Hyperspectral imaging chip, device and system based on adjustable reconfigurable metasurface

Abstract

The application discloses a hyperspectral imaging chip, device and system based on an adjustable reconfigurable metasurface, and the chip comprises a metasurface unit array, a metasurface reconfiguration module, a metasurface adjustment module, a CMOS image sensor and a spectrum reconstruction and identification module, the metasurface unit array comprises a plurality of metasurface units arranged on a silicon layer; the metasurface reconfiguration module is used for adjusting the number of metasurface units included in the reconfigurable metasurface unit array; the metasurface adjustment module is used for connecting the silicon layer of the metasurface unit array through wires, and is used for changing the spectral response of the metasurface unit by adjusting the voltage of the wires; the CMOS image sensor is used for detecting light signals from the reconfigurable metasurface unit array after modulation; and the spectrum reconstruction and identification module is used for performing hyperspectral reconstruction and imaging according to the light signals detected by the CMOS image sensor. The application has adjustable spectral response, ultrahigh spectral resolution, real-time dynamic monitoring capability and self-adaptive imaging capability.

Description

Technical Field

[0001] This invention relates to hyperspectral imaging chips, and more particularly to a hyperspectral imaging chip, device, and system based on an adjustable and reconfigurable metasurface. Background Technology

[0002] Spectral imaging technology is a key means of acquiring spatial and spectral information. This technology analyzes the composition and state of matter by capturing the spectral information of each point in the field of view, thus holding significant application potential in numerous research fields, particularly in real-time monitoring of complex processes. However, current spectral imaging technologies suffer from two main limitations: first, most techniques can only continuously acquire data within a limited wavelength range, failing to comprehensively reflect wide-bandwidth spectral changes; second, traditional spectral imaging equipment relies on spatial or temporal scanning, which cannot meet the requirements for high temporal, spatial, and spectral resolution. This poses a significant challenge to the study of rapidly changing activities, especially in real-time spectral imaging.

[0003] In recent years, spectroscopic devices based on micro / nano filters have been widely used to improve integration and miniaturization, with significant progress made, particularly in the development of on-chip integrated spectroscopic devices. These devices mainly fall into two categories: resonant filters and broadband filters. Resonant filters, such as microring resonators, optical microcavities, and resonant metasurface structures, can separate light of different wavelengths for spectral analysis, exhibiting high spectral resolution. However, resonant filters struggle to achieve wide spectral range detection while maintaining high spectral resolution. Broadband filters, such as quantum dot arrays, photonic crystal plate arrays, metasurface unit arrays, disordered scattering structures, and bandgap-tunable nanowires, recover the incident spectrum by encoding the spectral information of the incident light at different detector positions and combining this with computational spectral reconstruction algorithms. This makes the development of miniature spectrometers possible.

[0004] Despite the extensive progress made in the field of integrated microspectroscopy, existing technologies still face the following problems: once the metasurface unit is fabricated, its refractive index and spectral response mode are fixed. If other spectral response modes are required, the metasurface unit needs to be fabricated again, making it impossible to adjust the spectral response mode. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a hyperspectral imaging chip, device, and system with adjustable spectral response based on an adjustable and reconfigurable metasurface.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A hyperspectral imaging chip based on an tunable and reconfigurable metasurface includes:

[0008] A metasurface unit array, used to modulate incident light, comprises several metasurface units with different spectral responses arranged in an array, each metasurface unit being disposed on a silicon layer;

[0009] The metasurface reconstruction module is used to adjust the number of metasurface units included in the reconfigurable metasurface unit array according to the requirements of the fidelity, spectral resolution and spatial resolution of the reconstructed spectrum.

[0010] The metasurface adjustment module is connected to the silicon layer of the metasurface unit array via wires. It is used to apply an electric field to the corresponding metasurface unit by adjusting the voltage of the wires, thereby changing the refractive index of the corresponding metasurface unit and thus changing the spectral response of the metasurface unit.

[0011] CMOS image sensor for detecting optical signals modulated from a reconfigurable metasurface unit array;

[0012] The spectral reconstruction and recognition module is used for hyperspectral reconstruction and imaging based on the light signals detected by the CMOS image sensor.

[0013] Furthermore, the metasurface reconstruction module is specifically used to adjust the number of metasurface units included in the reconfigurable metasurface unit array according to the following rules:

[0014] Obtain the number of metasurface unit references for the reconstructed spectrum at reference fidelity, reference spectral resolution, and reference spatial resolution;

[0015] If the required spectral resolution for reconstructing the spectrum is increased compared to the reference spectral resolution, the number of metasurface units is reduced based on the reference number of metasurface units. If the required spectral resolution for reconstructing the spectrum is decreased compared to the reference spectral resolution, the number of metasurface units is increased based on the reference number of metasurface units.

