Leaky-Surface-Acoustic-Wave Properties on Reverse-Proton-Exchanged LiNbO3

概要

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A proton-exchanged (PE) layer with an elastically soft property can be buried into a substrate by a reverse proton exchange (RPE) process. It is expected that an RPE layer with a property similar to that of bulk LiNbO3 will prevent the degradation of coupling factor, and that the buried PE layer will change the anisotropy of the substrate effectively and reduce the leaky surface acoustic wave (LSAW) attenuation as compared with bulk LN. In this study, first, a layered structure of air/bulk LN/softened LN was assumed for rotated Y–X LN and LSAW attenuation was calculated. By controlling the elastic constant of the softened LN, the rotation angle from the $Y$-axis giving zero attenuation shifted from 64 to 5° for a metallized surface, and the rotation angle at which the attenuation decreases as compared with bulk LN was drastically changed for a free surface. Next, the LSAW propagation loss $\mathit{PL}$ was measured on 41° Y–X LN. The $\mathit{PL}$ for the metallized surface was decreased by carrying out the RPE process from 0.036 dB/$\lambda$ of a virgin sample to 0.015 dB/$\lambda$. The decrease in $\mathit{PL}$ for the free surface was also observed.
2009-07-25