Measurement of BAW radiation from low-loss LSAW resonators

The first direct experimental observation of bulk-acoustic wave radiation f rom a leaky surface-acoustic wave transducer, measured arriving at the back side of the piezoceramic substrate, is reported. A scanning laser-interfero metric probe is used to map the spatial distribution of the bulk-wave radia tion patterns on the substrate bottom. The different energy-flow angles int o the substrate are obtained as functions of frequency and used to identify the corresponding bulk-wave modes arriving at the substrate bottom.