Micro-spectrometer and spectrum detection method based on tuning mechanism

Abstract

The present invention discloses a micro-spectrometer based on a tuning mechanism and a spectrum detection method. The micro-spectrometer includes a grating structure, which is at least used to reflect, transmit or absorb light of a selected wavelength in the measured light, thereby generating at least one resonance peak; an adjustable refractive index structure, which is composed of a refractive index adjustable material, and allows the measured light to pass through and be incident on the grating structure, and the resonance peak generated by the grating structure is moved by adjusting the refractive index; a detection structure, which is at least used to absorb the light of the selected wavelength reflected or transmitted by the grating structure and generate an electrical signal, or at least used to receive the hot carriers generated by the grating structure after absorbing the light of the selected wavelength and generate an electrical signal. The present invention uses a refractive index adjustable material layer to cover a metal grating to tune the spectral response, and combined with a compressed sensing algorithm, it can achieve high-precision resolution of the original spectrum relying only on a single or a small number of light detectors.

Description

Technical Field

[0001] The present invention particularly relates to a micro-spectrometer based on a tuning mechanism and a spectrum detection method, belonging to the technical field of analytical equipment. Background Art

[0002] The spectrometer is one of the most common devices for analyzing material composition, and has important applications in optical communications, remote sensing mapping, pharmaceutical development, medical diagnosis, environmental monitoring, and agriculture and forestry. Usually, a spectrometer requires a rotatable grating and detector or a fixed grating and detector array combination to collect spectral information, so the equipment is complex, large, and expensive. Recently, a manufacturer has launched a miniature spectrometer based on a detector array and an on-chip spectrometer structure, which greatly improves the applicability of the spectrometer. However, in infrared and terahertz bands, the detector array unit is small in size and high in price, and spectrometer elements such as gratings are also very expensive.

[0003] To address this problem, a series of micro-spectrometers based on tuning mechanisms have emerged, that is, based on a single or a small number of detectors combined with a tunable response mechanism to obtain spectral information. For example, in 1999, Sensors and Actuators, Vol. 76, p. 191, reported a micro-spectrometer based on MEMs resonant cavity filter. The transmission wavelength was tuned by changing the cavity length of the resonant cavity by applying power, and the spectral information was obtained by scanning the wavelengths in sequence. In 2006, Applied Physics Letters, Vol. 89, No. 081105, reported a micro-spectrometer based on spiral ferroelectric liquid crystal. The Bragg diffraction wavelength was tuned by changing the temperature to adjust the distance between the liquid crystal molecular layers. The light intensity information was sampled in sequence and read out by the detector, and a spectral resolution of 12-25nm was obtained in the visible light band. In 2013, Optics Letters, Vol. 38, p. 4996 reported a micro-spectrometer based on liquid crystal birefringence. The phase difference between o-light and e-light was changed by changing the size of birefringence by applying pressure, thereby changing the polarization state emitted to the linear polarizer, and then tuning the fluctuation of light intensity at different wavelengths, and using compressed sensing technology to obtain spectral information. Letters, Vol. 39, p. 3923, reported a Mach-Zehnder waveguide micro-spectrometer based on lithium niobate electro-optical crystal. The transmission phase in the waveguide was tuned by changing the refractive index of lithium niobate by bias voltage, and the spectral information was obtained by Fourier transform, with a spectral resolution of less than 1nm. Laser Photonics Reviews, Vol. 9, p. 1, 2015, reported a micro-spectrometer based on MEMS structure. By controlling the MEMS moving mirror to produce a large optical path difference between the two arms of the Michael interferometer, and recording the displacement information of the moving mirror, the spectral information was obtained by Fourier transform, and a spectral resolution of 25nm was obtained in the near-infrared. Micromachines, Vol. 9, p. 478, 2018, reported a micro-spectrometer based on a rotating reflection grating. The grating was rotated to change the incident angle to tune the diffraction wavelength of a fixed output direction, and the light intensity information was sampled in sequence and read out by the detector, achieving a spectral resolution of 10nm in the near-infrared band.

[0004] However, although the above existing micro-spectrometers based on tuning mechanisms have demonstrated the function of obtaining spectral information by combining a single detector with a tuning structure, they generally have problems such as limited spectral resolution, mechanical moving parts, and low tuning efficiency. Summary of the invention

[0005] The main purpose of the present invention is to provide a micro-spectrometer and a spectrum detection method based on a tuning mechanism to overcome the deficiencies in the prior art.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0007] An embodiment of the present invention provides a micro-spectrometer based on a tuning mechanism, comprising:

[0008] A grating structure, which is used to at least reflect, transmit or absorb light of a selected wavelength in the measured light, thereby generating at least one resonance peak;

[0009] The adjustable refractive index structure is made of a material with an adjustable refractive index and can at least allow the measured light to pass through and be incident on the grating structure, and the resonance peak generated by the grating structure can be moved by adjusting the refractive index of the adjustable refractive index structure;

[0010] The detection structure is at least used to absorb the light of the selected wavelength reflected or transmitted by the grating structure and generate an electrical signal, or at least used to receive the hot carriers generated by the grating structure after absorbing the light of the selected wavelength and generate an electrical signal.

