Acousto-optic Spatial Light Modulator (SLM) Based on KYW Crystal

We designed a new configuration of acousto-optic spatial light modulator based on biaxial crystal KY(WO4)(2) (KYW). This material has proved to be a good candidate to fill the gap between paratellurite having high acousto-optic efficiency and quartz having low efficiency but high laser-induced damage threshold. The modulator uses isotropic diffraction by a slow quasi-shear bulk acoustic wave propagating in the autocollimation direction. This ensures good compromise between acousto-optic figure of merit, which is only 30% less than in z-cut longitudinal-wave paratellurite, and high laser-induced damage threshold. The prototype modulator has the spatial resolution of 250 with the central frequency of 100 MHz and the aperture of 20 mm. The designed spatial light modulator is aimed at high-power ultrashort laser pulse shaping applications in near and middle infrared.