Polarization‐Independent Single‐Band Guided‐Mode Resonance InGaAs Photodetector Array for Snapshot Multispectral Sensing

ABSTRACT Multispectral sensing in the short‐wave infrared (SWIR) range is highly desirable for a wide range of applications, from industrial inspection to satellite remote sensing. Here, we report a single‐band guided‐mode resonance (GMR) InGaAs photodetector (PD) array that enables single‐snapshot multispectral sensing through direct readout from each pixel. The device consists of an InGaAs PD with an ultrathin absorption layer bonded onto a Si 2D grating. Although a 2D crossed‐grating provides polarization independence, it inherently supports many more optical modes than a 1D grating. To realize a single‐band response, we introduce design strategies that suppress higher‐order diffraction using a thin grating and eliminate undesired modes by positioning their diffraction angles near the critical angle. The device exhibited a single‐band spectral response over a broad wavelength range of 1100–1700 nm, peak responsivities of up to 0.451 A/W, off‐peak responsivities below 0.03 A/W, and complete polarization independence. Moreover, a multispectral pixel array can be fabricated using a single patterning step by varying the grating period. We verified the feasibility of snapshot multispectral sensing through area‐scan imaging measurements under various input conditions. These results, together with the fabrication simplicity, establish the proposed device as a promising platform for compact, real‐time SWIR multispectral sensors.