Design of an all-dielectric metasurface spectral filter array for compact high-performance reconstructive spectrometry

Nanophotonic filter array detector array (FADA)-based microspectrometers have gained significant attention for their compact size, low weight, CMOS compatibility, low cost, and low power consumption, making them ideal for mobile and field deployable applications. We present a microspectrometer design featuring a Si3N4 2D-dimerized metasurface spectral filter that exhibits sharp, narrow transmission dips. By tuning the metasurface grating period (GP), we create a filter bank that covers a broad spectral range from 422nm to 774nm while maintaining a high transmission contrast (> 90%) across the band. Unlike traditional bandpass filters, we introduce a bandstop filtering strategy, enhancing sensitivity by transmitting all wavelengths except the resonance wavelength. This approach enables improved signal extraction. Coupled with a spectral reconstruction algorithm, our design achieves high spectral resolution and is capable of detecting unknown signals with ultra-narrow linewidths down to 1.0nm. Our results pave the way for compact, mass-producible, on-chip spectrometers with strong potential for widespread deployment.