Metamirror-based quantum well infrared photodetectors with non-uniform gratings

Abstract

Circular polarization detection plays a crucial role in various fields such as optical communication, image recognition, and sensing. Quantum well infrared photodetectors (QWIPs), as mature infrared detectors, can discern circularly polarized light when combined with chiral metamaterials and metasurfaces. In this paper, we propose a metamirror-based QWIP that enables circular polarization identification in the long-wavelength infrared range of 7.5–9.5µm. The metamirror comprises two components: a top layer of an inclined 45° gold nanoprism metasurface and a bottom layer of one-dimensional gold grating patterns. Although each component alone does not have a chiral structure, their combination can emulate the compound eye structure of some arthropods in nature, forming chiral metamaterials that enable a circular polarization extinction ratio (CPER) of over 20 in QWIP devices. By adjusting the spacing of the bottom grating, our device achieves control over the response wavelength. Transitioning the grating from a uniform distribution to a non-uniform distribution enhances both the absorption and quantum efficiency of the device. The top gold metasurface array and the bottom gold grating selectively excite microcavity modes and surface plasmon polariton (SPP) modes, respectively, resulting in a total absorption of 0.9 and a quantum efficiency of 960% in the active region of the quantum well. This device presents an approach for applying QWIPs in polarimetric imaging, medical diagnosis, quantum information processing, and other fields.