Abstract
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.
Highlights
Optical spectrometers are used in many fields, and applications range from material analysis and astronomy to food chemistry and medical diagnostics
We have demonstrated a compact and efficient metasurface-based spectral imager for use in the nearinfrared range
The spectral imager was created by fabricating dielectric multilayer filters directly on top of the CMOS image sensor
Summary
Optical spectrometers are used in many fields, and applications range from material analysis and astronomy to food chemistry and medical diagnostics. Resonant structures for narrow bandpass filters used in spectrometers were investigated, but most studies are limited to varying the thicknesses of dielectric multilayers to form an optical cavity for different wavelengths and quality factors [19, 20]. This is cumbersome for mass production of devices because it would require an excessive number of dielectric deposition, etching, and photolithography steps, especially at pixel size levels [21]. We obtained hyperspectral images from wavelength-mixed images
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