Fig. 3
From: Method for GHz optical helicity modulation by acoustic drum modes on a chip
Interferometric mapping of drum modes. (a) Sample configuration with ring sector-shaped BAWRs with three independent sections. (b,c) Acoustic maps of the surface displacement \(u_z\) obtained by exciting only the lower right BAWR (marked as \(V_\textrm{rf}\)) at the frequency of 1.5033 GHz and recording the \(u_z\)-component in phase and 180\(^\circ\) out-of-phase with the rf excitation. The nominal rf power applied to the lower right BAWR was 20 dBm. (d) Line profile of \(u_z\) along the dashed line in panel (a) showing that the short-period acoustic vibrations (i.e., the ones with ring-shaped wave fronts in b,c) are confined within the ZnO island.