[0016] If the required spatial resolution for reconstructing the spectrum is increased compared to the reference spatial resolution, the number of metasurface units is increased based on the reference number of metasurface units; if the required spatial resolution for reconstructing the spectrum is decreased compared to the reference spatial resolution, the number of metasurface units is decreased based on the reference number of metasurface units.

[0017] If the required fidelity for reconstructed spectra is higher than the reference fidelity, the number of metasurface units is increased based on the reference number of metasurface units; if the required fidelity for reconstructed spectra is lower than the reference fidelity, the number of metasurface units is decreased based on the reference number of metasurface units.

[0018] Furthermore, the metasurface adjustment module is specifically used to adjust the refractive index of the metasurface unit according to the following rules:

[0019] Obtain the refractive index of the metasurface unit at a reference voltage;

[0020] If it is necessary to increase the refractive index of the metasurface unit, then increase the absolute value of the wire voltage in the range of -5.2V to 5.2V;

[0021] If it is necessary to reduce the refractive index of the metasurface unit, then reduce the absolute value of the wire voltage in the range of -5.2V to 5.2V.

[0022] An optical imaging device having the aforementioned chip installed.

[0023] An optical imaging system comprising the aforementioned optical imaging device.

[0024] Compared with the prior art, the beneficial effects of this invention are:

[0025] 1. This invention can adjust the refractive index of the metasurface unit by adjusting the wire voltage of the silicon layer, thereby changing the spectral response of the metasurface unit and achieving multiple spectral responses;

[0026] 2. This invention employs a reconfigurable metasurface design, which can reconfigure the metasurface unit array according to the image scene, achieving seamless switching between image and spectral information;

[0027] 3. This invention achieves an optimal balance between high temporal, spatial, and spectral resolution, achieving a center wavelength accuracy of 0.04 nm and a spectral resolution of 0.8 nm, which is superior to most existing on-chip spectrometers;

[0028] 4. The chip uses a standard CMOS-compatible manufacturing process, which is low-cost and easy to integrate, and can be seamlessly integrated with existing optical imaging systems. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a hyperspectral imaging chip based on an adjustable and reconfigurable metasurface provided by the present invention.

[0030] Figure 2 These are schematic diagrams of five metasurface unit arrays with C4 symmetry provided by the present invention;

[0031] Figure 3 This is a spectral data diagram of monochromatic light reconstruction achieved using the present invention;

[0032] Figure 4 This is a spectral data diagram of polychromatic light reconstruction achieved using the present invention. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0034] This invention provides a hyperspectral imaging chip based on an adjustable and reconfigurable metasurface. This chip achieves real-time imaging with high temporal, spatial, and spectral resolution by constructing multiple microspectrometers on a CMOS image sensor. Figure 1 As shown, the chip includes a metasurface unit array, a metasurface reconstruction module, a metasurface adjustment module, a CMOS image sensor, and a spectral reconstruction and recognition module.

[0035] A metasurface unit array comprises several metasurface units arranged in an array, each with different spectral responses. Each metasurface unit is disposed on a silicon layer, and each metasurface unit constitutes a microspectrometer. Each metasurface unit is modulated by specific micro / nano patterns to respond to light of different wavelengths and generate a spectral response signal. The metasurface unit array has a C4 symmetry structure, such as... Figure 2 As shown, this helps to improve the uniformity of the spectral response and the spectral resolution.

[0036] In this embodiment, the metasurface unit is fabricated on a 220nm thick silicon-on-insulator (SOI) wafer using electron beam lithography. First, a pattern is formed using electron beam lithography, then the pattern is transferred to the silicon layer using inductively coupled plasma (ICP) etching. Finally, the intermediate silicon oxide layer is removed using wet etching, forming a suspended metasurface structure. Using a PDMS (polydimethylsiloxane) transfer process, the metasurface structure is transferred to a CMOS image sensor, achieving seamless integration with the sensor.

[0037] The metasurface reconstruction module is used to adjust the number of metasurface units included in the reconstructable metasurface unit array according to the following rules, based on the fidelity, spectral resolution, and spatial resolution requirements of the reconstructed spectrum:

[0038] The number of metasurface unit references for the reconstructed spectrum at reference fidelity, reference spectral resolution, and reference spatial resolution can be obtained experimentally.

[0039] If the required spectral resolution for reconstructing the spectrum is increased compared to the reference spectral resolution, the number of metasurface units is reduced based on the reference number of metasurface units. If the required spectral resolution for reconstructing the spectrum is decreased compared to the reference spectral resolution, the number of metasurface units is increased based on the reference number of metasurface units.

