Design and fabrication of Fabry–Perot filters for infrared hyperspectral imagers

Hyperspectral infrared imagers are of great interest in applications requiring remote identification of complex chemical agents. The combination of mercury cadmium telluride detectors and Fabry–Perot filters (FPFs) is highly desirable for hyperspectral detection over a broad wavelength range. The geometries of distributed Bragg reflector (DBR)-based tunable FPFs are modeled to achieve a desired spectral resolution and wavelength range. Additionally, acceptable fabrication tolerances are determined by modeling the spectral performance of the FPFs as a function of DBR surface roughness and membrane curvature. These fabrication nonidealities are then mitigated by developing an optimized DBR process flow yielding high-performance FPF cavities suitable for integration with hyperspectral imagers.