A tuning type spectral detection system and spectral detection method

Abstract

The application discloses a kind of tuning type spectral detection system and spectral detection method.The tuning type spectral detection system includes total reflection light coupling element, light tuning unit and light detection unit;The total reflection light coupling element can carry out total reflection to incident light and produce evanescent wave, and the incident light includes selected wavelength light;The light tuning unit includes: metal layer, which can be excited by the evanescent wave generated by the selected wavelength light to generate surface plasmon wave, and can absorb the surface plasmon wave, refractive index adjustable module is used to adjust the refractive index of the environment where the metal layer surface is located to at least change the coupling condition of the surface plasmon wave;The light detection unit is at least used for detecting the light intensity of reflected light output by the light tuning unit and converting into electrical signal output.The tuning type spectral detection system provided by the application can realize wide range wavelength detection, and has the advantages of high detection precision and integration.

Description

Technical Field

[0001] This invention belongs to the field of detection equipment technology, specifically relating to a tuned spectral detection system and spectral detection method. Background Technology

[0002] Spectroscopic detection is a crucial technique in material analysis, with significant applications in remote sensing mapping, pharmaceutical development, food health, environmental monitoring, and agriculture and forestry. Spatial spectroscopic detection methods, whether using gratings or filter arrays, require substantial equipment space and detector arrays, resulting in complex, bulky, and expensive equipment. Time-domain spectroscopic detection methods are often limited by the Fourier transform mechanism, requiring large interference optical paths. Tuned spectroscopic detection methods, especially those that resolve unknown spectra by tuning the spectral response of a single test and combining it with compressed sensing algorithms, require only a single detector and eliminate the need for complex interference optical paths, offering advantages in simplicity and low cost. However, their spectral detection range is limited by the wavelength tuning range, and the separate tuning and detection modules increase the difficulty of optical coupling and integration. Summary of the Invention

[0003] The main objective of this invention is to provide a tuned spectral detection system and spectral detection method to overcome the shortcomings of the prior art.

[0004] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0005] This invention provides a tuned spectral detection system, which includes a total internal reflection optical coupling element, an optical tuning unit, and an optical detection unit;

[0006] The total internal reflection optical coupling element is capable of total internal reflection of incident light and generating an evanescent wave, wherein the incident light includes light of a selected wavelength;

[0007] The optical tuning unit includes:

[0008] A metal layer capable of generating surface plasmon waves by being excited by evanescent waves produced by light of the selected wavelength, and capable of absorbing the surface plasmon waves.

[0009] A refractive index adjustable module is used to adjust the refractive index of the environment surrounding the surface of the metal layer, so as to at least change the coupling conditions of the surface plasma wave.

[0010] The light detection unit is at least used to detect the intensity of the reflected light output by the light tuning unit and convert it into an electrical signal output.

[0011] This invention also provides a spectral detection method, comprising:

[0012] The above-mentioned tuned spectral detection system is provided;

[0013] The incident light to be measured is collimated by the optical collimating unit and then incident on the total internal reflection optical coupling element for total internal reflection, generating reflected light.

[0014] The refractive index of the optical tuning unit is changed to tune the reflected light, and the intensity of the reflected light is detected by the optical detection unit.

[0015] The relationship between the light intensity detected by the optical detection unit and the light intensity detected by the optical detection unit under the same refractive index environment with different single-wavelength incident light is analyzed to obtain the spectral information of the incident light being measured.

[0016] Compared with existing technologies, the advantages of the tuned spectral detection system and spectral detection method provided by this invention include:

[0017] 1) The incident light and surface plasma wave are coupled by total internal reflection. The extremely high sensitivity of this coupling dispersion relationship to the refractive index of the environment is utilized. Combined with the refractive index tunable material technology, a wide range of wavelength tuning is achieved, which far exceeds the wavelength tuning technology of various microstructures. Thus, a tuned spectral detection system with wide spectrum operation is realized.

[0018] 2) The non-resonant broadband reflected light signal received by the photodetector unit is adjusted by the tunable resonant absorption surface plasma wave, thereby improving the signal-to-noise ratio.

