Metasurface coupled dynamic filtering infrared tunable spectral encoder
By designing a metasurface-coupled dynamic filtering infrared tunable spectral encoder, and employing a cantilever beam structure and metasurface spectral splitting technology, the problem of insufficient detection capability of infrared detection chips in complex environments was solved, achieving efficient spectral tuning and energy utilization, and improving target recognition capability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI INSTITUTE OF TECHNICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2025-07-22
- Publication Date
- 2026-07-07
AI Technical Summary
Existing infrared detection chips cannot avoid interference bands in complex environments, resulting in insufficient active detection capabilities and failing to meet the requirements for clear target identification in camouflaged and concealed scenarios. Furthermore, traditional spectral encoders have low energy utilization and cannot achieve dynamic spectral tuning.
Design a metasurface-coupled dynamic filtering infrared tunable spectral encoder. Employ a cantilever beam dynamic filter and a metasurface beam splitting structure to achieve dynamic spectral encoding. Utilize the metasurface structure to improve energy utilization and achieve dynamic tuning of the spectral range.
It improves the imaging performance of infrared detection chips, achieves dynamic tuning of the spectral range and high energy utilization, and enhances the target recognition capability in complex environments.
Smart Images
Figure CN224471147U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of infrared spectral detection integrated chips, and in particular to a metasurface coupled dynamic filtering infrared tunable spectral encoder. Background Technology
[0002] Infrared detection technology boasts advantages such as long operating range, strong anti-interference capabilities, high cloud and fog penetration, and all-weather operation. Spectral integrated detection, as a branch of multi-dimensional detection and imaging technology, is a key research area. Traditional infrared detection chips suffer from limitations due to their single-intensity detection mode, failing to avoid interference bands in complex environments to achieve active detection capabilities and meet the demands for clear target identification in camouflage and concealment scenarios. The new generation of infrared spectral integrated detection chips fully utilizes the "fingerprint recognition" characteristics of the infrared spectrum. Employing spectral active tuning technology, it dynamically adds a spectral dimension (x,y,λ) to the current two-dimensional spatial imaging of targets (x,y), creating a three-dimensional data cube. This allows for the selection of low-noise spectral channels to improve the signal-to-background ratio and achieve clear imaging performance. A key technology lies in the dynamic encoding of the incident light's narrowband spectrum, providing an effective spectral encoding channel for backend reconstruction imaging.
[0003] Current spectral encoders primarily use aperture encoding. Traditional aperture encoding filtering methods employ filtering for encoding, resulting in low energy utilization. For an N-channel spectral encoder, its energy utilization efficiency is only 1 / N of the total energy utilization efficiency.
[0004] Existing spectral encoders employ static filtering, fixing the selection of spectral bands and failing to actively tune the spectral range. Furthermore, the static spectral encoding results in different filtering ranges and transmittances in different regions, sacrificing photon energy of the incident light and spatial resolution of the detector chip. For example, the patent document "High-throughput Coding Aperture Component Suitable for Hyperspectral Video Imaging" (patent number CN202211428192.7, Xi'an Institute of Applied Optics) exemplifies a typical aperture filtering encoding method. The United States has made strides in this area. For instance, NASA's 2023 patent application, "Methods and Apparatus For Multi-Spectral Imaging Pyrometer Utilizing Tunable Optics" (US2023 / 0336846 A1), proposes a dynamically tunable metasurface filter concept. This concept uses thermally driven materials to dynamically tune the transmission spectrum, attempting to replace traditional mechanically rotating filter wheels used in aerospace remote sensing payloads. Therefore, China needs to strengthen its patent layout in this area, continuously follow up on the US patent layout, and seize the initiative for subsequent application and promotion. Utility Model Content
[0005] The purpose of this invention is to provide a metasurface-coupled dynamic filtering infrared tunable spectral encoder. It designs a dynamic spectral encoding element (Tunable Metafilter) based on a metasurface beam-coupled cantilever beam resonant cavity, targeting the core optical components required for front-end spectral encoding. The proposed metasurface-coupled dynamic tunable encoder, on the one hand, proposes a cantilever beam-based tunable filtering structure to achieve dynamic filtering; on the other hand, it couples a metasurface structure onto the filter surface, utilizing the metasurface beam-splitting method to maximize the use of incident light energy, thereby achieving dynamic beam-splitting encoding of infrared incident light.
