Polarization selective uncooled infrared sensor using an asymmetric two-dimensional plasmonic absorber

Abstract

A polarization-selective uncooled infrared (IR) sensor has been developed based on an asymmetric two-dimensional plasmonic absorber (2-D PLA). The 2-D PLA has a Au-based 2-D periodic dimple structure, where photons can be manipulated by spoof surface plasmon polaritons. Asymmetry was introduced into the 2-D PLA to realize a polarization selective function. Numerical investigations demonstrate that a 2-D PLA with ellipsoidal dimples (2-D PLA-E) gives rise to polarization-dependent absorption properties due to the asymmetric dimple shape. A microelectromechanical systems-based uncooled IR sensor was fabricated using a 2-D PLA-E through a complementary metal oxide semiconductor (CMOS) and micromachining techniques. The 2-D PLA-E was formed by a Au layer sputtered on a SiO2 layer with ellipsoidal holes. An Al layer was then introduced on the backside of the 2-D PLA-E to reflect scattered light and prevent absorption at the SiO2 substrate. Measurement of the responsivity dependence on the polarization shows that the responsivity is selectively enhanced depending on the polarization and the asymmetry of the ellipse. The results provide direct evidence that a polarization-selective uncooled IR sensor can be realized simply by introducing asymmetry to the surface structure of a 2-D PLA without any polarizer or optical resonant structures. In addition, a pixel array where each pixel has a different detection polarization could be developed for polarimetric imaging using standard CMOS and micromachining techniques.