Electrically tunable metasurface unit cell for dual function on – off intensity switching and phase-delay with multilayer structure working at 525 nm

An electrically tunable metasurface unit cell operating at 525 nm that enables dual-function optical modulation through on-off switching and continuous phase-delay control is discussed in this study. Tunable metasurfaces in the visible range are promising for compact wavefront-control devices, but achieving both high transmission contrast and a controllable phase response at low bias remains challenging. To address this gap, a multilayer unit cell architecture based on indium tin oxide (ITO), whose refractive index can be modulated by an applied bias voltage, is designed. The proposed structure enables simultaneous amplitude and phase tunability in the visible regime, particularly at low voltages. The structure further incorporates Al 2 O 3 and MgF 2 dielectric layers, with PEDOT: PSS serving as the attaching layer, to enhance the tunable optical response and transmission. Numerical results show that through the adjustment of the bias voltage, the unit cell is enabled to achieve transmission modulation from approximately 60% to 0% while providing full 2π phase-delay coverage. In addition, owing to the symmetry inherent in the phase-delay structure, the unit cell demonstrates a polarization-insensitive property. This work elaborates on the design details of the electrically tunable metasurface unit cell at an incident wavelength of 525 nm, laying the groundwork for wavefront-control applications such as beam steering and shaping at low bias voltages. Furthermore, these results demonstrate the feasibility of achieving voltage-controlled optical on–off switching and phase-delay modulation with nanostructures, providing a fundamental basis for designing reconfigurable photonic devices in the visible spectrum.