[0019] 3) The optical tuning unit and the optical detection unit are structurally separate, but they are both integrated on the transparent dielectric layer and share a metal layer as electrodes. They do not require optical coupling elements such as lenses, and can be optimized independently while having the advantage of high integration.

[0020] 4) By coating the first and second surfaces of the transparent dielectric layer with metal films, light can be recycled based on multiple reflections, which is beneficial to improving the efficiency of the optical tuning unit and the response of the optical detection unit.

[0021] 5) By repeatedly tuning the response wavelength of the optical detection unit and detecting the reflected light, the relationship between the wavelength and the photoelectric response output can be analyzed, and a large operating wavelength range and high-resolution spectral detection capability can be obtained based on a single optical detection system. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of a tuned spectral detection system provided in Embodiment 1 of the present invention;

[0024] Figure 2 The result is the calculated absorption spectrum of the tuned spectral detection system in Embodiment 1 of the present invention;

[0025] Figure 3 This is a schematic diagram of the structure of a tuned spectral detection system provided in Embodiment 2 of the present invention;

[0026] Figure 4 The result is the calculated absorption spectrum of the tuned spectral detection system in Embodiment 2 of the present invention;

[0027] Figure 5a The result is the calculation result of the spectral test performed by the tuned spectral detection system in Embodiment 2 of the present invention;

[0028] Figure 5b This is another calculation result of the spectral testing performed by the tuned spectral detection system in Embodiment 2 of the present invention;

[0029] Figure 5c This is another calculation result of the spectral testing performed by the tuned spectral detection system in Embodiment 2 of the present invention;

[0030] Figure 6 This is the calculated result of the reflectance spectrum of the tuned spectral detection system in Embodiment 3 of the present invention. Detailed Implementation

[0031] In view of the deficiencies of the prior art, the inventors of this case, through long-term research and extensive practice, have been able to propose the technical solution of this invention. The following will further explain the technical solution, its implementation process and principle.

[0032] One aspect of the present invention provides a tuned spectral detection system, which includes a total internal reflection optical coupling element, an optical tuning unit, and an optical detection unit;

[0033] The total internal reflection optical coupling element is capable of total internal reflection of incident light and generating an evanescent wave, wherein the incident light includes light of a selected wavelength;

[0034] The optical tuning unit includes:

[0035] A metal layer capable of generating surface plasmon waves by being excited by evanescent waves produced by light of the selected wavelength, and capable of absorbing the surface plasmon waves.

[0036] A refractive index adjustable module is used to adjust the refractive index of the environment surrounding the surface of the metal layer, so as to at least change the coupling conditions of the surface plasma wave.

[0037] The light detection unit is at least used to detect the intensity of the reflected light output by the light tuning unit and convert it into an electrical signal output through a photoelectric conversion mechanism.

[0038] Furthermore, the optical tuning unit also includes a transparent dielectric layer and a reflective layer. The transparent dielectric layer has a first surface and a second surface opposite to each other. The reflective layer is covered on the first surface and located between the first surface and the total reflection surface of the total reflection optical coupling element. The metal layer is covered on the second surface and located between the second surface and the refractive index adjustable module.

[0039] The material of the transparent dielectric layer can be sapphire, quartz glass, gallium nitride, aluminum nitride, etc., but is not limited to these.

[0040] Furthermore, the refractive index adjustable module includes a refractive index adjustable layer disposed on the surface of the metal layer and located between the metal layer and the electrode, and the refractive index of the refractive index adjustable layer changes with the voltage applied between the metal layer and the electrode.

[0041] The material of the refractive index adjustable layer can be liquid crystal, vanadium oxide, phase change material, etc., but is not limited to these.

[0042] Furthermore, the total reflection surface of the total reflection optical coupling element is bonded to the reflective layer through a refractive index matching layer.

[0043] Furthermore, the reflective layer is provided with a first window through which incident light can pass, the first window allowing the incident light to undergo total internal reflection at the interface between the metal layer and the second surface and form a first reflected beam.

