Solidly Mounted Resonator with Optimized Acoustic Reflector

The quality factor (Q) of the Solidly Mounted Resonator is limited by acoustic losses caused by waves leaking through the mirror stack. Traditionally employed acoustic mirror reflects only longitudinal waves and not shear waves. Starting with the stop-band theory and the principle of spacer layers in Optics, we present a design procedure which gives the modified thicknesses for the reflector stack to efficiently reflect both the waves. FEM simulations were performed for verifying the results based on the analytical model described in showing good agreement. With the optimized design, we can obtain a minimum transmission for longitudinal and shear waves of -25 dB and -20 dB at resonant frequencies for longitudinal and shear waves, respectively, for various reflector material combinations. With such optimized designs, devices can be designed that are no more limited by acoustic loss into the substrate.