Investigation of surface leaky longitudinal waves on lithium niobate substrates

This paper focuses on studies of surface leaky longitudinal waves (SLLWs) on LiNbO/sub 3/ substrates. The theoretical results of searching SLLWs on LiNbO/sub 3/ in the range of Euler angles (0/spl deg/, /spl beta/, 90/spl deg/) and (/spl alpha/, 0/spl deg/, 0/spl deg/) are presented, which shows the velocity can be up to 6700 to 7300 m/s nearly twice that of normal SAW and has attenuation in the order of 10/sup -6/-10/sup -4/ dB//spl lambda/, however very low piezoelectric coupling coefficient (no more than 0.14%) in the range of Euler angles (0/spl deg/, /spl beta/, 90/spl deg/). The theoretical results also show that SLLWs, in the range of Euler angles (/spl alpha/, 0/spl deg/, 0/spl deg/) of LiNbO/sub 3/, have phase velocities 6500 to 7000 m/s and relatively high piezoelectric coupling coefficient (up to 0.6%). The experimental results at the Euler angles (0/spl deg/, 38/spl deg/, 90/spl deg/) and (16/spl deg/, 0/spl deg/, 0/spl deg/) on LiNbO/sub 3/ are also shown.