A resolution customizable miniature spectrometer based on transverse dispersion metasurface

Abstract

The application discloses a resolution customizable miniature spectrometer based on a transverse dispersion super surface, which comprises a dispersion super surface array structure and a focal plane pixel array, wherein the dispersion super surface array structure comprises a plurality of array distributed dispersion super surface subarrays for preliminary spectral decoupling and directional convergence; the dispersion super surface subarray comprises a plurality of dispersion super surface units and a whole medium substrate thereof; the dispersion super surface unit is a nano column with four-fold symmetry; the nano columns are periodically arranged; the transmission light phase is dynamically controlled according to the incident light frequency omega, so that the focal point position (x', y') of the transmission light on the focal plane is linearly mapped with the change of omega; and the focal plane pixel array comprises a multi-element plane array composed of a plurality of pixels, which is pixel level registered with the dispersion super surface subarray. The application realizes accurate light condensation at the pixel level, effectively suppresses crosstalk, improves detection accuracy and realizes real snapshot spectral imaging.

Description

Technical Field

[0001] This invention belongs to the fields of nanophotonics and spectrometer technology, specifically relating to a micro spectrometer with customizable resolution based on a transversely dispersive metasurface. Background Technology

[0002] Spectrometers, by establishing the relationship between response and wavelength, can decompose complex spectra and obtain the relative intensity of each wavelength component, finding wide application in astronomy, biomedicine, materials characterization, and chemical analysis. Traditional spectrometers typically achieve spectral dispersion using prisms or gratings. While this achieves high spectral resolution, it also results in drawbacks such as large size, high cost, and difficulty in integration, significantly limiting its application in areas like chip-level integration.

[0003] With the rapid development of nanophotonics, metasurfaces, as a novel type of micro / nano optical field manipulation device, can precisely control the amplitude, phase, and polarization parameters of light waves. They offer advantages such as lightweight design, ease of integration, and high design freedom, and have applications in many fields, including target detection, holography, optical communication, and computing. Applying metasurfaces to the design of spectrometers can enable miniature spectrometers with smaller footprints and better chip-level integration. Currently, common metasurface-based miniature spectrometers mainly include narrowband filter spectrometers and axial dispersive spectrometers.

[0004] Narrowband filter spectrometers based on metasurfaces allow light to pass through only a specific narrow wavelength range, while other wavelengths are absorbed or reflected. Although this design can optimize peak transmittance to a high value, the average transmittance across the entire band remains low, resulting in low average energy efficiency. Axial dispersive spectrometers disperse incident light along the optical axis, with the axial intensity distribution inversely proportional to the incident wavelength. While this can improve spectral resolution and energy efficiency, it cannot capture all spectral information in a single snapshot, sacrificing temporal resolution.

[0005] Therefore, how to solve the problem of the difficulty in synergistically optimizing spectral resolution, energy utilization and temporal resolution in the existing technology, and how to provide a spectrometer design with low crosstalk without sacrificing temporal resolution are technical problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to address the problem in existing technologies that it is difficult to simultaneously achieve high spectral resolution, high energy efficiency, and temporal resolution, by providing a micro-spectrometer design based on a transversely dispersive metasurface with customizable resolution.

[0007] Therefore, the above-mentioned objectives of the present invention are achieved through the following technical solutions:

[0008] A micro-spectrometer with customizable resolution based on a transversely dispersive metasurface includes a dispersive metasurface array structure and a focal plane pixel array.

[0009] The dispersive metasurface array structure includes several arrayed dispersive metasurface subarrays and its all-dielectric substrate for preliminary spectral decoupling and directional focusing. The dispersive metasurface subarrays include several dispersive metasurface units, which are nanopillars with four-fold symmetry. Each nanopillar is periodically arranged, and the phase of the transmitted light is dynamically adjusted according to the incident light frequency ω, so that the focal position (x', y') of the transmitted light on the focal plane changes linearly with ω, thereby achieving customizable resolution.

[0010] The focal plane pixel array comprises a multi-dimensional planar array of several pixels, which is pixel-level registered with the dispersive metasurface subarray to record the spatial intensity distribution of light at different frequencies.

