Infrared color focal plane detector integrated with superlens

Abstract

The application discloses an infrared color focal plane detector integrated with a super-structured lens, wherein an infrared super-structured lens with a wide-spectrum separation and focusing function is prepared on a substrate of a planar structure infrared focal plane detector; after wide-spectrum infrared light is transmitted through the infrared super-structured lens, the wide-spectrum infrared light is separated into different spectrum bands; and the infrared light of different spectrum bands is respectively focused to a first sub-pixel, a second sub-pixel and a third sub-pixel of a super-pixel in the substrate. The three sub-pixels independently output detection signals, and an infrared color image is obtained by using an image synthesis method. The detector has the advantages of a wide working spectrum band, small signal crosstalk, less energy loss and high integration, and the infrared color image is obtained by using the infrared super-structured lens and the planar structure infrared detection chip.

Description

TECHNICAL FIELD

[0001] The present application relates to infrared multicolor focal plane detection technology and optical control technology, in particular to super surface phased array design and preparation technology, infrared focal plane detector design and preparation technology. BACKGROUND

[0002] Infrared color imaging is to obtain three or more bands of infrared signals by using an infrared detector, and to obtain an infrared color image through signal interpolation and image fusion. Infrared color imaging has the advantages of strong identification ability, anti-interference, and anti-deception.

[0003] The original infrared color detector has a separate super surface array and infrared detector, as disclosed in the invention patent: an infrared color detector based on a super surface (application number: CN202010965538.1). In the disclosed structure, the refractive and reflective optical phenomena exist between the super surface array and the infrared detector after the spectral separation of the infrared light, which increases the signal crosstalk. In addition, the optical coupling and fixing of the separate components also have certain difficulties.

[0004] The original infrared color detector integrates the super surface phased array on the substrate of the infrared monochrome focal plane detector, as disclosed in the invention patent: an infrared color focal plane detector integrating a super surface phased array in situ (application number: CN202110265605.3). In the disclosed structure, the super pixel unit only uses the incident light energy in the area directly above the second sub-pixel, and the signals incident directly above the first sub-pixel and the third sub-pixel are blocked or eliminated by the signal elimination method, which reduces the signal utilization rate of the integrated detector and also loses the original signals of the wide spectrum infrared light, which restricts the image processing capability.

[0005] The original infrared color detector integrates the infrared waveband beam splitting array on the substrate of the planar structure infrared detector, as disclosed in the invention patent: a super pixel infrared detector with spectral separation and full-transparency composite (application number: CN202110930651.0). In the disclosed structure, the surface micro-nano structure region corresponding to the first sub-pixel, the second sub-pixel and the third sub-pixel has a periodic boundary condition, and the two sides of the surface micro-nano structure region corresponding to the fourth sub-pixel have a continuous boundary condition. The boundary conditions inside and outside the surface micro-nano structure region are inconsistent, which leads to signal crosstalk and leakage of the first sub-pixel and the third sub-pixel, and reduces the image signal-to-noise ratio. SUMMARY

[0006] The present application provides an infrared color focal plane detector integrating a super lens, which solves the problems of complex refraction and reflection of signals in the existing infrared color detector, difficulty in coupling the separate super surface array and the planar structure infrared detector, low light signal utilization rate, and inconsistent boundary conditions of the infrared waveband beam splitting array leading to signal crosstalk.

[0007] In order to achieve the above-mentioned purpose, the present application adopts the following scheme:

[0008] An infrared color focal plane detector integrated with a super-structured lens, comprising a periodic infrared super-structured lens and a planar structure infrared focal plane detector, characterized in that:

[0009] The periodic infrared super-structured lens is prepared on the substrate of the planar structure infrared focal plane detector through thinning, polishing, photolithography and etching processes; a single super-pixel of the planar structure infrared focal plane detector corresponds to one period of the periodic infrared super-structured lens; three adjacent pixels of the planar structure infrared focal plane detector form a super-pixel, which are respectively a first sub-pixel, a second sub-pixel and a third sub-pixel; after the wide-band infrared light is vertically and parallelly incident on the periodic infrared super-structured lens, the transmitted light is spectrally separated and converged, the shorter-wavelength infrared light is separated and converged to the first sub-pixel, the medium-wavelength infrared light is separated and converged to the second sub-pixel, and the longer-wavelength infrared light is separated and converged to the third sub-pixel; the signals of the first sub-pixel, the second sub-pixel and the third sub-pixel are outputted, and an infrared color image is obtained by using a false color synthesis method.