[0044] Furthermore, the metal layer is provided with a second window through which the second reflected light beam can pass. The second reflected light beam is formed by the reflection of the first reflected light beam through the reflective layer. The second window allows the second reflected light to enter the photosensitive surface of the light detection unit.

[0045] In some embodiments, a dielectric layer for adjusting the coupling dispersion relationship of total internal reflection is further provided between the metal layer and the refractive index adjustable layer.

[0046] Furthermore, the difference in refractive index between any two of the refractive index matching layer, the transparent dielectric layer, and the total internal reflection optical coupling element is within 10%.

[0047] Furthermore, the reflective layer comprises a metal film with a thickness of 100 nm or more.

[0048] Furthermore, the metal layer includes a first region and a second region, wherein the first region cooperates with the optical tuning unit and has a thickness of 10-80 nm, while the second region has a thickness of more than 100 nm.

[0049] The metal layer, reflective layer, and electrodes may be made of one or more of the following materials: gold, silver, aluminum, copper, titanium, cadmium, platinum, etc., and are not limited thereto.

[0050] Furthermore, the tuned spectral detection system also includes an optical collimation unit, which is used to collimate the incident light before it is incident on the total internal reflection optical coupling element.

[0051] Furthermore, the total internal reflection optical coupling element includes a right-angle prism or a semi-circular lens.

[0052] Furthermore, the optical detection unit includes photodetectors or photothermal detectors, etc.

[0053] The tuned spectral detection system provided in the above embodiments of the present invention exhibits strong absorption of incident light at a specific wavelength (i.e., the selected wavelength) that meets the wave vector matching condition by surface plasmon waves of the metal layer. Furthermore, this specific wavelength can be highly sensitively tuned by changing the refractive index of the tunable layer. Therefore, even a small change in refractive index can yield significant tuning of the reflection spectrum, resulting in a sufficient number of differentiated spectral responses over a wide wavelength range. This is highly beneficial for compressed sensing algorithms to resolve high-precision raw spectra over a broad spectral range. In addition, while the optical tuning unit and optical detection unit are structurally separate, they are both integrated on the transparent dielectric layer and share a single electrode, offering the advantages of both independent optimization and high integration.

[0054] Another aspect of the present invention provides a spectral detection method, comprising:

[0055] The above-mentioned tuned spectral detection system is provided;

[0056] The incident light to be measured is collimated by the optical collimating unit and then incident on the total internal reflection optical coupling element for total internal reflection, generating reflected light.

[0057] The refractive index of the optical tuning unit is changed to tune the reflected light, and the intensity of the reflected light is detected by the optical detection unit.

[0058] The relationship between the light intensity detected by the optical detection unit and the light intensity detected by the optical detection unit under the same refractive index environment with different single-wavelength incident light is analyzed to obtain the spectral information of the incident light being measured.

[0059] Furthermore, the spectral detection method specifically includes:

[0060] The metal layer is electrically connected to the electrode, and a bias voltage is applied to the refractive index adjustable layer to adjust the refractive index of the refractive index adjustable layer, thereby changing the coupling condition of the surface plasma wave absorbed by the metal layer, and thus tuning the intensity of the reflected light.

[0061] The detection electrode of the photosensitive surface of the photodetector unit is electrically connected to the metal layer, thereby converting the light intensity of the reflected light received by the photosensitive surface of the photodetector unit into an electrical signal.

[0062] Furthermore, the spectral detection method specifically includes:

[0063] (1) The wavelength range that the reconfigurable optical detection system can detect is divided into N bands with a bandwidth of Δλ, where N is an integer not less than 3, and the center wavelength of each band is λ1, λ2, ..., λ3. N ;

[0064] (2) Divide the refractive index of the tunable layer into M values, where M is an integer not less than 3. The refractive indices of the tunable layer are denoted as n1, n2, ..., n M ;

[0065] (3) When the refractive index of the adjustable layer is taken as the i-th value, the center wavelength is λ1, λ2, ..., λ N After a single-wavelength incident light is incident on the total internal reflection optical coupling element, the light intensity measured by the light detection unit is denoted as I. i1 I i2 , ..., I iN ;

