An electrically tunable metasurface for continuous phase modulation at visible wavelength based on indium tin oxide

Electrically tunable metasurfaces have great potential for flexible response and high precision in wavefront control, making them highly applicable. However, there is currently a scarcity of electrically tunable metasurfaces working at visible wavelengths. An electrically tunable transmission metasurface working at 660nm was proposed in this paper. The metasurface integrates a transparent conductive oxide material ITO as a tunable electro-optical material. The design scheme of the electrically tunable metasurface is based on the classical Drude model. In the electric field, the variation of carrier concentration in the accumulation layer induced by bias voltage can enhance the nonlinear optical response and improve light field modulation effect. The proposed metasurface is structured with four symmetrically distributed rectangular patches nested with a circular ring. In addition, the phase modulation capability of this model has been theoretically analyzed. With a bias voltage of -4.9V~20V, a continuous transmission phase delay between 0°~191.45° at a wavelength of 660nm can be achieved. The proposal of the electrically tunable metasurface structure establishes a new means for transmitted beam wavefront shaping and modulation, and in the future, the metasurfaces designed with a continuous phase modulation at visible wavelength will suggest more applications in naked-eye 3D display, holographic imaging, and other fields.