[0006] This invention provides a metasurface coupled dynamic filtering infrared tunable spectral encoder, characterized in that it comprises a fixed mirror, a moving mirror, and a support layer; the moving mirror and the fixed mirror are bonded together to form a suspended layer; the support layer is disposed between the moving mirror and the fixed mirror; the moving mirror has a folded cantilever structure and is electrically connected to an external circuit through the support layer; the fixed mirror is electrically connected to an external circuit.
[0007] Furthermore, the fixed mirror includes a first substrate layer, a first electrode layer, and a first filtering region; both the first electrode layer and the first filtering region are located on the front side of the first substrate layer; the first electrode layer is located on the periphery of the first filtering region; and the first electrode layer is electrically connected to the external circuit.
[0008] Furthermore, the fixed mirror also includes a beam-splitting metasurface array; the beam-splitting metasurface array is located on the back side of the first substrate layer, opposite to the first filtering region.
[0009] Furthermore, the beam-splitting metasurface array is composed of an array of multiple superpixels; each superpixel is composed of nanopillars arranged in an orderly manner on a substrate, and includes one or more subpixels that form a beam-splitting channel.
[0010] Furthermore, the size of the substrate of the nanopillar is equivalent to half the operating wavelength of the sub-pixel; the height of the nanopillar is equivalent to the operating wavelength of the sub-pixel.
[0011] Furthermore, the substrate is square or hexagonal; the cross-sectional shape of the nanopillar is symmetrical.
[0012] Furthermore, the cross-sectional shape of the nanopillars is preferably elliptical, circular, cross-shaped, or annular.
[0013] Furthermore, the moving mirror includes a second substrate layer, a cantilever beam, a cantilever beam electrode, and a second filtering region; the cantilever beam is formed on the second substrate layer; the cantilever beam electrode and the second filtering region are located on the front side of the second substrate layer; the cantilever beam electrode is located on the outer ring of the cantilever beam and is electrically connected to the external circuit; the second filtering region is located on the inner ring of the cantilever beam.
[0014] Furthermore, an antireflection film region is provided on the back side of the second substrate layer; the antireflection film region covers the area where the cantilever beam is located.
[0015] Furthermore, there are multiple cantilever beams arranged in a centrally symmetrical shape.
[0016] The metasurface-coupled dynamic filtering infrared tunable spectral encoder of this invention has the following significant features compared with the prior art:
[0017] 1. This invention realizes a dynamic filter structure based on a multiphysics simulation model. The structure features a circular arc-shaped cantilever beam. The cantilever beam has a circular arc shape, with one end connected to the substrate and the other extending to the bridge surface area. The circular arc structure makes the filter structure more compact and effectively reduces stress, making the suspended structure more stable and able to support filtering operation even in a vacuum and low-temperature environment. This not only effectively reduces surface stress, resulting in a more stable suspended microbridge structure, but also makes the filter structure more compact, allowing for a larger area of filtering optical channels.
[0018] 2. This invention enables dynamic tuning of the spectral range, achieving active tuning of the transmission spectrum within the 3-5 micrometer mid-wave infrared range. The dynamic tuning function is further integrated into the metasurface beam-splitting structure, achieving multi-level dynamic beam-splitting coding, which can compensate for the spectral broadening defects caused by the suspended structure in traditional FP large-area dynamic filters. Fine-bandwidth spectral effects are obtained by utilizing the localization effect of the light field in the metasurface structure.
