Leaky waves and the elastic wave resonance reflection on a crystal-thin solid layer interface. II. Leaky waves given rise to by exceptional bulk waves

Abstract

A study is made of the elastic wave resonance reflection in a crystal-thin solid layer structure near the velocity of a leaky wave which originates from an exceptional bulk wave. The latter is a homogeneous mode with group velocity parallel to the boundary of a medium which satisfies the condition of the mechanically free surface. On the surface coated with a thin layer, the exceptional bulk wave can transform into the leaky wave and then there arises a narrow interval of incident angles where the coefficients of mode conversion suffer abrupt and strong variations in phase and magnitude. A criterion of occurence of the leaky wave is found. Approximate expressions describing the behavior of the coefficients of mode conversion within the resonance interval of incident angles are derived and analyzed.