Polynomial Approximation of SAW Reflection Characteristics for Fast Device Simulation Tools.

The paper deals with the derivation of simple polynomials characterising surface acoustic wave (SAW) reflection by metallic gratings with various widths and thicknesses. Such polynomial approximation makes it possible to estimate coupling of mode (COM) parameters in markedly reduced computational time. For very sophisticated SAW devices, this is of great use to develop high-speed simulation and design tools based on the COM method. In the present study, it is shown how simply and accurately the SAW reflection by aluminium gratings on 128°YX-LiNbO3 substrates or 36°YX-LiTaO3 substrates is characterised by polynomial approximation.