[0019] 3. This invention employs a metasurface spectral dispersion method, integrating a subwavelength metasurface structure onto a dynamic filter structure to further achieve fine spectral dispersion and focusing. It can comprehensively utilize incident light, focusing and dispersing it again to ensure energy utilization efficiency, which is essentially limited only by the transmittance of the metasurface structure. Compared to traditional static encoders that use filtering effects for spectral encoding, this reduces light energy loss and provides ample assurance for energy collection and detection utilization by the downstream detector. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of a preferred embodiment of the dynamic filtering infrared tunable spectral encoder of the present invention;
[0021] Figure 2 This is a side view of a preferred embodiment of the dynamic filtering infrared tunable spectral encoder of the present invention;
[0022] Figure 3 This is a top view of a cantilever beam in a preferred embodiment of the dynamic filtering infrared tunable spectral encoder of the present invention.
[0023] Figure 4 This is a schematic diagram of the structure of the beam-splitting metasurface array in a preferred embodiment of the dynamic filtering infrared tunable spectral encoder of the present invention;
[0024] Figure 5 This is a schematic diagram of the operation of a superpixel in a spectroscopic metasurface array in a preferred embodiment of the dynamic filtering infrared tunable spectral encoder of the present invention.
[0025] In the diagram: 1-Fixed mirror, 2-Moving mirror, 3-Support layer;
[0026] 11-First substrate layer, 12-First electrode layer, 13-First filtering region, 14-Spectroscopic metasurface array; 141-Superpixel, 142-Subpixel;
[0027] 21-Second substrate layer, 22-Cantilever beam, 23-Cantilever beam electrode, 24-Second filter region, 25-Antireflection film region, 26-Circular bridge surface region. Detailed Implementation
[0028] The specific embodiments of this utility model will be described below with reference to the accompanying drawings.
[0029] Please see Figure 1 , Figure 2 and Figure 3 This invention discloses a metasurface-coupled dynamically filtered infrared tunable spectral encoder. As shown in the figure, a preferred embodiment features a multi-level dynamic spectral encoding function for the 3-5 micrometer mid-wave infrared range. It consists of a fixed mirror 1, a moving mirror 2, and a support layer 3, employing a multi-level combined dynamic spectral encoding method. Both the fixed mirror 1 and the moving mirror 2 are independently fabricated on a silicon substrate. After fabrication, the fixed mirror 1 and the moving mirror 2 are bonded together and isolated by the support layer 3, thus forming a suspended layer between them. The support layer 3 also serves as an electrical conduction channel between the fixed mirror 1 and the moving mirror 2. In this embodiment, the support layer 3 is fabricated together with the fixed mirror 1, forming an indium pillar grown on the structure of the fixed mirror 1, and then bonded to the moving mirror 2. The height of the indium pillar is 2 micrometers. The moving mirror 2 has a folded cantilever structure. Under the action of an external electric field, electrostatic force is applied to the folded cantilever structure, causing it to bend. This results in a change in the height of the suspended layer between mirror 1 and moving mirror 2, thereby realizing the first-level dynamic tuning function, that is, the first-level dynamic beam splitting function of the incident light.
[0030] The fixed mirror 1 includes a first substrate layer 11, a first electrode layer 12, a first filtering region 13, and a beam-splitting metasurface array 14. The first substrate layer 11 is a silicon substrate. The first electrode layer 12 and the first filtering region 13 are fabricated on the front side of the first substrate layer 11. The first electrode layer 12 is a gold-based electrode layer composed of multiple gold electrode groups. The first filtering region 13 is located in the center, while the first electrode layer 12 is located around the first filtering region 13. The beam-splitting metasurface array 14 is disposed on the back side of the fixed mirror 1, i.e., fabricated on the back side of the first substrate layer 11. The beam-splitting metasurface array 14 performs a second-stage beam splitting function, further splitting and converging the incident light to ensure energy utilization. The beam-splitting metasurface array 14 is opposite to the first filtering region 13 located on the front side of the first substrate layer 11, and its size matches the size of the first filtering region 13. In this embodiment, the thickness of the first substrate layer 11 is 400 micrometers, and the thickness of the first electrode layer 12 is 150 nanometers. In another embodiment, the first substrate layer 11 has a thickness of 500 micrometers and the first electrode layer 12 has a thickness of 150 nanometers.
