Nanofabricated Infrared Polarization and Color Filters for Cloud Thermodynamic Phase Determination

Polarization and wavelength filters for the shortwave infrared based on metal-coated subwavelength-period silicon gratings are designed and fabricated. The nanostructure-based approach enables the realization of the desired polarization and wavelength selectivity for each filter element while also facilitating the integration of these elements into an array with varying polarizer orientation and passband center wavelength. These filters are optimized for a polarimetric imaging application in atmospheric science, namely, the discrimination of cloud thermodynamic phase (ice/water composition). Preliminary results support the viability of this approach.