Combination of Tetragonal Crystals With LiTaO3 Thin Plate for Transverse Resonance Suppression of Surface Acoustic Wave Devices.

This article discusses combination of tetragonal crystals with LiTaO3 (LT) thin plate for complete transverse resonance suppression of surface acoustic wave (SAW) devices without k2 deterioration by manipulating the slowness shape. Besides, better lateral energy confinement is achieved as well by the use of a double bus-bar structure. First, the mechanism of slowness shape manipulation by combining tetragonal crystals is studied. By comparison, YZ-lithium tetraborate (LBO) shows better performance than 69°Y90°X quartz. Then, numerical simulations are carried out using a periodic 3-D finite method assisted by a hierarchical cascading technique (HCT), and the effectiveness of transverse mode suppression by flattening the slowness shape is revealed. Also, the possibility to realize temperature compensation (TC) is discussed owing to the unique material property of LBO. Moreover, the capability of other tetragonal crystals for slowness manipulation is compared, and LBO is the best choice among these tetragonal crystals.