[0031] Correspondingly, the moving mirror 2 includes a second substrate layer 21, a cantilever beam 22, a cantilever beam electrode 23, and a second filtering region 24. The second substrate layer 21 is a silicon substrate. On the front side of the second substrate layer 21, the cantilever beam 22 is fabricated to form a folded cantilever structure.
[0032] Multiple cantilever beams 22 are formed by etching through the second substrate layer 21. In this embodiment, there are three arc-shaped cantilever beams 22, which are arranged in a circle around each other, forming a complete circle with the center of the circle as the center of symmetry. A circular bridge surface region 26 is formed in the area surrounded by these three cantilever beams 22. The circular bridge surface region 26 is supported by the three cantilever beams 22, forming a complete folded cantilever structure. Cantilever beam electrodes 23 are fabricated along the outer ring of the cantilever beams 22. A second filter region 24 is set in the central region of the cantilever beams 22, that is, below the circular bridge surface region 26. An antireflection film is fabricated on the back side of the moving mirror 2, forming an antireflection film region 25. The antireflection film region 25 is opposite to the region of the second filter region 24, and its area is larger than the region of the suspended layer, that is, it covers the second filter region 24 located on the front side of the second substrate layer 21. In this embodiment, the second substrate layer 21 has a thickness of 100 micrometers, the cantilever beam electrode 23 has a thickness of 150 nanometers, and the radius of the top circular bridge surface region 26 is 3.75 millimeters.
[0033] After the fixed mirror 1 and the moving mirror 2 are bonded, the first electrode layer 12 and the cantilever beam electrode 23 are opposite each other, and the first filtering region 13 and the second filtering region 24 are opposite each other. A suspended layer is formed in the gap between the first filtering region 13 and the second filtering region 24. Specifically, the first filtering region 13 of the fixed mirror 1 is located below the suspended layer, forming the bottom of the suspended layer. The second filtering region 24 of the moving mirror 2 is located above the suspended layer, forming the top of the suspended layer. Both the first electrode layer 12 and the cantilever beam electrode 23 are electrically connected to an external circuit, respectively connected to the positive and negative terminals. In this way, the external circuit can control the degree of deformation of the cantilever beam 22 by applying a bias voltage to the first electrode layer 12 and the cantilever beam electrode 23. The greater the degree of deformation of the cantilever beam 22, the smaller the distance between the first filtering region 13 and the second filtering region 24, and vice versa.
[0034] Please see Figure 4 and Figure 5 The function of the beam-splitting metasurface array 14 is to achieve second-order beam splitting. It is an array composed of multiple superpixels 141. Each superpixel 141 contains multiple beam-splitting channels. The original light rays incident on the superpixel 141 are filtered out by the beam-splitting channels to remove specific wavelengths. Different beam-splitting channels have different filtering characteristics, so after the original light rays pass through the superpixel 141, they are split into multiple sub-rays containing different wavelengths. The specific structure of the beam-splitting channel is the subpixel 142. Each superpixel 141 contains the same number of subpixels 142 as the beam-splitting channels. Each subpixel 142 can be regarded as a beam-splitting channel, which is composed of ordered nanopillars arranged on a substrate to form a beam-splitting structure. In the subpixel 142, the overall phase distribution is determined according to the beam-splitting components. The different sizes of the substrate and nanopillars determine the structural parameters of the subpixel 142. Specifically, the size of the nanopillar substrate is equivalent to half of the beam-splitting operating wavelength, while the height of the nanopillar is equivalent to the beam-splitting operating wavelength. Under the premise of meeting the above requirements, the shape of the nanopillar substrate can be selected in various ways, as long as it covers the entire plane, such as square or hexagonal. The cross-sectional shape of the nanopillar is preferably a symmetrical shape, such as rectangular, elliptical, circular, cross-shaped, and annular. In this embodiment, a superpixel 141 contains four sub-divisions, indicating that the incident light is divided into four parts. In different scenarios, the number of beam splitting can also be customized according to the application scenario. After the incident light passes through the superpixel 141, it is split into multiple beams. As shown in the figure, the spectral information of multiple components is distributed in a dynamically tunable broadband band and exhibits a multi-peak interlacing phenomenon, which has a certain orthogonal characteristic, ensuring that the light fields of each channel of the dynamic filter can be utilized with high energy and decomposed and encoded when they enter.
