Spectral properties of the acoustooptic guided-to-leaky wave conversion in an anisotropic waveguide

An experimental investigation was made of the spatial spectrum of waves emitted by an anisotropic optical LiNbO₃:Ti waveguide when a guided mode was converted into a leaky wave by interaction with a surface acoustic wave (SAW). The spectrum of the emitted field was modified greatly by the propagation of the diffracted radiation along a part of the anisotropic waveguide which was free of the SAW. The efficiency of the interaction with the SAW increased by two orders of magnitude for the radiation modes characterized by the maximum coupling coefficient.