Dynamic characterization of in-plane bulk acoustic resonators using high-sensitivity optical reflection measurements

Abstract

Two experimental techniques for measuring dynamic displacement and strain for in-plane bulk acoustic resonators are presented. These techniques, optical knife-edge and photoelastic measurements, can characterize in-plane high-frequency vibrations with a degree of precision and simplicity that has not been shown previously with MEMS. The measurements are spatially resolved and can be used to reconstruct the vibrational mode shape of the resonator. Experimental results presented here are acquired using both methods on a single crystal silicon bulk acoustic resonator (SiBAR) with a fundamental resonance frequency of ≈ 13.6 MHz.