[0040] If the required spatial resolution for reconstructing the spectrum is increased compared to the reference spatial resolution, the number of metasurface units is increased based on the reference number of metasurface units; if the required spatial resolution for reconstructing the spectrum is decreased compared to the reference spatial resolution, the number of metasurface units is decreased based on the reference number of metasurface units.

[0041] If the required fidelity for reconstructed spectra is higher than the reference fidelity, the number of metasurface units is increased based on the reference number of metasurface units; if the required fidelity for reconstructed spectra is lower than the reference fidelity, the number of metasurface units is decreased based on the reference number of metasurface units.

[0042] For example, when 25 metasurface units are selected, the fidelity of the reconstructed spectrum from the transmission spectrum is approximately 96.2%, and the spectral resolution is approximately 1.4 nm. When the number of metasurface units is increased to 220, the fidelity of the reconstructed spectrum can be improved to 99.2%, and the spectral resolution is approximately 0.8 nm. Depending on the required fidelity of the reconstructed spectrum, the number of metasurface units can be adjusted within the range of 25 to 200, achieving dynamic adjustment of the reconstructed spectral resolution. Different microspectroscopy units can share some metasurface units, enabling optimized capture of spectral information within a certain spatial range without significantly sacrificing spatial resolution. For scenarios rich in spatial and spectral information, the shape of the microspectroscopy unit can be a regular rectangle or an irregular shape dynamically adjusted according to the imaging scene. The algorithm identifies edges or high-frequency regions in the image, preventing the spectrometer from crossing significant boundaries of the image, thereby maximizing the accuracy of spectral reconstruction.

[0043] The metasurface adjustment module is connected to the silicon layer of the metasurface unit array via wires. Adjusting the voltage of these wires within the range of -5.2V to 5.2V applies an electric field to the corresponding metasurface unit, changing its refractive index and thus its spectral response. This change in refractive index utilizes the Kerr photoelectric effect of silicon. By altering the refractive index of silicon, the transmission spectrum of the metasurface unit in the 400nm to 1000nm wavelength range is changed, thereby altering the spectral response of the metasurface unit. This allows for the creation of an image-adaptive microspectrometer through dynamic multiplexing.

[0044] Specifically, the relationship between the change in refractive index of the metasurface unit and the applied electric field is as follows:

[0045]

[0046] In the formula, Δn represents the change in refractive index of the metasurface unit, e is the electron charge, n is the refractive index of single-crystal silicon for light with a vacuum wavelength of λ, and m *Let ω0 be the effective mass of the electron, ω0 be the resonant frequency of the resonant model, x be the average displacement of the silicon atom, and E be the applied electric field strength. Since E is proportional to the absolute value of the voltage, Δn is proportional to the square of the voltage. Therefore, the metasurface adjustment module adjusts the refractive index of the metasurface unit according to the following rules: First, obtain the refractive index of the metasurface unit at the reference voltage; if it is necessary to increase the refractive index of the metasurface unit, increase the absolute value of the wire voltage within the range of -5.2V to 5.2V; if it is necessary to decrease the refractive index of the metasurface unit, decrease the absolute value of the wire voltage within the range of -5.2V to 5.2V.

[0047] A CMOS image sensor is used to detect optical signals modulated from a reconfigurable metasurface unit array. The hyperspectral imaging chip of this invention is integrated into a space with an area not exceeding 0.5 cm². 2 The CMOS image sensor contains up to 10 adaptive microspectrometers, each of which can be dynamically reconstructed according to the spectral and spatial resolution requirements of the imaging.

[0048] The spectral reconstruction and recognition module is used for hyperspectral reconstruction and imaging based on the light signals detected by the CMOS image sensor (CIS). Each metasurface unit has a specific spectral transfer function under a defined silicon layer voltage. The CIS sensor records the spectral signals from each metasurface unit, and then spectral reconstruction is performed using a compressed sensing algorithm to obtain a complete spectral image. In this way, real-time high-spectral resolution imaging can be achieved without relying on traditional scanning methods.

[0049] The hyperspectral imaging chip in this embodiment modulates incident light through a metasurface unit array to capture spectral information over a wide wavelength range. Each metasurface unit is equivalent to a miniature spectrometer. By dynamically combining these metasurface units and adjusting the silicon layer voltage of the metasurface units, the chip can operate in a wavelength range of 400nm to 1000nm. The spectral reconstruction results are as follows: Figure 3 , 4 As shown, the spectral resolution is as high as 0.8 nm, and the center wavelength accuracy is 0.04 nm.

[0050] The chip provided in this invention can be applied to any optical imaging device to achieve optical imaging, such as a CMOS industrial camera. It can also be applied to any optical imaging system, such as a confocal microscope and a Raman spectrometer, expanding its applications in different scenarios. Furthermore, by combining this invention with image recognition technology, seamless switching between image and spectral information can be achieved, thus opening up broader application prospects in fields such as medical imaging, environmental monitoring, and military detection.