[0011] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0012] As a preferred embodiment of the present invention: the spatial distribution of the phase of the dispersive metasurface units in each dispersive metasurface subarray is as follows:

[0013] φ(x,y,ω)= +C(ω)

[0014] Where ω is the incident light frequency, F is the target focal length, c is the speed of light, (x,y) are the spatial coordinates on the metasurface, (x',y') is the spatial position of the transmitted light with frequency ω at the focal plane, θ represents the angle between the projection of the incident light onto the xz plane and the z-axis, γ represents the angle between the projection of the incident light onto the yz plane and the z-axis, and C(ω) is a function that depends only on frequency.

[0015] As a preferred technical solution of the present invention: the spatial position (x', y') of the transmitted light at the focal point of the focal plane is determined by the frequency of the transmitted light, where x'=m1c / ω+n1, y'=m2c / ω+n2, m1, m2 and n1, n2 are constants independent of wavelength, and the focal position of each wavelength in the working band is adjusted by changing the values ​​of m1, m2 and n1, n2.

[0016] As a preferred technical solution of the present invention: the dispersive metasurface array structure includes an all-dielectric substrate and a dispersive metasurface subarray distributed on the all-dielectric substrate. The dispersive metasurface subarrays have the same spectral dispersion capability, and the focal positions of the spectral convergence of different dispersive metasurface subarrays are uniformly moved.

[0017] As a preferred technical solution of the present invention: For each dispersive metasurface subarray with diameter D, light with frequency λ having an arbitrary polarization state, where λ is within the working wavelength band (λmin, λmax), is incident at a fixed angle θ. Since the dispersive metasurface unit has different phase modulation results for incident light of different wavelengths, the outgoing light after passing through the dispersive metasurface unit is focused at the focal plane (m1λ+n1, m2λ+n2) with focal length F, where m1, m2 and n1, n2 are constants with wavelengths independent of light, and the focal distance between the two limiting wavelengths is Δr. 2 =Δx 2 +Δy 2 Δx=m1(λ max -λ min ), Δy=m2(λ max -λ min Finally, the detector receives the light signal from the focal plane.

[0018] As a preferred technical solution of the present invention: by keeping m1=m2 and uniformly changing the size of n1 and n2, a series of dispersive metasurface subarrays with the same dispersion but uniformly shifted focal positions can be obtained. By constructing them into a dispersive metasurface array structure, different intensity distributions of the same spectral information can be detected at the focal plane. The spectral resolution can be further customized through simple calculations.

[0019] As a preferred technical solution of the present invention: the dispersive metasurface subarray is formed by micro-nano fabrication to form a nano-scale nanopillar array, and each nanopillar in the nanopillar array adopts an isotropic structure; by changing only the geometry of the nanopillars without changing their spatial orientation, the transmission phase can be controlled.

[0020] As a preferred technical solution of the present invention: the nanopillar material can be silicon, silicon nitride, or titanium dioxide;

[0021] As a preferred embodiment of the present invention: the cross-section of the nanopillar is square, the height of the nanopillar is h=4.5 micrometers, the base period is p=1.65 micrometers, the outer side length of the square is 1.0-1.4 micrometers, and the inner ring side length is 0.4-0.8 micrometers.

[0022] As a preferred embodiment of the present invention, the cross-section of the nanopillar is shaped like a star.

[0023] Compared with existing technologies, the present invention provides a micro-spectrometer with customizable resolution based on a transversely dispersive metasurface, offering the following advantages: Utilizing a pixel-level polarization-insensitive dispersive metasurface, the precise control of the incident light phase solves the problems of large size, low efficiency, and slow speed caused by traditional spectral detection systems relying on mechanical scanning or complex dispersive elements, achieving snapshot-style high-precision spectral imaging. Through customized dispersive metasurface subarrays and precise registration with the focal plane array, light of different wavelengths is directionally focused onto corresponding pixels. Combined with a simple spectral reconstruction algorithm, this achieves high energy utilization, low crosstalk, and fast response, while also possessing the advantages of compact structure and customizable resolution, providing an efficient and reliable miniaturized solution for portable spectral detection.

