Four-Wave Mixing Holographic Multiplexing Based on Nonlinear Metasurfaces

Metasurfaces are utilized to realize computer-generated holograms (CGHs), with excellent wavefront shaping ability and ultrasmall footprint. To increase the information capacity of metasurface holograms, smart multiplexing techniques together with suitable designs are highly demanded. However, so far only a few approaches to achieve nonlinear metasurfaces holographic multiplexing based on CGHs are proposed, due to limited freedoms of multiplexing and proper metasurfaces' design. The nonlinear interaction of light with the metasurface can generate new frequencies compared to the input laser beam, which is promising to realize spectral and spatial multifunctional wavefront manipulation. Here, a four-wave mixing (FWM) holographic multiplexing technique is numerically proposed using a nonlinear metasurface composed of a nanoapertures array. It is demonstrated that the complex amplitude modulation by such a metasurface through the FWM process can be utilized for amplitude-only CGHs, which can process significantly independent information at different nonlinear frequencies in the optical regime. Utilizing the spatial and spectral multiplexing of nonlinear metasurfaces holography, they can be found applications for multidimensional holographic displays and can provide enhanced security for optical data storage. These results show that nonlinear metasurfaces are promising for applications of arbitrary frequency conversion and optical encryption and anticounterfeiting designs.