Electro-optical modulation of light polarization in a nonlocal lithium niobate metasurface

We report the experimental realization of a LiNbO3 metasurface for electro-optic modulation of light polarization in the telecommunication C-band. High quality factor quasi-bound states in the continuum are employed to enhance the modulation of the amplitude and phase of an impinging beam by a driving electric field, leading to efficient polarization rotation and conversion. We quantified modulation effects under a CMOS-compatible bias at 1 MHz frequency, achieving variations of 5% in the Stokes parameters and a variation of the polarization ellipse angles of about 3° for the transmitted light. These results demonstrate that dynamic polarization and phase modulation can be attained in a compact platform, highlighting the potential of high-quality resonant LiNbO3 nonlocal metasurfaces for enhanced light–matter interaction in subwavelength electro-optic devices.