Optical probing of surface acoustic wave generation under interdigital transducers

Abstract
High‐resolution optical spectroscopy was used to study the growth of continuously excited surface acoustic waves under 15‐ and 25‐finger‐pair aluminum interdigital transducers on y‐cut z‐propagating lithium niobate. The observed exponential growth of the surface wave with distance is in agreement with simple coupled‐mode theory. The coupling parameter leads to a direct evaluation of the effective electromechanical coupling constant K. For yz LiNbO3 a value of K2=0.030±0.003 was found.