Realization of high-contrast gratings operating at 10 μm

We present a new material pairing that can be used to realize high-contrast gratings at wavelengths of 10 mu m and greater. Using only optical lithography, the material pair solves the absorption issue limiting the popular Si/SiO2 pairing from operation above 6 mu m. We describe the obstacles that exist with the currently used grating materials for this wavelength range and outline why our chosen materials overcome this obstacle. We numerically demonstrate that gratings utilizing these materials are capable of wide-band high reflectivity. We experimentally show that the spectral response of gratings that are fabricated using such a process show good agreement with theoretically predicted performance. (C) 2016 Optical Society of America