[0024] The spectral decoupling technology of the dispersive metasurface of this invention overcomes the inherent limitations of traditional filter-type spectrometers, achieving performance improvement through the use of a spectroscopic mode. By precisely controlling the phase of the incident light, different wavelengths of light signals are efficiently decoupled, significantly improving energy utilization efficiency and minimizing light energy loss. Through the design of a precise metaatomic structure array, the incident light is efficiently focused onto the target pixel, reducing crosstalk between adjacent pixels and greatly improving the accuracy and reliability of spectral detection. The use of lateral dispersion control allows the system to complete full-spectrum detection without mechanical scanning, shortening the response time to the microsecond level, truly achieving snapshot-style spectral imaging. In this invention, combined with a high-performance detector, complete spectral cubic data can be acquired in a single exposure, providing a novel technical solution for real-time dynamic monitoring, with broad application prospects in multiple fields such as photonics communication, satellite remote sensing, biomedicine, environmental monitoring, and materials analysis. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a micro spectrometer structure with customizable resolution based on a transversely dispersive metasurface according to the present invention.

[0026] Figure 2 This is a side view of a resolution-customizable micro-spectrometer based on a transversely dispersive metasurface according to the present invention.

[0027] Figure 3 This is a schematic diagram of the cross-sections of the three types of four-fold symmetric nanopillars used in this invention;

[0028] Figure 4 The x-coordinate of the converged light spot of the transmitted light through the metasurface in this invention varies with wavelength;

[0029] Figure 5 The focusing efficiency of the converged light spot of the transmitted light through the metasurface in this invention varies with wavelength;

[0030] In the attached figure, there is a dispersive metasurface array structure 1; a dispersive metasurface subarray 101; an all-dielectric substrate 102; a focal plane pixel array 2; and a pixel 202. Detailed Implementation

[0031] The implementation method, principle design, and technical effects of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] A resolution-customizable miniature spectrometer based on a transversely dispersive metasurface is disclosed. The miniature spectrometer includes: a dispersive metasurface array structure 1, comprising several dispersive metasurface subarrays 101 arranged in an array and its all-dielectric substrate 102. A pixel-level polarization-insensitive metasurface structure is selected for preliminary spectral decoupling and directional focusing. The dispersive metasurface subarrays 101 include several dispersive metasurface units, which are nanopillars with four-fold symmetry. The nanopillars are periodically arranged, and the phase of the transmitted light is dynamically adjusted according to the incident light frequency ω, so that the focal position (x', y') of the transmitted light on the focal plane changes linearly with ω, thereby achieving customizable resolution.

[0033] The dispersive metasurface array structure 1 includes an all-dielectric substrate 102 and a dispersive metasurface subarray 101 arrayed on the all-dielectric substrate. Each dispersive metasurface subarray has the same spectral dispersion capability, and the focal position of the spectral convergence of different dispersive metasurface subarrays moves uniformly.

[0034] In each dispersive metasurface subarray, the spatial distribution of the required phase for the dispersive metasurface unit is as follows:

[0035] φ(x,y,ω)= +C(ω),

[0036] Where ω is the incident light frequency, F is the target focal length, c is the speed of light, (x,y) are the spatial coordinates on the metasurface, (x',y') is the spatial position of the transmitted light with frequency ω at the focal plane, θ represents the angle between the projection of the incident light onto the xz plane and the z-axis, γ represents the angle between the projection of the incident light onto the yz plane and the z-axis, and C(ω) is a function that depends only on frequency.

[0037] The spatial position (x', y') of the focal point of the transmitted light on the focal plane is determined by the frequency of the transmitted light, where x' = m1c / ω + n1 and y' = m2c / ω + n2. m1, m2 and n1, n2 are constants independent of wavelength. By changing the values ​​of m1, m2 and n1, n2, the focal position of each wavelength in the working band can be freely designed.

[0038] Dispersive metasurface subarrays are formed by micro- and nano-scale nanopillar arrays through micro- and nano-fabrication. Each nanopillar in the nanopillar array adopts an isotropic structure. Only the geometry of the nanopillars is changed, without rotating the nanopillars, that is, the transmission phase is changed while keeping the geometric phase the same, so as to produce the same phase modulation effect for different polarizations.