[0066] (4) The refractive indices of the unknown incident light in the tunable refractive index layer are n1, n2, ..., n M At that time, the electrical signals measured by the optical detection unit are denoted as I1, I2, ..., I... M The spectral information of the incident light being measured is obtained by solving the following matrix equations;

[0067]

[0068] Formula (1)

[0069] Among them, C ij (i = 1, 2, ..., M)(j = 1, 2, ..., N) represents a center wavelength of λ. j When the refractive index of the tunable refractive index layer takes the i-th value, the light intensity I measured by the light detection unit is... ij .

[0070] The spectral detection method provided in the above embodiments of the present invention involves collimating the incident light to be measured through a beam collimation unit and then incident it onto a total internal reflection optical coupling element and a transparent dielectric layer. By applying a voltage between the electrode on the refractive index-tunable layer and the metal layer on the second surface of the transparent dielectric layer, the refractive index of the refractive index-tunable layer is adjusted, thereby changing the coupling conditions between the total internal reflection process on the second surface of the transparent dielectric layer and the surface plasma wave on the metal layer, thus adjusting the spectrum of the reflected light. By changing the bias voltage multiple times and detecting the intensity of the corresponding reflected light through a light detection unit, the relationship between the wavelength and the intensity of the reflected light is analyzed, thereby achieving spectral detection of the incident light.

[0071] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments of the present invention are implemented on the premise of the technical solution of the invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0072] Example 1

[0073] Please see Figure 1 The tunable spectral detection system in this embodiment includes a beam collimation unit 2, a right-angle prism 3, a refractive index matching layer 4, a light detection unit 5, a transparent dielectric layer 6, a reflective layer 71, a metal layer 72, a refractive index adjustable layer 8, and an electrode 9. The transparent dielectric layer 6, the reflective layer 71, the metal layer 72, the refractive index adjustable layer 8, and the electrode 9 together constitute the light tuning unit of the tunable spectral detection system.

[0074] The transparent dielectric layer 6 has a first surface and a second surface opposite to each other, the reflective layer 71 is covered on the first surface, and the metal layer 72 is covered on the second surface.

[0075] Specifically, the reflective layer 71 is provided with a first window 711 through which incident light can pass. The first window 711 allows the incident light to undergo total internal reflection at the interface between the metal layer 72 and the second surface to form a first reflected beam. The first reflected beam undergoes total internal reflection again through the reflective layer 71 to form a second reflected beam. The above reflection process can be performed multiple times, and the final reflected beam enters the photosensitive surface of the light detection unit 5 through the second window 721 on the metal layer 72.

[0076] Specifically, the metal layer 72 includes a first region and a second region. The first region is used in conjunction with the optical tuning unit, while the optical detection unit 5 is correspondingly disposed on the second region. The first region of the metal layer 72 is used to excite surface plasma waves. Its thickness cannot be too thick, otherwise the incident light will not be able to penetrate the metal layer to excite surface plasma resonance. The second region of the metal layer 72 is used to reflect light and make the reflected light finally received by the optical detection unit 5. Its thickness cannot be too thin, otherwise it will cause light leakage.

[0077] Specifically, the beam collimation unit 2 is a lens group, the total internal reflection optical coupling element is an SF11 direct prism, the optical detection unit 5 is an indium gallium arsenide detector, the transparent dielectric layer 6 is made of sapphire, the reflective layer 71 is a 150-nanometer-thick gold film, the first region of the metal layer 72 is a 40-nanometer-thick gold film, the second region is a 150-nanometer-thick gold film, the refractive index adjustable layer 8 is made of liquid crystal with a thickness of 4 micrometers, and the electrode 9 is a 150-nanometer-thick gold film.

