Electrically Tunable Optofluidic Metasurface

The dynamic control of light at the nanoscale has been a longstanding challenge in photonics. More recently, fluidics has been added to the toolkit, leveraging liquid properties as an additional degree of freedom for tunability. Here, we present a tunable metasurface architecture that integrates an optofluidic layer. We use a guided mode resonance platform, whereby a silicon nitride grating is coated with indium tin oxide (ITO) as the active material, operating in the visible-NIR wavelength range (∼800 nm). Our design employs an all-dielectric structure with a fluidic gate to overcome the efficiency-loss trade-off typical of other dynamic metasurfaces. We demonstrate spectral and phase tuning, achieving a near-2π phase shift with a low voltage swing (±3 V), as well as maintaining a strong resonance amplitude (R > 80%) with an all-pass filter configuration. These results establish a foundation for high-performance tunable metasurfaces with broad cross-disciplinary applications.