the wavelength of the quasi-monochromatic light output by the calibration light source 500 is λ i (i = 1, 2,..., I; where I is the number of wavelengths of the quasi-monochromatic light within the working wavelength range), and the corresponding output power of this quasi-monochromatic light is P c (λ i ). Assume that the normalized spectral curve of the quasi-monochromatic light at the wavelength λ i is I ci (λ), then there can be P c (λ i ) = A(λ i )I ci (λ), where A(λ i ) is the normalization constant corresponding to each quasi-monochromatic light.

[0076] Refer toFigure 9 As shown, in the case where quasi-monochromatic light with different wavelengths λ i from the calibration light source 500 is respectively input, the electrical signals generated by each detector unit 210 in the detector array 200 of the specific micro spectrometer module are output to the signal processing system 410 after preprocessing and analog-to-digital (A / D) conversion. The intensity represented by the digital signal corresponding to the intensity of the calibration light signal received by each detector unit 210 is c 0j (λ i )(j = 1, 2, …, J; here J is the number of detector units 210 in the detector array 200). And let c j (λ i ) = c 0j (λ i ) / P0(λ i ) be the calibration signal intensity corresponding to each detector unit 210 relative to the output quasi-monochromatic light power of the calibration light source 500.

[0077] It should be noted here that the preset calibration information includes not only the information of the quasi-monochromatic light output by the calibration light source 500 and the information of the calibration signal intensity generated after the quasi-monochromatic light output by the calibration light source 500 is input into the specific micro spectrometer module, but also the integration time (or exposure time) set by the control system 420 in the preset calibration test system for the detector array 200. Generally speaking, the number of photons received by each detector unit 210 in the detector array 200 and the intensity of the electrical signal generated are often proportional to the integration time. Here, let the integration time of the detector array 200 set in the preset calibration test be t c .

[0078] The preset calibration information obtained after the above preset calibration test can be stored in the memory of the specific micro spectrometer module or the signal processing system 410 bound thereto, etc., for calling during spectral reconstruction calculation in spectral testing in applications; or stored in the data storage system of a remote server, etc., and indexed and called through the device number set for the specific micro spectrometer module.

[0079] Referring to Figure 8 as shown, in spectral testing, let the integration time of the detector array 200 in the specific micro spectrometer module set by the control system 420 be t r ; when the signal light to be measured from the target object is collected by this micro spectrometer module, the intensity represented by the digital signal corresponding to the intensity of the signal light received by each detector unit 210 obtained in the signal processing system 410 is r 0j(j = 1, 2, …, J). Considering the influence of the different integration times of the detector array 200 on the generated signal intensity, let r j = r 0j (t r / t c ). Then the actual spectrum s(λ) of the signal light from the object to be measured can be calculated for its discrete solution s(λ i ) based on the following formula.

[0080]

[0081] Or written as: R = CS, where: R = [r j T , C = [c j (λ i )], S = [s(λ i )] T . A noise term N = [n j T can also be introduced into the above formula, so that the above formula is written as: R = CS + N.

[0082] It is hereby explained that multiplying the matrices R, C, and S in the above formula by constants related to characterizing normalization, discretization, or physical quantity conversion does not change the meaning and applicability of the above formula.

[0083] As can be seen from the previous description, the calibration and test data represented by the matrices C and R here include the optical response and photoelectric conversion factors of each part and component inside the specific micro spectrometer module to be calibrated, the structural deviation during the manufacturing process and the alignment deviation between each part, as well as the comprehensive influence of some other uncontrollable and unclear factors on the spectral test.

[0084] In the process of solving the above formula, if I = J, theoretically, the discrete actual spectrum S = C -1 R can be calculated by solving the inverse matrix of C. However, in many cases, it is desired to calibrate based on a limited number of detector units J with quasi-monochromatic light with a smaller interval and narrower linewidth (i.e., a larger number of calibration wavelengths I) within the working band during pre-calibration to obtain a test spectrum with higher resolution; thus, there will be J < I. In this case, it is necessary to calculate the actual spectrum S by solving the pseudo-inverse matrix of C; however, in this case, affected by the noise and various uncontrollable factors in the system, the calculation result may be unstable to a certain extent. In the actual numerical solution process of the above matrix equation, the actual spectrum S with the minimum error is often calculated by minimizing ||CS - R|| 2 . In specific implementation, relevant problems can be improved by other better algorithms.

[0085] ​​Figure 10 (a) shows the normalized spectral curves I i of monochromatic lights with different wavelengths λ ci during the preset calibration of the micro-spectrometer module according to an embodiment of the present invention, and their corresponding line widths δλ i and wavelength intervals Δλ i between adjacent monochromatic lights. Figure 10 (b) shows the intensity distribution c i of the corresponding signals generated by monochromatic lights with different wavelengths λ j on each detector unit 210 of the detector array 200 i (λ

[0086] during the preset calibration.

