VO2 wire grid polarizers for MWIR applications

Abstract

Phase change materials (PCMs) have received a lot of attention recently due to their ability to reversibly switch between phases producing large changes in their optical and electrical properties.VO2 is unique compared to other chalcogenide-based PCMs due to its volatile switching behavior, allowing it to automatically reset when the thermal stimulus is removed. It is able to switch between a metallic rutile phase and a monoclinic semiconducting phase, making it an ideal candidate for polarization control. In this paper, we demonstrate a VO2 wire grid polarizer with an extinction ratio as high as 6 dB in the midwave infrared (MWIR) spectrum that can be thermally turned on and off. We used a novel, to the best of our knowledge, approach to fabricate these devices, using conventional photolithography and lift-off processes on metallic vanadium followed by thermal oxidation in a furnace. This is a significantly simpler and a scalable procedure compared to current processes of patterning and etching VO2.