Mercurous Bromide (Hg2Br2) Acousto-Optic Tunable Filters (AOTFs) for the Long Wavelength Infrared (LWIR) Region

This paper describes the development of acousto-optic tunable filter (AOTF) devices that are fabricated using in-house grown, high-quality single crystals of mercurous bromide (Hg2Br2). The Hg2Br2 crystals were grown using physical vapor transport (PVT). The quality of the Hg2Br2 single crystals are determined using high-resolution x-ray diffraction (HRXRD). The full width at half maximum (FWHM) of the (220) reflection was found to be 0.029 degrees, which is a significant improvement in the growth of Hg2Br2 bulk single crystals. The diffraction efficiencies of the fabricated AOTF device in the long wavelength infrared (LWIR) found to be 26% which is the highest reported. The device was tested for point detection and for imaging capabilities in the LWIR range. The study shows promising results using Hg2Br2 in LWIR AOTF-based technologies.