[0010] Further, the infrared color focal plane detector integrated with a super-structured lens is characterized in that:

[0011] The periodic infrared super-structured lens is composed of surface micro-nano structures; the arrangement of the surface micro-nano structures follows the phase distribution of a multi-band separation lens; the periodic infrared super-structured lens has the effects of separating and converging the shorter-wavelength infrared light, the medium-wavelength infrared light and the longer-wavelength infrared light, and has the same focal length; the converging focal point positions of the periodic infrared super-structured lens for the shorter-wavelength infrared light, the medium-wavelength infrared light and the longer-wavelength infrared light are adjustable; the first sub-pixel, the second sub-pixel and the third sub-pixel correspond to one period of the periodic infrared super-structured lens directly above.

[0012] Further, the infrared color focal plane detector integrated with a super-structured lens is characterized in that:

[0013] The planar structure infrared focal plane detector is a back-illuminated photoelectric detector, and each pixel is independent of each other; the thickness of the substrate of the planar structure infrared focal plane detector is consistent with the focal length of the periodic infrared super-structured lens.

[0014] The present application has the following beneficial effects:

[0015] This invention provides an infrared color focal plane detector with integrated metalenses, offering advantages such as miniaturization, high integration, low crosstalk, and high signal sensitivity. The periodic infrared metalens is in-situ integrated onto the substrate of the planar infrared focal plane detector, avoiding multiple refractions and reflections of the light beam. A wide spectrum of incident infrared light can be used for signal imaging without the need to remove or block specific signals, thus improving signal utilization. The periodic infrared metalens is entirely composed of surface micro / nano structures with uniform boundary conditions between structures, reducing signal crosstalk and improving the signal-to-noise ratio. Attached Figure Description

[0016] Figure 1 This is a cross-sectional schematic diagram of an infrared color focal plane detector structure with integrated metalens, where 1 is a periodic infrared metalens, 1-1 is a surface micro / nano structure, 2 is a planar infrared focal plane detector, 2-1 is the first sub-pixel, 2-2 is the second sub-pixel, 2-3 is the third sub-pixel, and 2-4 is the substrate.

[0017] Figure 2 This is a top view of a single period of the periodic infrared metalens 1, and 1-1 shows the surface micro / nano structure. Detailed Implementation

[0018] Numerous specific details are set forth in the following description to provide a full understanding of the invention. However, the invention can be practiced in many other ways than those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0019] Example 1:

[0020] like Figure 1 As shown in the diagram, the integrated metalens infrared color focal plane detector provided in this invention includes a periodic infrared metalens 1 and a planar infrared focal plane detector 2. The substrate 2-4 of the planar infrared focal plane detector 2 is thinned using grinding and polishing processes. Then, surface micro / nano structures 1-1 are fabricated on the substrate using electron beam lithography (EBL) and reactive coupled plasma etching (ICP). The planar infrared focal plane detector 2 is a back-illuminated photodetector, with each pixel being independent. Each period of the periodic infrared metalens 1 corresponds to a superpixel of the planar infrared focal plane detector 2. A superpixel contains three pixels: a first subpixel 2-1, a second subpixel 2-2, and a third subpixel 2-3. Surface micro / nano structures 1-1 are located directly above each of the first subpixel 2-1, the second subpixel 2-2, and the third subpixel 2-3. The thickness of the substrate 2-4 of the planar infrared focal plane detector 2 is consistent with the focal length of the periodic infrared metalens 1.

[0021] likeFigure 2 As shown, a top view of a single period of the periodic infrared meta-lens 1 provided in this embodiment of the invention includes surface micro / nano structures 1-1.