[0011] The embodiment of the present invention further provides a spectrum detection method, which is implemented based on the micro-spectrometer based on the tuning mechanism, and the spectrum detection includes:

[0012] The measured light is made to pass through the adjustable refractive index structure and then be incident on the grating structure;

[0013] The refractive index of the adjustable refractive index structure is adjusted multiple times to change the spectral components reflected, transmitted or absorbed by the grating structure, thereby changing the electrical signal output by the detection structure accordingly;

[0014] The compressed sensing algorithm is used to analyze the electrical signals output by the detection structure multiple times to obtain the spectral information of the measured light.

[0015] Compared with the prior art, the advantages of the present invention include:

[0016] 1) A micro-spectrometer based on a tuning mechanism provided by an embodiment of the present invention uses a metal grating covered with a refractive index tunable material layer to tune the spectral response, has a very large resonance wavelength tuning range, and a small surface refractive index change can obtain obvious spectral tuning, thereby obtaining enough low-correlation spectral responses, and combined with a compressed sensing algorithm, a high-precision original spectrum can be parsed;

[0017] 2) A micro-spectrometer based on a tuning mechanism provided in an embodiment of the present invention can obtain spectral responses of multiple resonance peaks by adjusting the metal grating structure, thereby improving the signal-to-noise ratio and the sampling efficiency of spectral information, realizing spectral reconstruction with a small number of samples, and reducing the volume and weight of the spectrometer;

[0018] 3) An embodiment of the present invention provides a micro-spectrometer based on a tuning mechanism, in which the metal grating can be composed of a single or multiple different grating structures, and each metal grating of a different grating structure corresponds to an independently working active material layer, thereby improving the spectral sampling efficiency and increasing the wavelength range of spectral analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to better illustrate the content of the present invention, the following is a brief description of the embodiments in conjunction with the accompanying drawings. The accompanying drawings are schematic diagrams of idealized embodiments of the present invention. For the sake of clarity, the proportions of layers and regions are magnified, but as schematic diagrams, they should not be considered to strictly reflect the proportional relationship of geometric dimensions. The embodiments shown in the present invention should not be considered to be limited to the specific shapes of the regions shown in the drawings. The representations in the drawings are schematic and should not be considered to limit the scope of the present invention. Among them:

[0020] Figure 1a and Figure 1c It is a schematic diagram of the working principle of a micro-spectrometer based on a tuning mechanism working in a transmission mode provided by a typical implementation case of the present invention;

[0021] Figure 1b is a schematic diagram of a one-dimensional periodic grating structure provided by a typical implementation example of the present invention;

[0022] Figure 1d It is a schematic diagram of the working principle of a micro-spectrometer based on a tuning mechanism working in a reflection mode provided by a typical implementation case of the present invention;

[0023] Figure 1e It is a schematic diagram of the working principle of a micro-spectrometer based on a tuning mechanism working in an absorption mode provided by a typical implementation case of the present invention;

[0024] Figure 2a It is a calculated transmission spectrum corresponding to the refractive index of different refractive index tunable material layers in a micro-spectrometer based on a tuning mechanism in a transmission mode in a typical implementation case of the present invention;

[0025] Figure 2b It is a calculated reflection spectrum corresponding to the refractive index of different refractive index tunable material layers in a micro-spectrometer based on a tuning mechanism in a reflection mode in a typical implementation case of the present invention;

[0026] Figure 2c It is a calculated absorption spectrum corresponding to the refractive index of different refractive index tunable material layers in a micro-spectrometer based on a tuning mechanism in an absorption mode in a typical implementation case of the present invention;

[0027] Figure 3A micro-spectrometer based on a tuning mechanism in a typical implementation case of the present invention works in a reflection mode, and when the refractive index of the refractive index tunable material layer is 1.4, the spatial distribution of the electric field density corresponding to the resonance peak;

[0028] Figure 4a is a schematic diagram of a metal grating with a two-dimensional periodic structure in a typical implementation case of the present invention;

[0029] Figure 4b A micro-spectrometer based on a tuning mechanism in a typical implementation case of the present invention works in a reflection mode. When the incidence is normal, the micro-spectrometer calculates the reflection spectrum under different grating structure parameters and refractive index changes of the refractive index tunable material layer;

[0030] Figure 4c It is a reflection spectrum calculated by a micro-spectrometer based on a tuning mechanism in a typical implementation case of the present invention when the micro-spectrometer works in a reflection mode and the refractive index of the refractive index tunable material layer changes under oblique incidence;

[0031] Figure 5a It is the calculated reflection spectrum corresponding to the change of the refractive index of the different refractive index tunable material layers when the metal grating with a one-dimensional periodic structure in a typical implementation case of the present invention is at normal incidence in the reflection mode;

[0032] Figure 5b It is a reconstruction result of a measured spectrum obtained based on an output signal of an active material layer and in combination with a spectrum reconstruction algorithm in a typical implementation case of the present invention;

[0033] Figure 6a It is a calculated reflection spectrum corresponding to the refractive index change of different refractive index adjustable material layers under oblique incidence of a metal grating with a two-dimensional periodic structure in a typical implementation case of the present invention in the reflection mode, wherein the period size of the grating in two directions is the same;

[0034] Figure 6b It is a reconstruction result of a measured spectrum obtained based on an output signal of an active material layer and in combination with a spectrum reconstruction algorithm in a typical implementation case of the present invention;

[0035] Figure 7a yes Figure 6a part of the reflectance spectrum;

[0036] Figure 7b It is based on the active material layer corresponding Figure 7a The measured spectrum is reconstructed from the output signal of the reflection spectrum;

[0037] Figure 8a It is a calculated reflection spectrum corresponding to the refractive index change of different refractive index tunable material layers when a metal grating with a one-dimensional periodic structure in a typical implementation case of the present invention is at normal incidence in the reflection mode.

