Influence of nonparallelism of the surfaces of a piezoelectric layer on the frequency band of an electroacoustic piezoelectric transducer

The influence of nonparallelism of the surfaces of a piezoelectric transducer on its impedance and frequency band is analyzed theoretically. The model of a wedge-shaped piezoelectric layer taken for the analysis consists of a set of n plane-parallel elements arranged in succession along the length of the transducer with a gradual increase in the thickness of the piezoelectric layer. The analysis performed demonstrates the possibility of significantly expanding the band of working frequencies of a piezoelectric transducer when its electroacoustic conversion efficiency is reduced. In some cases, however, a decrease in conversion efficiency can be employed to optimize an acoustic device, for example, in creating a filter-type piezoelectric transducer, where electromagnetic energy is converted into acoustic energy successively from one cell of the filter to another. The proposed method for expanding the frequency band can be useful, for example, in creating high-frequency acousto-optic Bragg cells. Zh. Tekh. Fiz. 69, 72–73 (March 1999)