[0078] In this embodiment of the tuned spectral detection system, incident light 1 passes through beam collimation unit 2 and then onto the non-total reflection surface 31 of right-angle prism 3. It then passes through the total reflection surface 32 of right-angle prism 3 and the first window on reflective layer 71 before entering transparent dielectric layer 6. Total reflection occurs at the interface between metal layer 72 and transparent dielectric layer 6, thereby exciting surface plasmon waves of a specific wavelength on the surface of metal layer 72. By forming an electrical connection between metal layer 72 and electrode 9 and applying a bias voltage to refractive index-tunable layer 8 to change the refractive index of refractive index-tunable layer 8, the coupling conditions of surface plasmon waves on metal layer 72 are changed, thus achieving tuning of the reflected light spectrum. After multiple reflections, reflected light 10 passes through the second window on metal layer 72 and enters the photosensitive surface of light detection unit 5 for detection.

[0079] For details, please refer to Figure 2 Incident light 1, after being collimated by beam collimation unit 2, is incident at an angle of 63 degrees onto the interface between metal layer 72 and transparent dielectric layer 6. When the refractive index of the tunable layer 8 is 1.52, the corresponding resonant wavelength is 1200 nm, while when the refractive index of the tunable layer 8 is 1.53, the corresponding resonant wavelength is 1440 nm. A change in refractive index of 0.01 results in a shift of 240 nm in the resonant position.

[0080] Specifically, surface plasma waves exist at the interface between metal and dielectric, and their wave vector can be expressed as:

[0081] .

[0082] Where c is the speed of light in free space, and ω is the frequency of the incident light. The dielectric constant of the metal is ρ is the dielectric constant of the medium. When the wave vector of incident light 1 and the wave vector of the surface plasmon wave satisfy the matching condition, a surface plasmon wave can be excited. The energy of this specific wavelength of incident light is transferred to the surface plasmon wave and absorbed by the metal layer 72, corresponding to a minimum reflectivity in the reflection spectrum.

[0083] As can be seen from the above equation, the wave vector of the surface plasmon wave is related to the dielectric constant of the medium. By applying a bias voltage between the metal layer 72 and the electrode 9 to adjust the refractive index of the tunable layer 8, the wavelength of the surface plasmon wave is changed, thereby affecting the light absorption of the metal layer 72. The unabsorbed light is reflected to the interface between the transparent dielectric layer 6 and the reflective layer 71 and is reflected again. This reflected light can couple with the surface plasmon wave again on the surface of the metal layer 72 and be modulated by the tunable layer 8, enhancing the modulation depth. After multiple reflections, it enters the photodetector unit 5 through the second window on the metal layer 72, enhancing the photodetector responsivity. The response of the photodetector unit 5 is determined by the reflected light, i.e., it is also affected by the light absorption of the surface plasmon wave of the metal layer 72. By changing the bias voltage multiple times and recording the output of the photodetector unit, the relationship between the wavelength and the output electrical signal is analyzed, and spectral detection of the incident light is achieved.

[0084] Example 2

[0085] Please see Figure 3 The tuned spectral detection system in this embodiment is basically similar in structure to the tuned spectral detection system in embodiment 1. The difference is that a dielectric layer 11 is introduced between the metal layer 72 and the refractive index adjustable layer 8. The dielectric layer 11 can further adjust the resonant waveform and improve the tolerance range of the incident angle that causes total internal reflection of the incident light during actual testing.

[0086] Specifically, the dielectric layer 11 is a 50-nanometer-thick silicon nitride layer.

[0087] For details, please refer to Figure 4 Incident light 1 is incident at 69 degrees onto the interface between transparent dielectric layer 6 and metal layer 7-2. When the refractive index of the refractive index adjustable layer 8 gradually changes from 1.52 to 1.57, the resonant wavelength in the corresponding reflected light spectrum changes from 1.2 micrometers to 1.7 micrometers.

