Tunable narrowband photodetection based on few-layer MoS ₂ : achieving high absorption across the visible and near-infrared

Narrowband photodetectors are essential for high-resolution imaging, optical communication and spectral monitoring. Few-layer MoS2 (FL-MoS2) possesses high carrier mobility and tunable band structure, yet suffers from weak optical absorption above 700 nm, restricting its practical photodetection performance. To tackle this limitation, we propose a resonant photodetector integrating FL-MoS2 with cross-shaped air channels. Finite-element simulations confirm that critical-coupling and guided-mode resonance (GMR) realize selective, efficient light absorption. By tuning device dimensions, the absorption peak is continuously adjustable from 710 to 810 nm, achieving a maximum absorption of 99.75 % and competitive detection capability. The optimized device delivers a responsivity of 0.34 A/W, a specific detectivity of 5.38 × 1010 Jones and an external quantum efficiency of 52.2 %. This work offers feasible design strategies and theoretical guidance for high-performance tunable FL-MoS2-based narrowband photodetectors.