On the interaction of temperature gradients with surface wave propagation in anisotropic solids

An analysis of the transient thermal response of surface acoustic wave (SAW) resonators subject to various temperature inputs to the bounding surfaces is presented. Computational results indicate that thermal transients or dynamic frequency spikes are observed only at and around turnover temperatures. Generally, the magnitude of dynamic frequency undershoot or overshoot is on the order of 1-100 parts per billion for a 1 C step change in the external surface temperature. Temperature gradients can produce dispersion in surface wave propagation. However, a SAW device with large thickness/wavelength ratio placed symmetrically in a longitudinal temperature gradient will exhibit minimal amount of dispersion in the transient state. Since a dispersive propagation of surface waves leads to a degradation of the resonator stability, it must be avoided for increased stability of the device.