[0035] In this embodiment, the beam-splitting metasurface array 14 consists of N×N sub-pixels. When splitting four beams, the ideal state of the meta-pixel 141 structural unit is 2×2, which provides the highest spatial resolution. The nanopillars in each sub-pixel 142 have a square or hexagonal substrate. The cross-sectional shape of the nanopillars adopts a highly symmetric pattern, including but not limited to square, circular, cross-shaped, and annular shapes. In another embodiment, the nanopillar substrates in the beam-splitting metasurface array 14 are arranged in a square pattern. The cross-sectional shape of the nanopillars adopts a symmetry pattern of C4 or higher, including but not limited to elliptical, square, and circular shapes.
[0036] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of this utility model. All equivalent changes and modifications made within the scope of the claims of this utility model should be considered within the technical scope of this utility model.
Claims
1. A metasurface-coupled dynamic filtering infrared tunable spectral encoder, characterized in that, It includes a fixed mirror, a moving mirror, and a support layer; the moving mirror and the fixed mirror are bonded together to form a suspended layer; the support layer is disposed between the moving mirror and the fixed mirror; the moving mirror has a folding cantilever structure and is electrically connected to an external circuit through the support layer; the fixed mirror is electrically connected to an external circuit.
2. The dynamically filtered infrared tunable spectral encoder according to claim 1, characterized in that, The fixed mirror includes a first substrate layer, a first electrode layer, and a first filtering region; the first electrode layer and the first filtering region are both located on the front side of the first substrate layer; the first electrode layer is located on the periphery of the first filtering region. The first electrode layer is electrically connected to the external circuit.
3. The dynamically filtered infrared tunable spectral encoder according to claim 2, characterized in that, The fixed mirror further includes a beam-splitting metasurface array; the beam-splitting metasurface array is located on the back side of the first substrate layer, opposite to the first filtering region.
4. The dynamically filtered infrared tunable spectral encoder according to claim 3, characterized in that, The beam-splitting metasurface array is composed of an array of multiple superpixels; each superpixel is composed of nanopillars arranged in an orderly manner on a substrate, and includes one or more subpixels that form a beam-splitting channel.
5. The dynamically filtered infrared tunable spectral encoder according to claim 4, characterized in that, The size of the substrate of the nanopillar is equivalent to half the operating wavelength of the sub-pixel; the height of the nanopillar is equivalent to the operating wavelength of the sub-pixel.
6. The dynamically filtered infrared tunable spectral encoder according to claim 5, characterized in that, The substrate is square or hexagonal; the cross-sectional shape of the nanopillar is symmetrical.
7. The dynamically filtered infrared tunable spectral encoder according to claim 6, characterized in that, The cross-sectional shape of the nanopillars is preferably elliptical, circular, cross-shaped, or annular.
8. The dynamically filtered infrared tunable spectral encoder according to claim 1, characterized in that, The moving mirror includes a second substrate layer, a cantilever beam, a cantilever beam electrode, and a second filtering region; the cantilever beam is formed on the second substrate layer; the cantilever beam electrode and the second filtering region are located on the front side of the second substrate layer; the cantilever beam electrode is located on the outer ring of the cantilever beam and is electrically connected to the external circuit; the second filtering region is located on the inner ring of the cantilever beam.
9. The dynamically filtered infrared tunable spectral encoder according to claim 8, characterized in that, An antireflection film area is provided on the back side of the second substrate layer; the antireflection film area covers the area where the cantilever beam is located.
10. The dynamically filtered infrared tunable spectral encoder according to claim 8, characterized in that, There are multiple cantilever beams arranged in a centrally symmetrical shape.