A method of search for leaky waves based on exceptional wave theory

A method of search for leaky waves in crystals is based on the calculation of permitted orientations for exceptional bulk waves, which satisfy the stress-free boundary conditions for surface waves. This method is applied to quartz. The problem of existence is discussed for quasi-shear and quasi-longitudinal exceptional waves in three cut families of trigonal crystals: (0/spl deg/,/spl theta/,0/spl deg/), (90/spl deg/,90/spl deg/,/spl psi/) and (0/spl deg/,/spl theta/,90/spl deg/).