4pPA13. Theoretical and experimental investigation for LFB acoustic microscopy characterization of proton-exchanged LiTaO[inf 3] optical waveguides.

Session: Thursday Afternoon, December 5

Time: 5:00

Author: Masahito Miyashita
Location: Dept. of Elec. Eng., Tohoku Univ., Sendai, 980-77 Japan
Author: Jun-ichi Kushibiki
Location: Dept. of Elec. Eng., Tohoku Univ., Sendai, 980-77 Japan


Line-focus-beam (LFB) acoustic microscopy has been recognized as a new analytical technique of quantitative material characterization, by measuring the phase velocities of leaky surface acoustic waves (LSAWs) excited on the water-loaded specimen surface. Recently, application of this ultrasonic technique has been demonstrated successfully for characterization of proton-exchanged layers for LiNbO[inf 3] and LiTaO[inf 3] optical waveguides and for evaluation of the device fabrication processes. It is necessary and important to calculate LSAW propagation characteristics, viz., velocity and attenuation, for interpretation of experimental results and for evaluation of physical properties, such as optical and elastic properties, in proton-exchanged layers. In this paper, LSAW propagation characteristics for the structural model of water/piezoelectric layer/piezoelectric substrate are analyzed. The propagation characteristics are interpreted with calculations of spatial distributions of mechanical displacements and electric potential. Specimens of Z-cut LiTaO[inf 3] substrates, with a layer thickness of 0.5 (mu)m, were prepared. Experimental data of LSAW propagation characteristics, measured in the frequency range 100 to 300 MHz, are discussed in detail comparing with the calculated results.

ASA 132nd meeting - Hawaii, December 1996