Mechanical methods to modulate light are among the most effective approaches and have served as a standard since the founding of the field of optics. However, they typically require moving large optical elements, leading to inherently slow response times. Reducing the size of these mechanical components is the most direct route to increasing speed, yet while Micro-Electromechanical Systems (MEMS) have advanced significantly with modern nanofabrication techniques, they remain limited to modulation frequencies of only a few MHz. Acoustic waves, in contrast, are one of the fastest forms of mechanical modulation, but their small displacements have traditionally not been sufficient to induce significant changes in the optical properties. Here, we introduce a nanophotonic opto-mechanical resonator that confines light to the same length scale as typical GHz acoustic displacements. By constructing the resonator from mechanically compliant rubber materials and harnessing an optical plasmon mode, we deform the optical mode shape and energy with surface acoustic waves. This approach enables a substantial resonance shift—from approximately 700 nm to 600 nm—and modulations at frequencies approaching 1 GHz. Moreover, we demonstrate that the acoustic excitation can be sculpted to produce complex dynamic optical amplitudes and phases over the device surface, enabling beam steering and lensing functionalities without the need for moving large optics. These results represent a significant advance in acousto-optic modulation, offering a versatile platform for both ultrafast modulation and precise material manipulation at nanometer and nanosecond scales. By scaling optical cavities to dimensions compatible with GHz acoustic excitations, our technique paves the way for a new generation of high-speed optical metasurfaces.

Skyler Selvin is a PhD candidate in Electrical Engineering at Stanford University, advised by Professor Mark Brongersma. He received his BS in Electrical Engineering from UCLA and MS in Electrical Engineering from Stanford. Prior to beginning his doctoral studies, he worked at HRL Laboratories as a development engineer, creating mechanically modulated low-frequency transmitters using magnetics. He then spent time at Tsinghua University, where he contributed to the development of novel RF-based contrast methods for photoacoustic imaging systems. Skyler’s current research focuses on nanophotonics and dynamic photonic devices, leveraging MEMS, acoustics, and soft materials to achieve mechanical modulation. Beyond his core work in nanophotonics, he is dedicated to designing ultra-low-cost solar solutions and electronic systems for rural communities in sub-Saharan Africa.