[0088] When using the tuned spectral detection system in this embodiment to perform spectral testing on the incident light, the specific steps include:

[0089] First, the response of different single-wavelength incident light is tested and calibrated using this tuned spectral detection system. Specifically, the voltage between the metal layer 72 and the electrode 9 is set to 2V, corresponding to a refractive index of 1.52 for the tunable refractive index layer 8. Different single-wavelength incident light is collimated and incident on the non-total reflection surface 31 of the right-angle prism 3, and then emitted from the total reflection surface 32 of the right-angle prism 3, exciting surface plasmon waves at the interface between the transparent dielectric layer 6 and the metal layer 72. At the same time, a series of photocurrent signals detected by the photodetector unit 5 are recorded. The voltage between the metal layer 72 and the electrode 9 is changed sequentially with a step size of 100mV, so that the refractive index of the tunable refractive index layer 8 changes from 1.52 to 1.57. At the same time, a series of photocurrent signals detected by the photodetector unit 5 are recorded, thereby obtaining the photocurrent matrix corresponding to the response of different single-wavelength incident light when the refractive index tunable layer 8 changes from 1.52 to 1.57, which is the transmission matrix C.

[0090] Then, the unknown incident light to be measured is detected. The voltage between the metal layer 72 and the electrode 9 is gradually adjusted according to the same voltage adjustment procedure in the calibration test. At the same time, a series of photocurrent signals detected in the photodetector unit 5 are recorded. Combined with the obtained transmission matrix C, the spectral information of the incident light to be measured can be solved by formula (1).

[0091] Please see Figures 5a to 5c The diagram shows a comparison of the spectral results of three different incident lights tested by a commercial spectrometer and the tuned spectral detection system in this embodiment. It can be seen that the tuned spectral detection system in this embodiment obtained spectral detection results that are highly consistent with those of the commercial spectrometer. At the same time, the tuned spectral detection system in this embodiment also has the advantage of high integration compared with existing commercial spectrometers.

[0092] Example 3

[0093] The tuned spectral detection system in this embodiment is also referred to. Figure 3 Its structure is the same as the tuned spectral detection system in Example 2, with one difference being that the thickness of the refractive index tunable layer 8 is 15 micrometers. Another difference is that the incident light 1, after being collimated by the beam collimating unit 2, is incident at an incident angle of 36 degrees onto the non-total reflection surface 31 of the right-angle prism 3. Next, please refer to... Figure 6The above represents the calculated reflection spectrum of the tuned spectral detection system in this embodiment. Multiple different resonances can be observed in the reflection spectrum. The resonance at the 1465 nm wavelength position is the surface plasmon resonance excited by the incident light in the metal layer 72, while the three narrower resonances at the 1250, 1404, and 1668 nm wavelength positions are the guided-mode resonance modes excited by the refractive index tunable layer 8. The guided-mode resonance mode is more sensitive to refractive index changes in the middle part of the refractive index tunable layer 8, while the surface plasmon resonance mode is more sensitive to refractive index changes in the part of the refractive index tunable layer 8 closer to the metal layer 72. When the external bias voltage changes, the refractive index of the refractive index tunable layer 8 changes, and the resonance positions of both resonance modes change. Compared to a single resonance mode, dual resonance modes can improve efficiency and spectral reconstruction resolution when performing spectral information scanning sampling with varying bias voltages.

[0094] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0095] It should be understood that the technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made to the technical solutions of the present invention without departing from the spirit and scope of the claims are within the scope of protection of the present invention.

Claims

1. A tuned spectral detection system, characterized in that, It includes a total internal reflection optical coupling element, an optical tuning unit, and an optical detection unit; The total internal reflection optical coupling element is capable of total internal reflection of incident light and generating an evanescent wave, wherein the incident light includes light of a selected wavelength; The optical tuning unit includes: A metal layer capable of generating surface plasmon waves by being excited by evanescent waves produced by light of the selected wavelength, and capable of absorbing the surface plasmon waves. A refractive index adjustable module is used to adjust the refractive index of the environment surrounding the surface of the metal layer to at least change the coupling conditions of the surface plasma wave; the refractive index adjustable module includes a refractive index adjustable layer disposed on the surface of the metal layer and located between the metal layer and the electrode, and the refractive index of the refractive index adjustable layer changes with the voltage applied between the metal layer and the electrode; A transparent dielectric layer and a reflective layer, wherein the transparent dielectric layer has a first surface and a second surface opposite to each other, the reflective layer is disposed on the first surface and located between the first surface and the total reflection surface of the total reflection optical coupling element, and the metal layer is disposed on the second surface and located between the second surface and the refractive index adjustable module; The reflective layer is provided with a first window through which incident light can pass. The first window allows the incident light to undergo total internal reflection at the interface between the metal layer and the second surface and form a first reflected beam. The metal layer is provided with a second window through which a second reflected beam can pass. The second reflected beam is formed by multiple reflections of the first reflected beam. The second window allows the second reflected light to enter the photosensitive surface of the light detection unit. The total reflection surface of the total reflection optical coupling element is bonded to the reflective layer through a refractive index matching layer; The light detection unit is at least used to detect the intensity of the reflected light output by the light tuning unit and convert it into an electrical signal output.

