Metasurface Quantum Well Photodetectors with Broadened Photoresponse Using a Patchwork of Cavities within a Subwavelength Period

The integration of quantum well infrared photodetectors with plasmon cavities has allowed for demonstration of sensitive photodetectors in the mid-infrared. These detectors typically use only a single type of plasmon cavity, but previous studies of metasurface absorbers has shown that combining multiple cavities in a single subwavelength period can generate complex photoresponses such as multi-band and broadband absorption. In this report, we use a simple square cavity design as a building block for demonstrating detectors with a broadened photoresponse. Device performance of simple square detectors is comparable to previous highdetectivity designs, and by using a patchwork of square cavities within a single subwavelength period, we can subsequently broaden photoresponse by 1.5 times. Absorption in these patchwork cavity detectors shows good agreement with previous reports for metasurface absorbers, and suggests that this design and fabrication process could serve as a roadmap for integrating detectors and metasurface cavities with more complex photoresponses.