Wide-angle photon collection in deep-ultraviolet photodetectors via metalens integration

The authors demonstrate a compact and monolithically integrated strategy to enhance wide-angle light collection in deep-ultraviolet photodetectors operating at 265 nm by incorporating an Si3N4 metalens directly onto the sapphire optical window. The design addresses angular limitations of conventional packaging and achieves a 93× enhancement in photocurrent response at ±60° incidence. A single-angle phase profile is employed to simplify metalens fabrication while maintaining effective focusing over a 160° angular range. Finite-difference time-domain simulations confirm the experimental trends in angle-resolved power collection. The approach eliminates bulky optical components and offers a scalable path toward angularly adaptive and high-sensitivity UV photodetectors. Potential applications include fire detection, power grid monitoring, and secure UV communications.