[0038] Figure 8b It is the calculated reflection spectrum corresponding to the refractive index change of different refractive index tunable material layers of a two-dimensional periodic metal grating at normal incidence, where the period sizes of the grating in two directions are different.

[0039] Figure 8c It is the calculated reflection spectrum corresponding to the refractive index change of different refractive index adjustable material layers when the metal grating with two-dimensional periodic structure is at oblique incidence, where the period sizes of the grating in two directions are different.

[0040] Figure 8d The measured spectrum is reconstructed based on the output signal of the active material layer corresponding to the three types of reflection spectra.

[0041] Figure 9a In a typical embodiment of the present invention, in a micro-spectrometer based on a tuning mechanism, three unit structures each using a metal grating with a two-dimensional periodic structure in a reflection mode, the calculated reflection spectrum corresponding to the refractive index change of different refractive index adjustable material layers at oblique incidence;

[0042] Figure 9b In a typical implementation case of the present invention, the active material layer corresponds to Figure 9a The measured spectrum is reconstructed from the output signal of the reflection spectrum;

[0043] Fig.10 In a typical implementation case of the present invention, a micro-spectrometer based on a tuning mechanism works in the far-infrared band in the reflection mode, and the reflection spectra corresponding to the refractive index changes of different refractive index adjustable material layers are calculated. DETAILED DESCRIPTION

[0044] In view of the deficiencies in the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution, its implementation process and principle will be further explained as follows.

[0045] In view of the deficiencies in the prior art, an embodiment of the present invention provides a miniature spectrometer based on a tuning mechanism, wherein the miniature spectrometer comprises at least a beam collimator, a metal grating, a refractive index adjustable material layer and an active material layer, wherein the refractive index adjustable material layer covers the surface of the metal grating, and the measured light passes through the refractive index adjustable material layer after passing through the beam collimator and is incident on the metal grating. By adjusting the refractive index of the refractive index adjustable material layer, the spectral components of the reflection, transmission or absorption of the metal grating can be changed, thereby changing the photoelectric conversion signal output by the active material layer. The output signal of the active material layer corresponding to multiple adjustments is combined with a compressed sensing algorithm to parse the spectral information of the measured light.

[0046] The embodiment of the present invention provides a metal grating in a micro-spectrometer based on a tuning mechanism, which can excite surface plasma resonance of the electromagnetic field distribution domain on the surface of the metal grating under light. The metal grating has extremely high surface refractive index sensitivity. Therefore, a slight change in the surface refractive index can obtain obvious tuning of the reflection, transmission and absorption spectra, thereby obtaining a sufficient number of low-correlation spectral responses, which is very beneficial for the compressed sensing algorithm to parse the high-precision original spectrum.

[0047] An embodiment of the present invention provides a micro-spectrometer based on a tuning mechanism, comprising:

[0048] A grating structure, which is used to at least reflect, transmit or absorb light of a selected wavelength in the measured light, thereby generating at least one resonance peak;

[0049] The adjustable refractive index structure is made of a material with an adjustable refractive index and can at least allow the measured light to pass through and be incident on the grating structure, and the resonance peak generated by the grating structure can be moved by adjusting the refractive index of the adjustable refractive index structure;

[0050] The detection structure is at least used to absorb the light of the selected wavelength reflected or transmitted by the grating structure and generate an electrical signal, or at least used to receive the hot carriers generated by the grating structure after absorbing the light of the selected wavelength and generate an electrical signal.

[0051] Furthermore, the grating structure is capable of reflecting, transmitting or absorbing light of a selected wavelength in the measured light within a specified wavelength band.

[0052] Furthermore, the adjustable refractive index structure is coated on a first surface of the grating structure, and the first surface of the grating structure faces the light source.

[0053] Furthermore, the adjustable refractive index structure includes a refractive index adjustable material layer.

[0054] Furthermore, the manner of adjusting the refractive index of the adjustable refractive index structure includes electrical excitation, thermal excitation or optical excitation, but is not limited thereto.

[0055] Furthermore, there are one or more grating structures, and each of the grating structures corresponds to an independently working detection structure, that is, each metal grating of a different grating structure corresponds to an independently working active material layer.

[0056] In some more specific implementations, the grating structure is a one-dimensional periodic grating structure, or the grating structure is a two-dimensional periodic grating structure, and the grating structure has relatively independent periodic parameters in two orthogonal x and y directions.

[0057] Furthermore, the height of the grating structure is less than one tenth of the selected wavelength.

[0058] Furthermore, the grating structure is a metal grating.

[0059] Furthermore, the grating structure includes a continuous metal film.

[0060] Specifically, the metal grating can allow the measured light within one or more wavelength ranges to be reflected or transmitted to the active material layer, while the measured light in the remaining wavelength ranges is absorbed or irradiated outside the active material layer. The material of the metal grating includes at least one of gold, platinum, silver, copper, aluminum and titanium, but is not limited thereto.