[0039] The focal plane pixel array 2, which is pixel-level registered with the dispersive metasurface subarray, has different pixels 202 that respond to incident light of different wavelengths. By performing simple spectral reconstruction on the response data, the spectral information of the incident light can be restored.

[0040] To address the challenge of balancing high spectral resolution and high energy efficiency in a single snapshot, this invention provides a miniature spectrometer based on a transversely dispersive metasurface.

[0041] The miniature spectrometer based on transversely dispersive metasurfaces consists of an array of dispersive metasurfaces with customizable focal points. The metasurfaces are composed of periodically arranged silicon nanopillars with high transmittance and low absorption loss in the mid-infrared band. To ensure the metasurfaces disperse light of any polarization state, the silicon nanopillars must satisfy four-fold symmetry. This structure ensures that the phase modulation of incident light by the superatoms does not change with the polarization state of the incident light. To maintain the modulation effect of the nanopillars on all polarization states, transmission phase modulation is required. Therefore, only the geometry of the nanopillars is changed, without rotating them, i.e., the transmission phase is changed while maintaining the same geometric phase. The phase responses of superatoms with different geometries and sizes to incident light of different wavelengths are calculated using the finite-difference time-domain method, constructing a superatomic phase library.

[0042] For each dispersive metasurface subarray with diameter D, light with frequency λ has an arbitrary polarization state, where λ is in the working wavelength range (λ... min , λ max Within the metasurface, incident light is focused at a fixed angle θ. Due to the different phase modulation results of the metasurface for incident light of different wavelengths, the outgoing light after passing through the metasurface is focused at the focal plane (m1λ+n1, m2λ+n2) with focal length F, where m1, m2 and n1, n2 are constants independent of wavelength. The focal distance between the two limiting wavelengths is Δr. 2 =Δx 2 +Δy 2 Δx=m1(λ max -λ min ), Δy=m2(λ max -λ min Finally, the detector receives the light signal from the focal plane.

[0043] According to the generalized Snell's law, the phase distribution of the dispersive metasurface units in a dispersive metasurface subarray must satisfy the following relationship:

[0044] φ(x,y,ω)= +C(ω)

[0045] Where ω is the incident light frequency, F is the target focal length, c is the speed of light, (x, y) are the spatial coordinates on the metasurface, (x', y') is the spatial position of the focal point of the transmitted light with frequency ω on the focal plane, θ represents the angle between the projection of the incident light onto the xz plane and the z-axis, and γ represents the angle between the projection of the incident light onto the yz plane and the z-axis. x' = m1c / ω + n1, y' = m2c / ω + n2, where m1, m2 and n1, n2 are constants independent of wavelength. By changing the values ​​of m1, m2 and n1, n2, the focal position of each wavelength within the working band can be freely designed. C(ω) is a function dependent only on frequency, and its partial derivative with respect to ω... = .

[0046] Calculations can yield the following results. =0,

[0047] Perform a Taylor expansion on the phase distribution φ(x,y,ω):

[0048] φ(x,y,ω)=φ(x,y,ω0)+ | ω0 (ω-ω0)+ | ω0 (ω-ω0) 2 +O(ω 3 )

[0049] Where ω min <ω0<ω max If the metasurface satisfies φ(x,y,ω0) for incident light of a certain frequency ω0, | ω0 and | ω0 Therefore, the metasurface satisfies the phase distribution relationship for incident light of any frequency within the target frequency range. Using a particle swarm optimization algorithm, superatoms matching the desired target phase are selected from the superatomic phase library, thus constructing a transversely dispersive metasurface.

[0050] By keeping m1 and m2 the same and uniformly changing the values ​​of n1 and n2, a series of dispersive metasurface subarrays with the same dispersion but uniformly shifted focal positions can be obtained. By constructing these subarrays into a dispersive metasurface array, different intensity distributions of the same spectral information can be detected at the focal plane, and high spectral resolution can be achieved through simple calculations.