[0022] The wavelength range of the vertically parallel incident broadband infrared light is 3μm to 4μm. The planar infrared focal plane detector 2 is a back-illuminated silicon-based mercury cadmium telluride detector, and the substrate 2-4 is made of silicon. A substrate 2-4 with a thickness of 235μm was obtained using grinding and polishing processes. A periodic infrared metalens 1 with a focal length of 235μm was fabricated on the substrate 2-4 using electron beam lithography (EBL) and reactive coupled plasma etching (ICP). The top view of the periodic infrared metalens 1 is a square with a side length of 64μm, containing 1024 surface micro-nano structures 1-1. The surface micro-nano structures 1-1 are all cylinders with different radii, a center-to-center spacing of 2μm, and a height of 3μm. The cylinder radii vary from 50nm to 900nm. The arrangement of the cylinders of the surface micro-nano structures 1-1 follows the phase distribution of a multi-band lens. One period of the periodic infrared metalens 1 corresponds to the first sub-pixel 2-1, the second sub-pixel 2-2, and the third sub-pixel 2-3 of the planar infrared focal plane detector 2. The pixel pitch of the planar infrared focal plane detector 2 is 21 μm, and each pixel is output independently.

[0023] Broadband infrared light passing through the periodic infrared metalens 1 undergoes spectral separation and convergence. Infrared light with wavelengths of 3μm to 3.35μm is separated and converged to the first sub-pixel 2-1, infrared light with wavelengths of 3.35μm to 3.8μm is separated and converged to the second sub-pixel 2-2, and infrared light with wavelengths of 3.8μm to 4μm is separated and converged to the third sub-pixel 2-3. Based on the pixel spacing and geometry of the planar infrared focal plane detector 2, the arrangement of the surface micro / nano structures 1-1 is changed to control the focal point position. The signals of the three sub-pixel units are output independently. An infrared color image is obtained by processing the signals of the first sub-pixel 2-1, the second sub-pixel 2-2, and the third sub-pixel 2-3 using a false-color synthesis method.

Claims

1. An infrared color focal plane detector with integrated metalens, comprising a periodic infrared metalens (1) and a planar infrared focal plane detector (2), characterized in that: The periodic infrared metalens (1) is fabricated on the substrate (2-4) of the planar infrared focal plane detector (2) through thinning, polishing, photolithography, and etching processes; a single superpixel of the planar infrared focal plane detector (2) corresponds to one period of the periodic infrared metalens (1); three adjacent pixels of the planar infrared focal plane detector (2) form a superpixel, namely the first subpixel (2-1), the second subpixel (2-2), and the third subpixel (2-3); width When infrared light of the spectral band is incident perpendicularly and parallel to the periodic infrared metalens (1), the transmitted light undergoes spectral separation and convergence. The shorter wavelength infrared light is separated and converged to the first sub-pixel (2-1), the medium wavelength infrared light is separated and converged to the second sub-pixel (2-2), and the longer wavelength infrared light is separated and converged to the third sub-pixel (2-3). The signals of the first sub-pixel (2-1), the second sub-pixel (2-2), and the third sub-pixel (2-3) are output, and an infrared color image is obtained by using a false color synthesis method. The periodic infrared meta-lens (1) is composed of surface micro-nano structures (1-1); the arrangement of the surface micro-nano structures (1-1) follows the phase distribution of a multi-band separation lens; the periodic infrared meta-lens (1) has the function of separating and converging shorter wavelength infrared light, medium wavelength infrared light, and longer wavelength infrared light, and the focal length is the same; the focal point position of the periodic infrared meta-lens (1) for shorter wavelength infrared light, medium wavelength infrared light, and longer wavelength infrared light is adjustable; the first sub-pixel (2-1), the second sub-pixel (2-2), and the third sub-pixel (2-3) correspond to one cycle of the periodic infrared meta-lens (1) directly above them. The planar infrared focal plane detector (2) is a back-illuminated photodetector, and each pixel is independent of the others; the thickness of the substrate (2-4) of the planar infrared focal plane detector (2) is consistent with the focal length of the periodic infrared metalens (1).

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