Suppression of the leakage effect in 64°YX-LiNbO3 for thick aluminium electrodes

In this paper we discuss the consequences of heavy mass loading on the propagation of leaky-waves on 64°YX-cut LiNbO₃. It has been predicted that using heavy and thick electrodes it is possible to slow down the leaky SAW beyond the velocity of the surface-skimming slow shear bulk wave and thus to suppress the energy losses due to bulk-wave radiation. This effect is observed in the admittance of a long resonator for h/λ=9-10% thick electrodes. The decrease of the attenuation and a strong increase in the Q factor of the resonance peak can be seen. A numerical model, based on the periodic Green´s function and the finite element method is used to further quantify the effect. We estimate that for aluminium electrodes of thickness 12% or for gold electrodes of thickness about 3% both the resonance and the antiresonance will be shifted into the nonleaky frequency region