[0087] Example 1:

[0088] As shown Figure 11 , taking the preparation of the microcavity array 100 with 31 microcavity units 110 having different thicknesses of the intracavity dielectric layer 114 as an example: First, deposit the first reflective layer metal thin film 112 of each microcavity unit 110 in the microcavity array 100; then, as shown in Figure 11 (a)-(e), deposit the material thin films of the intracavity dielectric layer 114 with different specific thicknesses (such as the thicknesses are a, b, c, d, e respectively) in the regions of different specific microcavity units 110 5 times by a known thin film deposition process (such as electron beam evaporation, thermal evaporation, magnetron sputtering, or chemical vapor deposition method, etc.), and finally form the microcavity units 110 with 31 intracavity dielectric layers 114 having different thicknesses as shown in Figure 11 (f); finally, deposit the second reflective layer metal thin film 113 of each microcavity unit 110 in the microcavity array 100.

[0089] Using this method, based on depositing the material thin films of the intracavity dielectric layer 114 with different specific thicknesses in the regions corresponding to different specific microcavity units 110 N times (such as 8 times), microcavity units 110 with (2 N -1) (such as 255) intracavity dielectric layers 114 having different thicknesses can be formed. In the design of the microcavity array 100 in the micro-spectrometer module, generally, first design the number of microcavity units 110, preferably the number of microcavity units 110 close to the number of (2 N -1), such as 2 Npieces, and then design the regions of specific microcavity units 110 corresponding to N times of thin film deposition of the intracavity dielectric layer 114 respectively. As Figure 11 As shown in (f), finally, there is a unit region (shaded region) without the intracavity dielectric layer 114, which can be regarded as invalid or otherwise processed. The deposition of the dielectric thin film in the specific region can be realized based on coating equipment, lithography equipment, etching equipment, etc. and their related processes.

[0090] Embodiment 2:

[0091] As Figure 12 shown, taking the preparation of a microcavity array 100 with 30 microcavity units 110 having intracavity dielectric layers 114 with different thicknesses as an example: First, deposit the first reflective layer metal thin film 112 of each microcavity unit 110 in the microcavity array 100; then, as Figure 12 shown in (a), deposit the material thin films of the intracavity dielectric layer 114 with different specific thicknesses in the regions of different specific microcavity units 110 in 6 times, forming a region of the intracavity dielectric layer 114 material thin film with 6 different thicknesses (a, a + Δa,..., a + 5Δa) as shown in Figure 12 (a) (here the step size of the thickness change may not be the same Δa); again, as Figure 12 shown in (b), in another direction, deposit the material thin films of the intracavity dielectric layer 114 with different specific thicknesses (Δb, 2Δb, 3Δb, 4Δb) in the regions of different specific microcavity units 110 in 4 times (here the step size of the thickness change may not be the same Δb); through the above 9 times of coating, finally form 30 microcavity units 110 with intracavity dielectric layers 114 having different thicknesses as shown in Figure 12 (b); finally, deposit the second reflective layer metal thin film 113 of each microcavity unit 110 in the microcavity array 100.

[0092] Using this method, based on (M + N) times (such as 16 + 15 = 31 times) of depositing the material thin films of the intracavity dielectric layer 114 with different specific thicknesses in the regions corresponding to different specific microcavity units 110, M×(N + 1) (such as 256) microcavity units 110 with intracavity dielectric layers 114 having different thicknesses can be formed. The change in the thickness between the adjacent dielectric thin film layers described above may not be a monotonous stepped change, but a specific and arbitrary other change manner.

[0093] Comparing the above Embodiment 1 with Embodiment 2, Embodiment 1 is more effective in terms of the number of process steps or the number of intracavity dielectric layers with different thicknesses obtained, but Embodiment 2 may be more orderly in the thickness distribution of the different intracavity dielectric layers prepared.

[0094] Embodiment 3:

[0095] The description is as follows: First, deposit the first reflective layer metal thin film 112 of each microcavity unit 110 in the microcavity array 100; then, disperse many randomly distributed discrete dielectric flakes with randomly varying thicknesses within the micro-nano scale on the first reflective layer metal thin film 112, and use these dielectric flakes as the intracavity dielectric layer 114 in each microcavity unit 110; finally, deposit the second reflective layer metal thin film 113 of each microcavity unit 110 in the microcavity array 100.

[0096] The microcavity units 110 prepared based on this method are randomly distributed irregularly in the microcavity array 100. The dielectric flakes can be powder materials prepared by chemical synthesis methods or mechanical grinding methods. The dielectric flakes can have irregular shapes and randomly distributed thicknesses. Their planar sizes can be approximately in the range of 10 - 1000 μm, and their thicknesses can be randomly distributed in the range of approximately 10 - 50000 nm according to the designed working wavelength band of the spectrometer module.

[0097] The above are only embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural or equivalent process transformation made using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall similarly be included within the patent protection scope of the present invention.

