Quantum-well-detector concept for hyperspectral coregistered full-Stokes-vector detection

Abstract

By layering quantum well stacks separated by partially transmissive linear gratings, similar to a multi-color QWIP, one may be able to detect the full Stokes vector at a single pixel. Such a detector would greatly aid polarization-based automated algorithms to detect targets from earth-gazing platforms. We report results from a theoretical calculation of normally incident infrared light absorbed by quantum wells in an eight-layer quantum-well/grating structure. The structure, illuminated from the substrate, consists of four quantum-well stacks, of 50 quantum wells each, separated by contact layers and lamellar gratings. The gratings following the first three quantum well stacks are formed by perfectly conducting rectangular strips separated by a transparent dielectric that allows some light to be transmitted. The top grating, following the fourth quantum well stack, is completely reflective. Each of the four lamellar gratings is oriented at a different angle. Incident radiation is diffracted and reflected to different orders and at different angles at each of the four gratings. The model is based on a uniaxial-optics transfer-matrix technique. We calculate the energy absorbed by each of the layers. This in turn allows one to predict and compare which layers will respond for partially-and fully-polarized incident light of either linear or circular polarization.