Vol. 10, Issue 2, pp. 107-114 (1980)

Abstract

One of the most suitable materials for thin layer light modulation in the visible range is lithium niobate. A plate of lithium niobate of Y cut, thinned down to the thickness of order of 30μm with one side deposited with a metal layer, creates an assymmetric waveguide. The light flux from a He-Ne laser introduced to the plate with the help of a prism of BiGe0_2o single crystal propagates in the direction of x-axis. The surface acoustic wave, propagating in the z-axis direction, is generated by two interdigital transducers positioned close to each other. This waveguide enabled a propagation of 70 modes but only four of them positioned in the central part of the spectrum transmit a significant light intensity. After switching-on the acoustic wave of frequency 60 MHz and 187 MHz a diffractions of Raman-Nath and Bragg types in all these four significant modes was observed.