Two-dimensional (2D) metamaterials or known as metasurfaces have attracted researchers’ attention due to their capability to manipulate the amplitudes, phases and polarization states of incident electromagnetic waves by conferring extra phase different phase at different positions through a super cell that is composed of different oriented structures. In other words, metasurfaces can achieve beam steering and wave shaping by imparting local, gradient phase shift to the incoming waves. With these abilities, metasurfaces can be applied to applications such as ultrathin invisibility cloaks, metasurface holograms, planar lenses and a vortex generator. With the above mentioned advantages and applications of metasurfaces, yet, all the demonstrated metasurfaces possess a main insufficiency that once the metasurfaces are designed and fabricated, their optical properties are then fixed without any chance for further manipulation, which limits their versatility in practical applications. Moreover, although some researchers employed dynamically changeable materials to achieve an active metasurface, such manipulation can only change the overall performance such as an operating frequency instead of changing the provided phase on each pixel of a metasurface. To solve this issue, we employ liquid crystal integrated with a metasurface and the combination could be thus be dynamically tuned via electric bias on each pixel of liquid crystals. Through this setup, we can alter the polarization state of the incident electromagnetic wave dynamically and thus manipulate the extra phase provided by each pixel. In this combination, liquid crystal is employed to change the incident polarization from 0 to 360-degree and the metasurface is designed to achieve four different output signals including phase modulated linear- and circular-polarized light and amplitude-modulated linear- and circular-polarized light. Meanwhile, the metasurfaces could also control the transmission efficiency of the device.
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