Tunable Helical Surface Acoustic Waves

2025 DAAD RISE Internship at the Paul Drude Institute in Berlin, Germany researching the generation and detection GHz SAWs with tunable OAM on piezoelectric devices

Overview

During Summer 2025, I was a research intern at the Paul Drude Institute in Berlin, Germany, on a team researching the generation and detection of helical surface acoustic waves. Such waves are of interest because the dynamic control of circular light polarization has enabled advancements both in fundamental research and applied technologies. At GHz frequencies, such control exploits interactions with helical surface and bulk acoustic waves in solid-state platforms. For full optomechanical control, simultaneous modulation of light amplitude and orbital angular momentum, we aim at transfer of angular momentum from piezoelectrically driven helical mechanical waves to the optical field. The central challenge is precise generation and detection of helical acoustic waves, requiring a tunable mechanical field. Our device consists of six interdigital transducers arranged circularly on a piezoelectrically active ZnO film deposited on sapphire. Phase-delayed excitation enables the generation of vortices with controllable rotation. My contributions include device design optimization, fabrication, electrical and interferometric characterization, and refinement of experimental methodologies.

Simulation GIFs

CW — Config

CW — Simulation

CCW — Config

CCW — Simulation

In-phase — Config

In-phase — Simulation