Infrared nBn detectors monolithically integrated with metasurface-based optical concentrators

We demonstrate InAsSb-based infrared photodetectors monolithically integrated with metasurface lenses (metalenses) that act as optical concentrators. The metalenses are fabricated on the backside of a gallium antimonide substrate, and the photodetectors are fabricated on the frontside of the same substrate. The metalenses enhance the detector responsivity up to 10-fold and detectors retain the same detectivity at temperatures up to 40 K higher. Detectors integrated with metalenses exhibit detectivities greater than D* = 10(10) cm root Hz / W at lambda = 3.75 mu m up to room temperature. Our metasurface-based optical concentrators are based on circular subwavelength nanoposts, which renders their performance polarization independent.