[0051] The minimum spectral resolution achievable by a miniature spectrometer is determined by the dispersion distance of the dispersive metasurface, the detector pixel size, and the types of dispersive metasurface subarrays designed within the dispersive metasurface array. The smaller the detector pixel size, the larger the metasurface dispersion distance, and the more types of dispersive metasurfaces with different focal points in the metasurface array, the greater the spectral resolution that can be obtained.

[0052] Example 1

[0053] This invention discloses a micro-spectrometer with customizable resolution based on a transversely dispersive metasurface. The working principle and implementation effects of the micro-spectrometer will be introduced from two parts: dispersive metasurface manipulation and focal plane array spectral detection.

[0054] like Figures 1-2 As shown, the detected optical signal is incident on metasurface structure 1. Here, we take a target operating wavelength of 3-5µm, a metasurface diameter of 60µm, and a focal length F of 100µm as an example for design. The light has an arbitrary polarization state with wavelength λ, where λ is in the operating band (λ... min , λ max Within the metasurface, incident light at a fixed angle θ is focused at the focal plane (m1λ+n1, m2λ+n2) because the metasurface modulates the incident light of different wavelengths differently.

[0055] A focal plane pixel array that is pixel-level registered with the dispersive metasurface subarray allows different pixels to respond to incident light of different wavelengths. By performing simple spectral reconstruction on the response data, the spectral information of the incident light can be restored.

[0056] like Figure 3 As shown, the cross-sectional views of the three four-fold symmetric nanopillars used in this invention exhibit the same modulation effect on all polarization states. By changing the geometry of the nanopillars, the transmission phase is altered, and the geometric phase remains consistent without rotating the nanopillars. The phase response of superatoms with different geometries and sizes to incident light of different wavelengths is calculated using the finite-difference time-domain method, thus constructing a superatomic phase library.

[0057] like Figure 4 As shown, the wavelength decoupling effect of this invention is demonstrated. The x-coordinate positions of the focal points of 21 incident light wavelengths were calculated at equal wavelength intervals. The incident light with a wavelength of 3µm was focused at the focal plane spatial position (20µm, 0), the incident light with a wavelength of 5µm was focused at (-20µm, 0), and the focal points of the other incident light wavelengths were linearly distributed between (20µm, 0) and (-20µm, 0). The average absolute error between the focal positions of different wavelength incident light and their theoretical positions is less than 2%.

[0058] like Figure 5As shown, simulation results of the optical field focusing performance of this invention are demonstrated. Focusing efficiency is defined as the ratio of transmitted power within three FWHMs around the actual focal point to the power of light incident on the metasurface. In the operating wavelength range of 3-5µm, the average focusing efficiency exceeds 50%. At a wavelength of 4.4µm, the dispersive metasurface exhibits the highest focusing efficiency, at 62.443%.

[0059] This invention provides a micro-spectrometer with customizable resolution based on a lateral dispersive metasurface, comprising a dispersive metasurface array and a focal plane array. Different dispersive metasurface subarrays are customized with different focal center positions. The dispersive metasurface employs a pixel-level polarization-insensitive structure, achieving efficient spectral decoupling and directional focusing through precise control of the incident light phase. The focal plane array is precisely registered with the dispersive metasurface subarray, with different pixels responding to specific wavelengths. Simple spectral reconstruction of the response data restores the incident light spectral information. This invention employs a splitting mode to improve energy utilization and reduce light loss; pixel-level precise focusing is achieved through a metaatomic structure array, effectively suppressing crosstalk and improving detection accuracy; and lateral dispersion control eliminates the need for mechanical scanning, enabling true snapshot-style spectral imaging. It features a compact structure, customizable resolution, and fast response, providing an efficient and reliable miniaturized solution for spectral detection.

