Theoretical and experimental studies of LiNbO₃ degenerate acoustic elastic convolver

The crystal orientation dependencies of the figure of merit (M value) of different types of LiNbO₃ degenerate acoustic elastic convolvers (TVC, THC, BWC) have been theoretically and experimentally investigated. First, for TVC, it is shown that the theoretical M values using the nonlinear constants measured by authors these days have been in good agreement with their measured values. Second, for THC, the new definition of the figure of merit (M value) and practically effective equivalent circuit are proposed and the existence of the crystal cut and the direction of propagation with high efficiency and large electromechanical coupling coefficient is shown. Finally, this paper presents the efficient bulk wave mode for LiNbO₃ BWC by defining and calculating the M value for BWC.