  Many applications of metasurfaces require an ability to dynamically change
their properties in time domain. Electrical tuning techniques are of particular
interest, since they pave a way to on-chip integration of metasurfaces with
optoelectronic devices. In this work, we propose and experimentally demonstrate
an electro-optic lithium niobate (EO-LN) metasurface that shows dynamic
modulations to phase retardation of transmitted light. Quasi-bound states in
the continuum (QBIC) are observed from our metasurface. And by applying
external electric voltages, the refractive index of the LN is changed by
Pockels EO nonlinearity, leading to efficient phase modulations to the
transmitted light around the QBIC wavelength. Our EO-LN metasurface opens up
new routes for potential applications in the field of displaying, pulse
shaping, and spatial light modulating.