[0061] Specifically, the wavelength of the reflected light, transmitted light or absorbed light generated by the metal grating is mainly determined by the metal grating period, the incident angle and the refractive index of the metal grating surface. By adjusting these parameters, the wavelength range of the reflected or transmitted light can be tuned to various bands.

[0062] Further, the detection structure is arranged on a second surface of the grating structure, and the second surface is arranged opposite to the first surface, or the detection structure is arranged on a side of the adjustable refractive index structure opposite to the grating structure.

[0063] Furthermore, the detection structure includes an active material layer capable of converting optical signals into electrical signals.

[0064] Furthermore, the micro-spectrometer based on the tuning mechanism also includes: a beam collimator, which is at least used to collimate the measured light emitted by the light source and then make it incident on the adjustable refractive index structure.

[0065] The embodiment of the present invention further provides a spectrum detection method, which is implemented based on the micro-spectrometer based on the tuning mechanism, and the spectrum detection includes:

[0066] The measured light is made to pass through the adjustable refractive index structure and then be incident on the grating structure;

[0067] The refractive index of the adjustable refractive index structure is adjusted multiple times to change the spectral components reflected, transmitted or absorbed by the grating structure, thereby changing the electrical signal output by the detection structure accordingly;

[0068] The compressed sensing algorithm is used to analyze the electrical signals output by the detection structure multiple times to obtain the spectral information of the measured light.

[0069] Furthermore, the spectrum detection method specifically includes: adjusting the refractive index of the adjustable refractive index structure by electrical excitation, thermal excitation or optical excitation.

[0070] Furthermore, the spectral detection method also includes: tuning the wavelength range in which the grating structure allows reflection, transmission or absorption of light to a desired band by adjusting at least one operating parameter of the grating structure, wherein the operating parameters of the grating structure include a grating period, an incident angle or a grating surface refractive index.

[0071] The technical solution, its implementation process and principle will be further explained below in conjunction with the accompanying drawings. Unless otherwise specified, the metal grating, refractive index tunable material layer, active material layer, etc. that constitute a micro-spectrometer provided in an embodiment of the present invention can all be those known to those skilled in the art.

[0072] Please refer to Figure 1. An embodiment of the present invention provides a micro-spectrometer based on a tuning mechanism, which at least includes an active material layer 1, a metal grating 2, a refractive index adjustable material layer 3 and a beam collimator 4, wherein the refractive index adjustable material layer 3 covers the surface of the metal grating 2. By adjusting the refractive index of the refractive index adjustable material layer 3, the spectral components of the reflection, transmission or absorption of the metal grating can be changed, thereby changing the photoelectric conversion signal output by the active material layer 1. The output signal of the active material layer 1 obtained by multiple adjustments is combined with a compressed sensing algorithm to parse the spectral information of the measured light.

[0073] The micro-spectrometer based on the tuning mechanism provided by the embodiment of the present invention has a transmission mode ( Figure 1a , Figure 1c ), Reflection Mode( Figure 1d ) and absorption mode ( Figure 1e )Three working modes:

[0074] In the transmission mode, the measured light passes through the refractive index tunable material layer 3 and the metal grating 2, and the transmitted light is absorbed by the active material layer 1 to form an electrical signal;

[0075] In the reflection mode, the measured light passes through the refractive index tunable material layer 3 and is reflected by the metal grating 2, and the reflected light is absorbed by the active material layer 1 to form an electrical signal;

[0076] In the absorption mode, the measured light passes through the refractive index tunable material layer 3, and the transmitted light is absorbed by the metal grating 2 to form hot carriers, which are then injected into the active material layer 1 to form electrical signals.

[0077] The technical solution of the present invention will be described in detail below in conjunction with several preferred embodiments and related drawings.

[0078] Example 1

[0079] See also Figure 1aIn this embodiment, a micro-spectrometer based on a tuning mechanism works in a transmission mode and operates in a near-infrared band. The micro-spectrometer based on a tuning mechanism includes an active material layer 1, a metal grating 2, a refractive index tunable material layer 3 and a beam collimator 4; Figure 1b As shown, the metal grating 2 adopts a one-dimensional periodic grating and is in direct contact with the active material layer 1. The incident light beam 5 is incident on the refractive index adjustable material layer 3 via the beam collimator 4 and passes through the refractive index adjustable material layer 3 and the metal grating 2 in sequence. The transmitted light passing through the refractive index adjustable material layer 3 and the metal grating 2 is absorbed by the active material layer 1 to form an electrical signal output.

[0080] Specifically, incident light beams of different wavelengths are coupled with the surface plasmon waves of the metal grating 2 at specific incident angles, and the coupling condition is determined by the following formula:

[0081] n 0 sinθ+mG=±k sp

[0082] Among them, k 0 is the vacuum wave vector, n is the refractive index of the refractive index tunable material layer, θ is the incident angle on the surface of the metal grating 2, G = 2π / Λ is the lattice vector of the metal grating 2, Λ is the period of the metal grating 2, m is the diffraction order, k sp is the wave vector of the metal surface plasma wave.

[0083] See also Figure 2a The material of the active material layer 1 includes silicon, the period of the metal grating 2 is 1 μm, the width is 0.6 μm, and the height is 50 nm. The thickness of the gold material layer covering the surface of the metal grating 2 is 40 nm.

