Thaxter J B, Carr P H, Silva J H
Rome Air Dev. Center, Hanscom AFB, MA.
IEEE Trans Ultrason Ferroelectr Freq Control. 1988;35(5):525-30. doi: 10.1109/58.8029.
Experimental measurements are reported on voltage-controlled acoustic time-delay lines operating at 1 GHz in the nearly pure shear-horizontal (S-H) mode in 38 degrees rotated Y-cut LiNbO(3). The high-acoustic velocity (4800 m/s) in conjunction with the large electroacoustic effect exhibited by this orientation allows high-frequency operation and optimum time-delay tuning sensitivity with a planar, single surface, device geometry. The authors demonstrate fractional time delay of 0.3x10(-6) V(-1 ) for surface electrodes that produce an in-plane E-field. However, the simultaneous excitation and propagation of both a leaky surface-acoustic wave (LSAW) and surface skimming bulk wave (SSBW), both as (nearly pure) S-H waves in these devices, seriously restricts the extent to which it is possible to maximize the time delay modulation sensitivity by reducing electrode gap spacing as done in similar SAW devices. The LSAW and surface-skimming body wave (SSBW) propagate at nearly the same velocity on a free surface, and perturbation of their velocity and relative attenuation rates by surface electrodes causes pronounced interference effects between the two modes for some device geometries.
报道了在38°旋转Y切LiNbO₃中以近纯水平剪切（S - H）模式在1 GHz下工作的压控声延时线的实验测量结果。这种取向所具有的高声速（4800 m/s）以及大的电声效应，使得采用平面、单表面器件几何结构时能够实现高频运行和最佳的延时调谐灵敏度。作者展示了对于产生面内电场的表面电极，分数延时为0.3×10⁻⁶ V⁻¹。然而，在这些器件中，泄漏表面声波（LSAW）和表面掠射体波（SSBW）作为（近纯）S - H波同时激发和传播，严重限制了像在类似声表面波（SAW）器件中那样通过减小电极间隙间距来最大化延时调制灵敏度的程度。LSAW和表面掠射体波（SSBW）在自由表面上以几乎相同的速度传播，表面电极对它们的速度和相对衰减率的扰动会在某些器件几何结构中导致两种模式之间产生明显的干涉效应。
