Excitation of Surface Acoustic Wave on a Glass Substrate Using a LiNbO₃ Piece

Abstract

Surface acoustic waves (SAWs) are used in many applications. Here, we consider application of SAWs to actuators, which require relatively large vibration amplitudes. In conventional applications, a SAW propagates on a LiNbO₃ substrate that serves as an elastic medium. This implies that the maximal size of a SAW transducer is limited by the LiNbO₃ wafer size. Better actuators require larger-size SAW transducers. Here, we propose a transducer in which an excited SAW propagates on an inexpensive elastic medium (indirect excitation method). The method combines a piezoelectric material and a non-piezoelectric material substrate. These two materials are coupled. Electric energy is provided by an interdigital transducer (IDT). We designed and studied three different transducer configurations. To determine the optimal configuration, various materials and their combinations were considered with the proposed method. Electrical and mechanical characteristics were quantified in terms of the frequency response of admittance and vibration response, respectively. A suitable combination of materials was determined after measuring and analyzing the properties of different transducers. For this combination, the vibration velocity of the novel transducer was as large as that obtained using the conventional direct excitation method.