Claims

1. A method for implementing a micro spectrometer module based on a metal microcavity array, characterized in that: The micro-spectrometer module includes a microcavity array and a detector array. A plurality of microcavity units are arranged in the microcavity array. Each microcavity unit has a Fabry-Perot structure with a metal thin film with a thickness of 5-100 nm as the reflective layer. Different microcavity units have different thicknesses of the intracavity dielectric layer; In the preparation of the microcavity array, the preparation of the intracavity dielectric layers with different thicknesses is achieved by selectively depositing thin film stacks in different regions of the microcavity array multiple times through a thin film deposition process. The number of thin film depositions of the intracavity dielectric layer material with different thicknesses is less than the number of microcavity units in the microcavity array with intracavity dielectric layers of different thicknesses; through N thin film deposition processes of the intracavity dielectric layer material, at most (2 N - 1) microcavity units with intracavity dielectric layers of different thicknesses can be formed; The described detector array is composed of its inherent multiple detector unit pixels. The detector array is planned to have multiple detector units, and each detector unit contains one or more detector unit pixels; Each microcavity unit in the microcavity array corresponds to each detector unit in the detector array respectively; Before use, the micro-spectrometer module is pre-calibrated using a pre-calibration test system with a calibration light source being a wavelength-tunable quasi-monochromatic light. During use, the spectrum is obtained based on the pre-calibration information and spectral reconstruction calculation.

2. The implementation method of a miniature spectrometer module based on a metal microcavity array according to claim 1, characterized in that: The described micro-spectrometer module combines with a signal processing system, a control system and an input / output terminal that match it to perform spectrum testing and acquisition; The micro-spectrometer module can be integrated with peripheral devices into one body, or be set independently and used in combination through signal transmission with peripheral devices.

3. The implementation method of a miniature spectrometer module based on a metal microcavity array as claimed in claim 1, wherein: Each microcavity unit in the microcavity array is connected to or isolated from each other; Each microcavity unit in the microcavity array is arranged in a regular or irregular manner; The shape of each microcavity unit in the microcavity array is a regular or irregular shape.

4. The implementation method of a micro spectrometer module based on a metal microcavity array according to claim 1, characterized in that: The calibration light source therein is a wavelength-tunable quasi-monochromatic light source composed of multiple quasi-monochromatic light sources with different wavelengths, or a light source that realizes the output of quasi-monochromatic light with different wavelengths by tuning the parameters of the internal resonant cavity.

5. The implementation method of a micro spectrometer module based on a metal microcavity array according to claim 1, characterized in that: The calibration light source therein is to obtain quasi-monochromatic light with different wavelengths based on a broadband light source using an adjustable monochromator or an adjustable filter.

6. The implementation method of a miniature spectrometer module based on a metal microcavity array as described in claim 1, characterized in that: The method for obtaining the spectrum based on pre-calibration and spectral reconstruction calculation is as follows: Suppose the preset calibration information of the spectral analysis module used includes: the wavelength of the quasi-monochromatic light output by the calibration light source is λ i (i = 1, 2, …, I), and the corresponding output power is P0(λ i ), the integration time of the set detector array is t c , and the intensity represented by the digital signal corresponding to the optical signal intensity received by each detector unit in the detector array is c 0j (λ i )(j = 1, 2, …, J); Suppose that in the test of the optical signal to be measured, the intensity characterized by the digital signal corresponding to the optical signal intensity received by each detector unit in the detector array is r 0j (j = 1, 2, …, J), and the integration time of the set detector array is t r ; Let c j (λ i ) = c 0j (λ i ) / P0(λ i ), r j = r 0j (t r / t c ). Then the actual spectrum s(λ) of the signal light to be measured can be reconstructed by calculating its discrete solution s(λ i ) based on the following expression: Written as: R = CS, where R = [r j T , C = [c j (λ i )], S = [s(λ i )] T ; Further introduce a noise term N = [n j T , so that the above formula is written as: R = CS + N; Further, the matrices R, C, and S in the above formula are multiplied by constants related to characterizing normalization, discretization, or physical quantity conversion, etc.​​ 7. The implementation method of a micro spectrometer module based on a metal microcavity array according to claim 1, characterized in that: The preparation method of the intracavity dielectric layer in the microcavity array is as follows: deposit thin films of intracavity dielectric layer materials with different thicknesses in the regions of multiple different microcavity units in the microcavity array for N times, and finally form microcavity units with (2 N - 1) intracavity dielectric layers with different thicknesses.

8. The implementation method of a miniature spectrometer module based on a metal microcavity array according to claim 1, characterized in that: The preparation method of the intracavity dielectric layer in the microcavity array is: First, deposit thin films of intracavity dielectric layer materials with different thicknesses in the regions of different multiple microcavity units in the microcavity array in M times, forming M regions of thin films of intracavity dielectric layer materials with different thicknesses; Then, deposit thin films of intracavity dielectric layer materials with different thicknesses in the regions of another different multiple microcavity units in the microcavity array in N times in another direction; Through (M + N) times of coating, finally form microcavity units with M×(N + 1) different thicknesses of intracavity dielectric layers.

9. The implementation method of a micro spectrometer module based on a metal microcavity array according to claim 1, characterized in that: The preparation method of the intracavity dielectric layer in the microcavity array is: Scatter a large number of randomly distributed discrete dielectric flakes with random thicknesses (in the range of 10 nm to 50 μm) and in-plane sizes in the range of 10 to 1000 μm on the first reflective layer metal thin film in the microcavity array, and use the dielectric flakes with different thicknesses as the intracavity dielectric layers in each microcavity unit in the microcavity array.

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