[0060] The above specific embodiments are used to explain and illustrate the present invention, and are only preferred embodiments of the present invention, not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A micro-spectrometer with customizable resolution based on a transversely dispersive metasurface, characterized in that: Including dispersive metasurface array structures and focal plane pixel arrays, The dispersive metasurface array structure includes several arrayed dispersive metasurface subarrays and its all-dielectric substrate for preliminary spectral decoupling and directional focusing. Each dispersive metasurface subarray comprises several dispersive metasurface units, which are nanopillars with four-fold symmetry. These nanopillars are periodically arranged, and the phase of the transmitted light is dynamically adjusted according to the incident light frequency ω, so that the focal position (x', y') of the transmitted light on the focal plane exhibits a linear mapping relationship with ω, thereby achieving customizable resolution. The spatial distribution of the phase of the dispersive metasurface units in each dispersive metasurface subarray is as follows: φ(x,y,ω)= +C(ω), Where ω is the incident light frequency, F is the target focal length, c is the speed of light, (x,y) are the spatial coordinates on the metasurface, (x',y') are the spatial positions of the transmitted light with frequency ω at the focal point on the focal plane, θ represents the angle between the projection of the incident light onto the xz plane and the z-axis, γ represents the angle between the projection of the incident light onto the yz plane and the z-axis, and C(ω) is a function that depends only on frequency. C(ω) is a function that depends only on frequency, and its partial derivative with respect to ω is... = , Calculated =0; The spatial position (x', y') of the transmitted light at the focal point of the focal plane is determined by the frequency of the transmitted light, where x' = m1c / ω + n1, y' = m2c / ω + n2, and m1, m2 and n1, n2 are constants independent of wavelength. By changing the values ​​of m1, m2 and n1, n2, the focal position of each wavelength in the working band can be freely designed. Keeping m1 = m2, and uniformly changing the values ​​of n1 and n2, a series of dispersive metasurface subarrays with the same dispersion but uniformly shifted focal positions are obtained. By constructing them into a dispersive metasurface array structure, different intensity distributions of the same spectral information can be detected at the focal plane. The spectral resolution can be further customized through simple calculations. Dispersive metasurface subarrays have the same spectral dispersion capability, and the focal point of spectral convergence of different dispersive metasurface subarrays shifts uniformly; The focal plane pixel array comprises a multi-dimensional planar array of several pixels, which is pixel-level registered with the dispersive metasurface subarray to record the spatial intensity distribution of light at different frequencies.

2. The micro-spectrometer with customizable resolution based on a transversely dispersive metasurface as described in claim 1, characterized in that: The dispersive metasurface array structure includes an all-dielectric substrate and a dispersive metasurface subarray distributed on the all-dielectric substrate.

3. The resolution-customizable micro-spectrometer based on a transversely dispersive metasurface as described in claim 1, characterized in that: For each dispersive metasurface subarray with diameter D, light with frequency λ has an arbitrary polarization state, where λ is in the working wavelength range (λ... min , λ max Within the array, light is incident at a fixed angle θ. Due to the different phase modulation results of the dispersive metasurface unit for incident light of different wavelengths, the outgoing light after passing through the dispersive metasurface unit is focused at the focal plane (m1λ+n1, m2λ+n2) with a focal length of F, where m1, m2 and n1, n2 are constants independent of wavelength. The focal distance between the two limiting wavelengths is Δr. 2 =Δx 2 +Δy 2 Δx=m1(λ max -λ min ), Δy=m2(λ max -λ min Finally, the detector receives the light signal from the focal plane.

4. The resolution-customizable micro-spectrometer based on a transversely dispersive metasurface as described in claim 1, characterized in that: Dispersive metasurface subarrays are formed by micro- and nano-scale nanopillar arrays through micro- and nano-fabrication. Each nanopillar in the nanopillar array adopts an isotropic structure. By changing only the geometry of the nanopillars without changing their spatial orientation, the transmission phase can be controlled.

5. The resolution-customizable micro-spectrometer based on a transversely dispersive metasurface as described in claim 1, characterized in that: The nanopillar material is selected from silicon, silicon nitride, or titanium dioxide.

6. The resolution-customizable micro-spectrometer based on a transversely dispersive metasurface as described in claim 1, characterized in that: The nanopillar has a square cross-section, a height h = 4.5 micrometers, a base period p = 1.65 micrometers, an outer side length of 1.0-1.4 micrometers, and an inner ring side length of 0.4-0.8 micrometers.

7. The resolution-customizable micro-spectrometer based on a transversely dispersive metasurface as described in claim 4, characterized in that: The cross-section of the nanopillars is shaped like a star.

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