Multilayer systems driven by elastic standing waves

An elastic standing wave propagating in a cubic piezoelectric multilayer structure, parallel to or at an angle with the direction of growth, induces a standing wave of strains. which results in a standing wave of piezoelectric fields. The thickness of each layer is chosen equal to half the wavelength in that layer. This choice corresponds to ail even-order zone-center folded acoustic mode with zero minigap. The field will, produce an ac voltage signal across the system at the frequency of the wave. We have found that in well-known systems grown along: [111] with a thickness of 2 mu m per period, the amplitude of the signal induced by a longitudinal standing wave can be of the order of a few volts; for an energy-flux density of 0.1 W/cm(2). As an ultrasonic receiver, this system is expected to have higher sensitivity than general transducers. Infrared light modulators operating in the range of GHz are also discussed as a possible application of the same system.