[0051] It should be understood that the embodiments and descriptions above are only the principles, main features and advantages of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope of the invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A hyperspectral imaging chip based on an adjustable and reconfigurable metasurface, characterized in that, include: A metasurface unit array is used to modulate incident light. It includes several metasurface units with different spectral responses arranged in an array. Each metasurface unit is disposed on a silicon layer. Each metasurface unit is modulated by setting a micro-nano pattern and can respond to light of different wavelengths to generate a spectral response signal. Each metasurface unit has a specific spectral transfer function under a certain silicon layer voltage. The metasurface reconstruction module is used to adjust the number of metasurface units included in the reconfigurable metasurface unit array according to the requirements of the fidelity, spectral resolution and spatial resolution of the reconstructed spectrum. The metasurface adjustment module is connected to the silicon layer of the metasurface unit array via wires. It is used to apply an electric field to the corresponding metasurface unit by adjusting the voltage of the wires, thereby changing the refractive index of the corresponding metasurface unit and thus changing the spectral response of the metasurface unit. CMOS image sensor for detecting optical signals modulated from a reconfigurable metasurface unit array; The spectral reconstruction and recognition module is used to perform hyperspectral reconstruction and imaging based on the light signals detected by the CMOS image sensor. Specifically, spectral reconstruction is performed through compressed sensing algorithm to obtain a complete spectral image. By dynamically combining metasurface units and adjusting the silicon layer voltage of the metasurface units, the hyperspectral imaging chip can operate in the wavelength range of 400 nm to 1000 nm.

2. The hyperspectral imaging chip based on an adjustable and reconfigurable metasurface according to claim 1, characterized in that, The metasurface reconstruction module is specifically used to adjust the number of metasurface units included in the reconfigurable metasurface unit array according to the following rules: Obtain the number of metasurface unit references for the reconstructed spectrum at reference fidelity, reference spectral resolution, and reference spatial resolution; If the required spectral resolution for reconstructing the spectrum is increased compared to the reference spectral resolution, the number of metasurface units is reduced based on the reference number of metasurface units. If the required spectral resolution for reconstructing the spectrum is decreased compared to the reference spectral resolution, the number of metasurface units is increased based on the reference number of metasurface units. If the required spatial resolution for reconstructing the spectrum is increased compared to the reference spatial resolution, the number of metasurface units is increased based on the reference number of metasurface units; if the required spatial resolution for reconstructing the spectrum is decreased compared to the reference spatial resolution, the number of metasurface units is decreased based on the reference number of metasurface units. If the required fidelity for reconstructing the spectrum is greater than the reference fidelity, then the number of metasurface units should be increased based on the reference number of metasurface units. If the required fidelity for reconstructing the spectrum is reduced compared to the reference fidelity, then the number of metasurface units should be reduced based on the reference number of metasurface units.

3. The hyperspectral imaging chip based on an adjustable and reconfigurable metasurface according to claim 2, characterized in that, The number of metasurface units is adjusted within the range of 25 to 200 metasurface units.

4. The hyperspectral imaging chip based on an adjustable and reconfigurable metasurface according to claim 1, characterized in that, The metasurface adjustment module is specifically used to adjust the refractive index of the metasurface unit according to the following rules: Obtain the refractive index of the metasurface unit at a reference voltage; If it is necessary to increase the refractive index of the metasurface unit, then increase the absolute value of the wire voltage in the range of -5.2V to 5.2V; If it is necessary to reduce the refractive index of the metasurface unit, then reduce the absolute value of the wire voltage in the range of -5.2V to 5.2V.

5. The hyperspectral imaging chip based on an adjustable and reconfigurable metasurface according to claim 1, characterized in that, The metasurface unit array adopts a C4 symmetric structure.

6. The hyperspectral imaging chip based on an adjustable and reconfigurable metasurface according to claim 1, characterized in that, The metasurface units are formed using micro-nano manufacturing processes.

7. The hyperspectral imaging chip based on an adjustable and reconfigurable metasurface according to claim 6, characterized in that, The micro / nano manufacturing processes include electron beam lithography, inductively coupled plasma etching, or wet etching.

8. The hyperspectral imaging chip based on an adjustable and reconfigurable metasurface according to claim 1, characterized in that: The spectral reconstruction and recognition module uses a compressed sensing algorithm to perform spectral reconstruction on the acquired optical signals.

9. An optical imaging device, characterized in that, The device is equipped with a chip according to any one of claims 1 to 8.

10. An optical imaging system, characterized in that, The system includes the optical imaging device as described in claim 9.

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