Optical Information Multiplexing with Nonlinear Coding Metasurfaces

Coding metasurfaces, as a new type of design concept, have provided many attractive functionalities for manipulating the wave fronts of light. Previous research only focused on linear coding metasurfaces; however, with the increasing demand for highly integrated and compact multifunctional chips, the drawbacks of linear coding metasurfaces, the constraints on information capacity and operating frequency are becoming more and more obvious. Here, Pancharatnam-Berry-phase-based nonlinear coding metasurfaces are proposed, in which convenient digital signal processing is employed to design multidimensional information channels in nonlinear optical processes to achieve optical information multiplexing. In order to confirm the feasibility of this methodology, by encoding various focusing functionalities and image information into nonlinear metasurfaces, a multifocal metalens and a multifunctional metasurface are theoretically designed, and their excellent performances are experimentally demonstrated. The proposed nonlinear coding metasurfaces may provide a promising platform for information encryption, multi-channel optical data storage, and real space encoding imaging.