[0084] Assuming that the refractive index tunable material layer 3 covers the upper surface space of the metal grating 2, when the refractive index of the refractive index tunable material layer 3 changes, the transmission peak wavelength in the transmission spectrum changes; for example, when the refractive index of the refractive index tunable material layer 3 changes from 1.4 to 1.2, the transmission peak wavelength blue-shifts from 1.42 μm to 1.22 μm.

[0085] Example 2

[0086] See also Figure 1cIn this embodiment, a working mode of a micro-spectrometer based on a tuning mechanism is a transmission mode. The micro-spectrometer based on the tuning mechanism includes an active material layer 1, a metal grating 2, a refractive index adjustable material layer 3 and a beam collimator 4. The metal grating 2 adopts a one-dimensional periodic grating. The material of the metal grating 2 is gold. The active material layer 1 is not in direct contact with the metal grating 2. The active material layer 1 can be a material layer of a discrete detection structure; the incident light beam 5 is incident on the refractive index adjustable material layer 3 via the beam collimator 4, and the transmitted light passing through the refractive index adjustable material layer 3 and the metal grating 2 is absorbed by the active material layer 1 to form an electrical signal output.

[0087] Example 3

[0088] See also Figure 1d In this embodiment, a micro-spectrometer based on a tuning mechanism works in a transmission mode and works in the terahertz band; the micro-spectrometer based on the tuning mechanism includes an active material layer 1, a metal grating 2, a refractive index adjustable material layer 3 and a beam collimator 4, the material of the metal grating 2 is gold, and the metal grating 2 adopts a one-dimensional periodic grating; the incident light beam 5 is incident on the refractive index adjustable material layer 3 via the beam collimator 4, passes through the refractive index adjustable material layer 3 and is reflected by the metal grating 2, and the reflected light beam 6 is emitted again via the refractive index adjustable material layer 3, and is finally received by the active material layer 1 to form an electrical signal.

[0089] See also Figure 2b , the period of the metal grating 2 is 140 μm, the width is 116 μm, the height is 5.5 μm, and the thickness of the gold material layer covering the surface of the metal grating 2 is 200 nm; assuming that the refractive index adjustable material layer 3 covers the surface space of the metal grating 2, when the refractive index of the refractive index adjustable material layer 3 changes, the reflection peak wavelength in the reflection spectrum changes; for example, when the refractive index of the refractive index adjustable material layer 3 changes from 1.4 to 1.2, the reflection peak frequency moves from 1.525 THz to 1.779 THz; and when the refractive index of the refractive index adjustable material layer 3 is 1.4, the electric field density space distribution corresponding to the reflection peak 1.525 THz is as follows Figure 3 As shown, from Figure 3 It can be seen that most of the electric field is localized on the surface of the metal grating 2, which greatly enhances the effect of the electromagnetic field and the refractive index tunable material layer 3, thereby increasing the movement of the reflection peak under the same refractive index change.

[0090] Example 4

[0091] See also Figure 1eIn this embodiment, a micro-spectrometer based on a tuning mechanism works in an absorption mode and operates in a near-infrared band; the micro-spectrometer based on a tuning mechanism includes an active material layer 1, a metal grating 2, a refractive index tunable material layer 3 and a beam collimator 4; an incident light beam 5 is incident on the refractive index tunable material layer 3 via the beam collimator 4, and the measured light passes through the refractive index tunable material layer 3 and is absorbed by the metal grating 2 to form hot carriers, and the hot carriers are injected into the active material layer 1 and form electrical signals.

[0092] Specifically, the material of the active material layer 1 includes silicon, the material of the metal grating 2 is gold, and it is a one-dimensional periodic grating structure, the period of the metal grating 2 is 1 μm, the width is 0.6 μm, and the height is 50 nm. The thickness of the gold material layer covering the surface of the metal grating 2 is 100 nm, and the refractive index adjustable material layer 3 covers the upper surface of the metal grating 2; Figure 2c As shown, the absorption spectrum has a resonance peak with a narrow line width and shifts as the refractive index of the refractive index tunable material layer 3 changes.

[0093] Example 5

[0094] The metal gratings in the above embodiments all adopt a one-dimensional periodic grating structure, generating a resonance peak in the detection band.

[0095] Different from the embodiments 1-4, the metal grating in this embodiment is a two-dimensional periodic grating structure, and the periods of the metal grating in the orthogonal x and y directions are different, such as Figure 4a As shown, the material of the metal grating 2 is gold, the period in the x direction Λx = 190μm, the period in the y direction Λy = 210μm, the width of the grating in the x direction Wgx = 160μm, the width of the grating in the y direction Wgy = 176μm, the height of the metal grating 2 is 6μm, and the thickness of the gold material layer covering the surface of the metal grating 2 is 200nm; the refractive index adjustable material layer 1 is liquid crystal, and the thickness is 40μm.

