Broadband and High-Efficiency Multi-Tasking Silicon-Based Geometric-Phase Metasurfaces: A Review

Silicon (Si)-based geometric phase metasurfaces are fantastic state-of-the-art light field manipulators. While the optical metasurfaces generally excel in the micro-control of light with supreme accuracy and flexibility, the geometric phase principle grants them the much-desired broadband phase manipulation property, free from material dispersion. Furthermore, adopting Si as their fundamental material serves as a critical step toward applicable practice. Thanks to the optical lossless feature and CMOS compatibility, Si-based metasurfaces are bestowed with high efficiency and fabrication conveniency. As a result, the Si-based metasurfaces can be perfectly integrated into Si-based optoelectronic chips with on-demand functions, trending to replace the conventional bulky and insufficient macroscopic optical devices. Here we review the origin, physical characteristics, and recent development of Si-based geometric-phase metasurfaces, especially underscoring their important achievements in broadband, high efficiency, and multitasking functionalities. Lastly, we envision their typical potential applications that can be realized in the near future.