Energy confinement time of leaky Lamb wave in interdigital transducers

A new phenomenon which suggests energy confinement for a definite time inside interdigital transducers (IDTs) is shown quantitatively. Two IDTs are used to generate and reflect a leaky Lamb wave, respectively, in a piezoelectric substrate from which a longitudinal wave is radiated into the contacting acoustooptic (AO) medium. Optical measurement of the radiated wave using the AO interaction clarifies the interference effect inside the IDT and suggests the “energy confinement time” of about 50 μs per one IDT. This effect cannot be observed by measuring the admittance in the case of the non-leaky wave: this effect can be observed first electromechanically in the case of the leaky wave