[0096] In this embodiment, a micro-spectrometer based on a tuning mechanism operates in a reflection mode and operates in the terahertz band; Figure 4bAs shown, when the incident light beam is incident normally, the two-dimensional periodic grating structure generates two reflection peaks, and when the refractive index of the refractive index adjustable material layer 3 is fixed, by changing the period of the metal grating in the x or y direction respectively, the frequency position of a resonance peak in the reflection spectrum can be independently adjusted. For example, the period in the x direction is fixed to 190 μm, and the period in the y direction is taken as 210 μm, 226 μm and 250 μm respectively. At this time, the grating structure in the x direction corresponding to the reflection peak of 1.29 THz remains unchanged, while the reflection peaks corresponding to the grating structure in the y direction are 1.2 THz, 1.1 THz and 1.05 THz respectively; and when the refractive index of the refractive index adjustable material layer is adjusted from 1.58 to 1.8, the reflection peak frequencies corresponding to the grating structures in both directions change.

[0097] Example 6

[0098] The working mode of a micro-spectrometer based on a tuning mechanism in this embodiment is a reflection mode and operates in the terahertz band. Similar to Embodiment 4, this embodiment also adopts a two-dimensional periodic grating structure. The difference is that the incident light (beam) in this embodiment is obliquely incident, so four reflection peaks are generated, such as Figure 4c As shown; the material of the metal grating is gold, the period of the metal grating in the x direction Λx = 190μm, the period in the y direction Λy = 230μm, the width of the grating in the x direction Wgx = 164μm, the width of the grating in the y direction Wgy = 198μm, the height of the metal grating 2 is 6μm, the thickness of the gold material layer covering the surface of the metal grating 2 is 200nm, the refractive index adjustable material layer 3 uses liquid crystal, has a thickness of 40μm, and an incident angle of 5°; when the refractive index of the refractive index adjustable material layer changes from 1.58 to 1.8, the frequencies of the four reflection peaks all change.

[0099] Example 7

[0100] See also Figure 1d In this embodiment, a working mode of a micro-spectrometer based on a tuning mechanism is a reflection mode, and operates in the terahertz band; the material of the metal grating is gold, and it is a one-dimensional periodic grating structure, the period of the metal grating is 210μm, the width is 176μm, and the height is 6μm, and the material of the adjustable refractive index layer 3 is liquid crystal, and the thickness is 40μm.

[0101] like Figure 5a As shown in Figure 1, when the refractive index of the liquid crystal changes from 1.58 to 1.8, the frequency of the reflection peak changes from 1.23 THz to 1.14 THz, and the reflected wave energy is converted into an electrical signal output by the active material layer; when the refractive index of the liquid crystal changes between 1.58 and 1.8, the electrical signals corresponding to 25 and 50 different values ​​are taken respectively. Figure 5aThe spectral information of the incident light can be reconstructed by combining the compressed sensing algorithm; Figure 5b As shown, taking the electrical signals corresponding to 50 changes in the refractive index of the liquid crystal (ie, 50 samples) for spectrum reconstruction can obtain a result that is almost completely consistent with the original spectrum of the incident light.

[0102] Example 8

[0103] See also Figure 4a In this embodiment, a micro-spectrometer based on a tuning mechanism works in a reflection mode and operates in the terahertz band; the material of the metal grating 2 is gold material, and it is a two-dimensional periodic grating structure, and the period in the x and y directions is 210μm, the width of the metal grating 2 is 176μm, and the height is 6μm. The material of the adjustable refractive index layer 3 is liquid crystal, the thickness is 40μm, and the incident angle of the incident light is 4°.

[0104] like Figure 6a As shown, the reflection spectrum is compared with the one-dimensional periodic grating structure, the incident light is normal incident ( Figure 5a ) has two more reflection peaks, and the frequency changes from 1.14 THz to 1.23 THz; the reflected wave energy is converted into electrical signal output by the active material layer; when the refractive index of the liquid crystal changes between 1.58 and 1.8, the electrical signals corresponding to 25 and 15 different values ​​are taken respectively, and the incident light spectrum can be reconstructed based on the spectral information of Figure 6a and combined with the compressed sensing algorithm; Figure 6b As shown, by taking 25 changes in the liquid crystal refractive index (i.e., 25 samples) of the electrical signal corresponding to the changes in the refractive index of the liquid crystal for spectral reconstruction, a result that is almost completely consistent with the original spectrum of the incident light can be obtained; the reduction in the number of sampling times here comes from the newly added reflection peak, that is, at the same liquid crystal adjustable refractive index value, the metal grating can sample the incident light at more frequency points.

[0105] Example 9

[0106] In this embodiment, a working mode of the micro-spectrometer based on the tuning mechanism is a reflection mode (such as Figure 4a ), and operates in the terahertz band; the metal grating is made of gold material and is a two-dimensional periodic grating structure. The periods in the x and y directions are 218μm and 220μm respectively, the widths of the metal grating are 174μm and 176μm respectively, and the heights are both 6μm. The material of the adjustable refractive index layer 3 is liquid crystal, with a thickness of 40μm and an incident angle of 3.0°.

[0107] like Figure 7a As shown, the reflection spectrum is compared with the result of the normal incidence one-dimensional grating structure ( Figure 5a) has two more reflection peaks, and the reflected wave energy is converted into electrical signal output by the active material layer. When the refractive index of the liquid crystal changes between 1.58 and 1.8, the electrical signals corresponding to 25 different values ​​are taken. Figure 7a The spectral information of the incident light can be reconstructed by combining the compressed sensing algorithm; Figure 7b As shown, by taking 25 electrical signals corresponding to the changes in the liquid crystal refractive index (i.e., 20 samples) for spectral reconstruction, a result that is almost completely consistent with the original spectrum of the incident light can be obtained, achieving effective resolution of two reflection peaks with an interval of 0.1 GHz.

