Polarization-multiplexed three-channel dielectric metasurfaces integrated with liquid crystals for holographic displays

Multi-channel metasurface holography based on polarization multiplexing has received close attention for its application in increasing information capacity. However, most of the existing spin-selective metasurfaces focus on the utilization of the cross-polarized channels while neglecting the co-polarized channels. Moreover, the real-time dynamic switching of the incident polarization of the metasurface remains a great challenge. This work presents a dielectric metasurface that combines geometric and propagation phase modulations. It allows phase control of a pair of orthogonal circular polarizations. A liquid crystal (LC) film is placed at the bottom layer of the metasurface to achieve dynamic switching of the incident polarization of the metasurface. As a proof-of-concept, we design and simulate a dielectric metasurface integrated with liquid crystals (LCs) for three-channel holographic displays. The LCs modulate the incident linear polarization into two orthogonal circular polarizations and illuminate the metasurface. The metasurface displays one holographic image in the vertical direction from the co-polarized channel and two holographic images at certain angles from the cross-polarized channel. It means that three holographic images can be displayed simultaneously without overlapping for linearly polarized (LP) light. Our design and simulations could provide a new, to our knowledge, scheme for multi-channel holography and active tunable metasurfaces.