Research progress of active metasurfaces based on liquid crystals

The metasurfaces have the ability to precisely and efficiently manipulate the light wave at sub-wavelength scale. However, there are still many technical difficulties to be overcome when it comes to the realization of active control separately. The combination of liquid crystal (LCs) and metasurface is expected to give full play to their respective advantages to achieve a new type of active optical control device with high resolution, large diffraction angle and ultra-compact structure. The independent functional design of LC and metasurface was taken as the classification basis to review the research progress of active LC metasurfaces in recent years, which specifically included the combination of LC wave plate and polarization-sensitive metasurfaces, the combination of LC environment and resonant metasurfaces, and complementation of optical properties with LC and metasurface. Finally, the challenges and development prospects of active LC metasurface were discussed and prospected.