[0108] Comparing the results of the three different structures of Example 1, Example 6 and Example 7, the refractive index tunable material liquid crystal is limited to change in the range of 1.58 to 1.8, and the spectrum results are shown in Figure 8 (ac):

[0109] First, the metal grating is made of gold material and has a one-dimensional periodic grating structure. The period of the metal grating is 210 μm, the width is 176 μm, and the height is 6 μm. The material of the adjustable refractive index layer 3 is liquid crystal with a thickness of 40 μm. The incident light is incident vertically, and the corresponding reflection spectrum is as follows: Figure 8a As shown, its reflectance spectrum contains only one peak;

[0110] Secondly, the metal grating is made of gold material and is a two-dimensional periodic grating structure. The periods in the x and y directions are 210μm and 226μm respectively. The width of the metal grating is 176μm and the height is 6μm. The material of the adjustable refractive index layer 3 is liquid crystal with a thickness of 40μm. The incident light is incident vertically. The corresponding reflection spectrum is as follows: Figure 8b As shown, its reflection spectrum is compared with the one-dimensional periodic grating structure ( Figure 8a ) has one more reflection peak;

[0111] Third, the metal grating is made of gold material and is a two-dimensional periodic grating structure. The periods in the x and y directions are 190 μm and 230 μm respectively. The widths of the metal grating are 164 μm and 198 μm respectively, and the heights are both 6 μm. The material of the adjustable refractive index layer 3 is liquid crystal with a thickness of 40 μm. The incident angle is 5.0°. The corresponding reflection spectrum is as follows: Figure 8c As shown, its reflection spectrum is compared with the two-dimensional periodic grating structure ( Figure 8b ) has two more reflection peaks;

[0112] For each case, 45 signals converted by the active material layer are selected for spectrum reconstruction using compressed sensing. Figure 8d As shown, it can be seen that Figure 8c The spectral reconstruction accuracy is higher, which is due to the fact that the reflection peak of the spectrum in Example 6 covers a larger frequency range.

[0113] Example 10

[0114] In this embodiment, a working mode of the micro-spectrometer based on the tuning mechanism is a reflection mode (such as Figure 4a ), and operates in the terahertz band, and adopts three unit structures at the same time, each unit structure covers a spectral range, and a spectral analysis function with a larger range is obtained by splicing the reconstructed spectra corresponding to the three unit structures. The micro-spectrometers in the above embodiments all adopt a grating structure, and the spectrum of the resonance peak generated by the grating is changed by adjusting the adjustable refractive index material layer; this embodiment adopts three grating structures, and the spectrum of the resonance peak generated by the grating is also changed by adjusting the adjustable refractive index material layer.

[0115] Specifically, for the first unit structure: the metal grating is made of gold material and is a two-dimensional periodic grating structure, the periods in the x and y directions are 120 μm and 138 μm respectively, the widths of the metal grating are 96 μm and 110 μm respectively, and the heights are both 6 μm, the material of the adjustable refractive index layer 3 is liquid crystal, the thickness is 40 μm, and the incident angle is 14.0°;

[0116] For the second unit structure: the metal grating is made of gold material and is a two-dimensional periodic grating structure, the periods in the x and y directions are 194 μm and 210 μm respectively, the widths of the metal grating are 155 μm and 168 μm respectively, and the heights are both 6 μm, the material of the adjustable refractive index layer 3 is liquid crystal, the thickness is 40 μm, and the incident angle is 14.0°;

[0117] For the third unit structure: the metal grating is made of gold material and is a two-dimensional periodic grating structure, the periods in the x and y directions are 226 μm and 240 μm respectively, the widths of the metal grating are 180 μm and 192 μm respectively, and the heights are both 6 μm, the material of the adjustable refractive index layer 3 is liquid crystal, the thickness is 40 μm, and the incident angle is 14.0°;

[0118] The refractive index of the tunable material liquid crystal is limited to change in the range of 1.58 to 1.8, and its spectrum results are as follows Figure 9a As shown, the spectral adjustable range can be close to 1 terahertz; 20 signals converted by the active material layer are selected from the spectrum of the embodiment for compressed sensing spectral reconstruction as shown in Figure 9b As shown, the frequency range covered by the reconfigurable reflection peak is also close to 1 THz.

[0119] Embodiment 11

[0120] In this embodiment, a working mode of the micro-spectrometer based on the tuning mechanism is a reflection mode (such as Figure 1d), and operates in the mid-infrared band, the metal grating is made of gold, the period of the metal grating is 10.55μm, the width is 9.6μm, the height is 460nm, the thickness of the gold material layer covered on the surface of the metal grating 2 is 200nm, and the reflection spectrum corresponding to changing the refractive index of the refractive index adjustable material layer 3 is as follows Fig.10 shown.

[0121] A micro-spectrometer based on a tuning mechanism provided by an embodiment of the present invention uses a metal grating covered with a refractive index tunable material layer to tune the spectral response. It has a very large resonance wavelength tuning range, and a slight change in the surface refractive index can obtain obvious spectral tuning, thereby obtaining a sufficient number of low-correlation spectral responses. The present invention only needs a single or a few detectors and combines them with a compressed sensing algorithm to parse out a high-precision original spectrum.

