Ultrabroadband, High Color Purity Multispectral Color Filter Arrays

Multispectral imagers that capture spatiospectral information are of growing importance in various fields, particularly in remote sensing and metrology. To enable integrated snapshot multispectral imagers and eliminate the drawbacks of traditional systems, such as bulkiness and slow scanning mechanisms, miniature, broadband multispectral filter arrays with narrow line widths, high transmission, and Complementary Metal Oxide Semiconductor (CMOS) compatibility are essential. However, current miniature transmissive filter arrays, primarily based on diffractive nanostructures, suffer from limitations such as small working bandwidth, low transmission, poor color purity, and sensitivity to polarization and incident angles. To address these challenges, we present a high-order Fabry-Perot multispectral filter array (MSFA) with selective peak suppression, leveraging subwavelength nanostructures for filter tuning without changing the physical thickness and employing an ultrathin metal layer to exploit high-order resonances, significantly extending the working range and spectral resolution. High color purity across a broad range (400-1000 nm) is made possible through optical absorption from polysilicon and selective suppression from a platinum layer. The fabricated color filter arrays cover wavelengths from 622 to 960 nm, with full width at half-maximum (FWHM) ranging from 13 to 31 nm and average transmissions exceeding 60%. Our filters also show low sensitivity to oblique incident angles of up to 30(degrees) with minimal wavelength shifts. Furthermore, these filters can be downscaled to sizes compatible with modern CMOS imagers, reaching dimensions as small as 1 mu m. The introduction of a resonance combining design further extends the working range (455-960 nm), aligning with the capabilities of silicon photodetectors. Its adaptability across wavelength ranges and potential for tunable applications hold promise for transformative imaging and display technologies across a wide spectrum.