Acoustic mode analysis of multilayered structures for the design of acousto-optic devices

The acousto-optic transducer (AOT) is a fundamental component of a number of guided-wave devices and circuits suitable to the signal processing and optical computing. Most of such devices has been fabricated by using the LiNb03 technology, but some effort has been also spent on components based on lll/V semiconductor technology, i.e. GaAs and related compounds. However, because of the weak piezoelectric effect in these materials, it needs to analyze complex multilayer structures, including an additional ZnO superstrate, which shows an acoustic mode dispersion, due to the dependence of the surface acoustic wave (SAW) propagation speed on the acous.ic frequency applied to the transducer . In this paper a generalized model of the SAW propagation into multilayered structures has been applied to some typical acoustic waveguides, a simple semi-infinite layer of AlxGa-1 _xAs, as a function of the Al title x, a ZnO/AIGaAs structure, and a more complex ZnO/Alx1Ga-|_xiAs/Alx2Gai_X2As/GaAs structure, as a function of the intermediate layer thicknesses, frequency and Al titles x1 and x2.