[0122] A metal grating in a micro-spectrometer based on a tuning mechanism provided by an embodiment of the present invention can excite a resonance mode under light. The electromagnetic field in the resonance mode is distributed on the surface of the metal grating. Therefore, when the adjustable refractive index structure changes its refractive index, it will cause a huge change in the electromagnetic field distribution, thereby causing the resonance peak generated by the grating structure to move more significantly.

[0123] A micro-spectrometer based on a tuning mechanism provided by an embodiment of the present invention can obtain spectral responses of multiple resonance peaks by adjusting the metal grating structure, thereby improving the signal-to-noise ratio and the sampling efficiency of spectral information, realizing spectral reconstruction with a small number of samples, and reducing the volume and weight of the spectrometer.

[0124] An embodiment of the present invention provides a micro-spectrometer based on a tuning mechanism, in which the metal grating can be composed of a single or multiple different grating structures, and each metal grating of a different grating structure corresponds to an independently working active material layer, thereby improving the spectral sampling efficiency and increasing the wavelength range of spectral analysis.

[0125] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A micro-spectrometer based on a tuning mechanism, characterized in that include: A grating structure, which is at least used to reflect, transmit or absorb light of a selected wavelength in the measured light, thereby generating at least one resonance peak, and the grating structure is a metal grating structure; An adjustable refractive index structure, the adjustable refractive index structure is covered on the first surface of the grating structure, the first surface of the grating structure faces the light source, the adjustable refractive index structure is made of a material with adjustable refractive index, and allows the measured light to pass through and be incident on the grating structure, and the resonant peak generated by the grating structure can be moved by adjusting the refractive index of the adjustable refractive index structure; The detection structure is at least used to absorb the light of the selected wavelength reflected or transmitted by the grating structure and generate an electrical signal, or at least used to receive the hot carriers generated by the grating structure after absorbing the light of the selected wavelength and generate an electrical signal.

2. The micro-spectrometer based on the tuning mechanism according to claim 1, characterized in that: The grating structure can realize one or more reflections, transmissions or absorptions of light of selected wavelengths in the measured light within a specified wavelength band.

3. The micro-spectrometer based on the tuning mechanism according to claim 1, characterized in that: The adjustable refractive index structure includes a refractive index adjustable material layer.

4. The micro-spectrometer based on the tuning mechanism according to claim 3, characterized in that: The refractive index of the adjustable refractive index structure can be adjusted by electrical excitation, thermal excitation or optical excitation.

5. The micro-spectrometer based on the tuning mechanism according to claim 1, characterized in that: There are one or more grating structures, and each of the grating structures corresponds to an independently working detection structure.

6. The micro-spectrometer based on the tuning mechanism according to claim 1 or 5, characterized in that: The grating structure is a one-dimensional periodic grating structure; or, the grating structure is a two-dimensional periodic grating structure, and the grating structure has relatively independent periodic parameters in two orthogonal x and y directions.

7. The micro-spectrometer based on the tuning mechanism according to claim 6, characterized in that: The height of the grating structure is less than one tenth of the selected wavelength.

8. The micro-spectrometer based on the tuning mechanism according to claim 6, characterized in that: The grating structure includes a continuous metal film.

9. The micro-spectrometer based on the tuning mechanism according to claim 3, characterized in that: The detection structure is arranged on the second surface of the grating structure, and the second surface is arranged opposite to the first surface, or the detection structure is arranged on a side of the adjustable refractive index structure opposite to the grating structure.

10. The micro-spectrometer based on the tuning mechanism according to claim 9, characterized in that: The detection structure includes an active material layer capable of converting an optical signal into an electrical signal.

11. The micro-spectrometer based on the tuning mechanism according to claim 10, characterized in that: The material of the active material layer includes photoelectric material and / or photothermoelectric material.

12. The micro-spectrometer based on the tuning mechanism according to claim 1, characterized in that Also includes: The beam collimator is at least used to collimate the measured light emitted by the light source and then allow it to enter the adjustable refractive index structure.

13. A spectrum detection method, characterized in that: The spectral detection method is implemented based on the micro-spectrometer based on the tuning mechanism according to any one of claims 1 to 12, and the spectral detection method comprises: The measured light is made to pass through the adjustable refractive index structure and then be incident on the grating structure; The refractive index of the adjustable refractive index structure is adjusted multiple times to change the spectral components reflected, transmitted or absorbed by the grating structure, thereby changing the electrical signal output by the detection structure accordingly; The compressed sensing algorithm is used to analyze the electrical signals output multiple times by the detection structure to obtain the spectral information of the measured light.

14. The spectrum detection method according to claim 13, characterized in that Specifically include: The refractive index of the tunable refractive index structure is adjusted by electrical excitation, thermal excitation or optical excitation.

15. The spectrum detection method according to claim 13, characterized in that Also includes: The wavelength range of light that the grating structure allows to reflect, transmit or absorb is tuned to a desired wavelength band by adjusting at least one or more operating parameters of the grating structure, wherein the operating parameters of the grating structure include grating period, light source incident angle or grating surface refractive index.

Images