Polarization independent electron-beam written 2-D longwave infrared guided-mode resonant filters

Abstract

We fabricated guided mode resonance filters (GMRFs) with two-dimensional (2-D) gratings operating in the 8 to 12 µm long-wave infrared (LWIR) region by depositing amorphous germanium (Ge) film to form a zero-contrast (ZC) waveguide-grating (WGG) on polished zinc selenide (ZnSe) substrates with and without antireflection coating (ARC). We employed high-spatial resolution e-beam lithography and reactive-ion etching (RIE) nanofabrication techniques. We characterized the fabricated filters for their polarization independent spectral performance using a tunable quantum cascade laser (QCL) system and a modified Fourier transform infrared (FTIR) spectrometer. Here, we will present both theoretical and experimental results and their comparison.