High-performance acousto-optic materials - Hg2Cl2 and PbBr2

New results achieved with recently grown Hg2Cl2 and PbBr2 crystals are described. With an optimized crystal growth technique Hg2Cl2 crystals were grown that show a significantly reduced acoustic attenuation compared to prior crystals, from 13.4 to 8 dB/microsec-GHz-squared. These crystals allow the development of Hg2Cl2 Bragg cells with time-bandwidth product figures in the 5100 to 6900 range, frequency operation as high as that for TeO2, and resolution about 25 percent higher than TeO2 for similar crystal lengths. PbBr2 crystals were also grown that exhibit a large figure of merit (M2 = 550) with an attenuation coefficient of 12 dB/microsec-GHz-squared. This material may be the choice for infrared devices where large diffraction efficiencies are needed.