Modeling of guided-wave acousto-optic multifrequency interaction in Bragg regime

In this work the modeling of non collinear acoustooptic multifrequency interaction in wave- guiding structures is presented. The new model, which is based on the generalized coupled mode theory, allows us to evaluate the diffraction efficiency in Bragg regime when a multifrequency signal is applied to the interdigitated transducer deposited on the optical waveguide surface. The dependence of diffraction efficiency of the output orders on the intermodulation factors and on the transducer driving radiofrequencies has been investigated. The influence of fabrication parameters of Ti:LiNbO3 waveguides on the linear dynamic range of acoustooptic multifrequency modulators has been extensively studied under monomodal propagation condition. Our results assert that the best performance in terms of linear dynamic range (approximately equals 43 dB) can be obtained on Ti:LiNbO3 waveguides having weak refractive index change ((Delta) n < 0.001), small initial titanium thickness (< 100 angstroms) and medium enter radiofrequency (approximately equals 500 MHz).