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

Nanophotonic filter array detector array-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 Si<inf>3</inf>N<inf>4</inf> two-dimensional-dimerised metasurface spectral filter that exhibits sharp, narrow transmission dips. By tuning the metasurface grating period, we create a filter bank that covers a broad spectral range from 422 nm to 774 nm 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 1.0 nm. Our results pave the way for compact, mass-producible, on-chip spectrometers with strong potential for widespread deployment.