Experimental study of mode-coupling strength of AT-cut quartz resonators with high mesa step height

Bi-mesa resonators with very high mesa steps were fabricated and their frequency-temperature (f-T) characteristics measured as an index of the mode-coupling strength. The experimental results show that the rotation of the measured f-T data is in good agreement with calculation in the range of low mesa step height. At large mesa step height, where the coupling strength is very low in the calculation, the measured f-T curve is quite different from the curve of the pure thickness-shear mode. These results indicate the validity of mode-coupling and that choosing the minimal points in high mesa steps offers less advantage.