From Event: SPIE OPTO, 2023
Multispectral imaging (MSI) provides scenes with multiple narrowband spectral channels. It plays an important role in disciplines such as remote sensing and medical diagnoses. Based on multispectral filter arrays (MSFA), fast and integrated multispectral imaging can be achieved. We demonstrate a wide range multispectral Fabry-Perot (FP) color filter array based on two-dimensional subwavelength gratings and selective suppression. A thin metal layer is added inside the cavity of a FP resonator to selectively suppress the odd-order resonant peaks. The metal layer provides a larger free spectral range and smaller full width at half maximum (FWHM) compared to the conventional FP resonator while maintaining the high transmission. It also reduces the infrared transmission off the reflection range of the distributed Bragg mirror of the FP resonator. With selective suppression, we can exploit the second-order resonant peak by suppressing the odd-order resonant peaks. The smaller reflection phase shift and FWHM of the second-order transmission peak enable a wide range MSFA covering a spectrum from red to NIR (630nm-960nm) with FWHM smaller than 30nm. To be able to tune the resonant peak, we pattern nano-rods with grating or mesh structures in the cavity layers. By manipulating the shape and the size of nano-rods, we can tune the transmission peaks without changing the physical thicknesses of the layers. This has the promise of a monolithic broadband multispectral color filter array and paves the way for one-shot multispectral imaging.
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Jiewei Xiang, Meiting Song, Yi Zhang, Jennifer Kruschwitz, and Jaime Cardenas, "Monolithic broadband multispectral color filter array," Proc. SPIE 12432, High Contrast Metastructures XII, 1243208 (Presented at SPIE OPTO: February 01, 2023; Published: 15 March 2023); https://doi.org/10.1117/12.2648538.