Polarisation-independent modulation of laser radiation by the acoustooptic interaction

A new type of polarisation-independent modulation of laser radiation with the aid of the acoustooptic interaction is considered. This modulation is based on the use of the properties of reflecting surfaces and of the acoustooptic properties of gyrotropic media. It is shown that polarisation-independent modulation of monochromatic radiation can always be realised over a wide range of acoustic wave frequencies. Three types of polarisation-independent modulation of two-frequency Ar laser radiation with the wavelengths 0.488 and 0.5145 μm are described. Experimental results are given for modulation in which the properties of a TeO₂ single crystal are used in a geometry ensuring the maximum diffraction efficiency. Polarisation-independent diffraction of the two-frequency Ar laser radiation by an acoustic wave of 58 MHz frequency is reported.