2. The tuned spectral detection system according to claim 1, characterized in that, A dielectric layer is also provided between the metal layer and the refractive index adjustable layer.

3. The tuned spectral detection system according to claim 1, characterized in that, The difference in refractive index between any two of the refractive index matching layer, the transparent dielectric layer, and the total internal reflection optical coupling element is within 10%.

4. The tuned spectral detection system according to claim 1, characterized in that, The reflective layer comprises a metal film with a thickness of 100 nm or more.

5. The tuned spectral detection system according to claim 1, characterized in that, The metal layer includes a first region and a second region, wherein the first region cooperates with the optical tuning unit and has a thickness of 10-80 nm, while the second region has a thickness of more than 100 nm.

6. The tuned spectral detection system according to claim 1, characterized in that, It also includes an optical collimation unit, which is used to collimate the incident light before it is incident on the total internal reflection optical coupling element.

7. A spectral detection method, characterized in that, include: Provide a tuned spectral detection system according to any one of claims 1-6; The incident light to be measured is collimated by the optical collimation unit and then incident on the total internal reflection optical coupling element for total internal reflection, generating reflected light. The refractive index of the optical tuning unit is changed to tune the reflected light, and the intensity of the reflected light is detected by the optical detection unit. The relationship between the light intensity detected by the optical detection unit and the light intensity detected by the optical detection unit under the same refractive index environment with different single-wavelength incident light is analyzed to obtain the spectral information of the incident light being measured.

8. The spectral detection method according to claim 7, characterized in that, Specifically, it includes: The metal layer is electrically connected to the electrode, and a bias voltage is applied to the refractive index adjustable layer to adjust the refractive index of the refractive index adjustable layer, thereby changing the coupling condition of the surface plasma wave absorbed by the metal layer, and thus tuning the intensity of the reflected light. The detection electrode of the photosensitive surface of the photodetector unit is electrically connected to the metal layer, thereby converting the light intensity of the reflected light received by the photosensitive surface of the photodetector unit into an electrical signal.

9. The spectral detection method according to any one of claims 7 or 8, characterized in that, Specifically, it includes: (1) The wavelength range that the tuned spectral detection system can detect is divided into N bands with a bandwidth of Δλ, where N is an integer not less than 3, and the center wavelength of each band is λ1, λ2, ..., λ3. N ; (2) Divide the refractive index of the tunable layer into M values, where M is an integer not less than 3. The refractive indices of the tunable layer are denoted as n1, n2, ..., n M ; (3) When the refractive index of the tunable layer is taken as the i-th value, the center wavelength is λ1, λ2, ..., λ N After a single-wavelength incident light is incident on the total internal reflection optical coupling element, the light intensity measured by the light detection unit is denoted as I. i1 I i2 , ..., I iN ; (4) The refractive indices of the unknown incident light in the tunable refractive index layer are n1, n2, ..., n M At that time, the electrical signals measured by the optical detection unit are denoted as I1, I2, ..., I... M The spectral information of the incident light being measured is obtained by solving the following matrix equations; ； Formula (1); Among them, C ij (i = 1, 2, ..., M)(j = 1, 2, ..., N) represents a center wavelength of λ. j When the refractive index of the tunable refractive index layer takes the i-th value, the light intensity I measured by the light detection unit is... ij .

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