Pure shear horizontal SAW on langatate

In this paper we discuss for the first time the characteristics of the shear horizontal (SH) mode on langatate, a trigonal class 32 substrate just like quartz, which exhibits this same symmetry type uncoupling for the Euler angles [0° θ 90°]. We present experimental results for phase velocity and coupling along the orientation with Euler angles [0° 132° 90°], noting that a phase velocity reduction of about 50% is observed when compared to 36° Y rotated quartz, thus leading to smaller STW devices than on quartz. Our experiments show that this mode has a deep penetration inside the substrate, in accordance with theoretical predictions. The existence of plate modes and reflections from the back surface, and the procedures used to significantly reduce these interferences are reported. We also include experimental results on the fractional change in frequency with respect to temperature (Δf/fo) and the temperature coefficient of delay, TCD, for the Euler angles [0° 132° 90°] orientation. Our experimental data, obtained from direct measurements on a SAW wafer, are in excellent agreement with theoretical analysis for the Euler angles [0° θ 90°] plane