Compact meta-spectral image sensor for mobile applications

Abstract

We have demonstrated a compact and efficient metasurface-based spectral imager for use in the near-infrared range. The spectral imager was created by fabricating dielectric multilayer filters directly on top of the CMOS image sensor. The transmission wavelength for each spectral channel was selected by embedding a Si nanopost array of appropriate dimensions within the multilayers on the corresponding pixels, and this greatly simplified the fabrication process by avoiding the variation of the multilayer-film thicknesses. The meta-spectral imager shows high efficiency and excellent spectral resolution up to 2.0 nm in the near-infrared region. Using the spectral imager, we were able to measure the broad spectra of LED emission and obtain hyperspectral images from wavelength-mixed images. This approach provides ease of fabrication, miniaturization, low crosstalk, high spectral resolution, and high transmission. Our findings can potentially be used in integrating a compact spectral imager in smartphones for diverse applications.

Recent Advances and Prospects of Optical Metasurfaces

“…Another approach is to directly fabricate metasurfaces on CIS. Lee et al designed a metasurface-based bandpass filter array for spectral imaging . The bandpass filter array consists of nanopost arrays with diverse resonance wavelengths, and it was sandwiched between multiple dielectric layers.…”

“…Lee et al designed a metasurface-based bandpass filter array for spectral imaging. 181 The bandpass filter array consists of nanopost arrays with diverse resonance wavelengths, and it was sandwiched between multiple dielectric layers. To create a compact prototype, the bandpass filter array was fabricated on a bare CIS wafer using standard lithography.…”

Superconducting Single-Photon Spectrometer with 3D-Printed Photonic-Crystal Filters

“…Consequently, F (λ) can be reconstructed by solving eq , as shown in Figure e, and this process is known as decoding (see Supporting Information, S1). Compared to conventional dispersive and narrowband-filtered spectrometers, computational strategy − has advantages in terms of the number of detection channels. The numbers of detectors and wavelength channels are not required to be equal ( m ≠ n ).…”

Hybrid Fabry-Perot cavity for multispectral analysis: an experimental demonstration

“…On the other hand, dielectric subwavelength gratings made from silicon-based materials have lower intrinsic losses in the near-infrared range, say 𝜆 ≥ 700 nm, which makes them a preferred option for improving the spectral features of CMOS image sensor devices [6]. Several studies showed that combinations of both Fabry Perot cavity and a 2D or 3D subwavelength gratings, i.e., hybrid Fabry-Perot Cavity (h-FPC), are very promising solutions for feasibility and tunability [7][8][9]. For instance, an h-FPC that consists of two Bragg mirrors with periodic dielectric rods at the center of the cavity displays an enhanced angular tolerance compared to a planar FPC [10].…”