Visualization of Gaussian Mode Profile in Gigahertz Surface-Acoustic-Wave Resonators

Abstract

Surface-acoustic-wave (SAW) resonators operating at gigahertz (GHz) frequencies are widely used in wireless telecommunication and quantum information processing. Successful implementation of such resonators calls for detailed microscopic understanding of their mode profiles, energy dissipation channels, and imperfections from microfabrication. In this work, we report on the visualization of acoustic waves in LiNbO3 SAW resonators by transmission-mode microwave impedance microscopy (TMIM). The Gaussian mode profile tightly confined by reflecting mirrors is vividly seen in the TMIM images, from which the linewidth of the resonator itself can be extracted. The spatially resolved acoustic profile also allows us to perform failure analysis on faulty devices. Our work establishes a pathway for further optimization of SAW resonators for classical and quantum acoustic applications.