Spectroscopy Using a Guided-Mode Resonance InGaAs Photodetector Array

Snapshot spectroscopy has long been a goal for portable sensory imaging, but its realization has been limited by the lack of suitable spectral photodetectors. Here, we propose near-infrared spectroscopy based on an InGaAs photodetector array, utilizing guided-mode resonance and a reconstruction algorithm. The device is fabricated by integrating a thin InGaAs membrane photodetector on a precisely engineered silicon grating structure. All pixels of the photodetector array feature different grating structures, resulting in unique spectral responsivities. The guided-mode resonance induced by the silicon grating produces distinct absorption peaks in each pixel, significantly enhancing reconstruction efficiency compared to conventional reconstructive spectrometers based on broadband pixel arrays. The feasibility of single-snapshot spectroscopy was validated through transmittance measurements of ethanol, water, polycarbonate, and polyvinyl chloride. The spectroscopy with a guided-mode resonance InGaAs photodetector array enables on-chip integration with good reproducibility using conventional patterning and etching processes. This approach addresses the limitations of conventional bulky spectrometers and offers a promising platform for a wide range of sensing and imaging applications.