Review on phase control principles, new function expansion and frontier applications of metasurfaces

Abstract

Metasurfaces based on phase modulation mechanisms, including geometric and propagation phases, have enabled precise control of the amplitude, phase, and polarization of optical fields at the subwavelength scale, providing an important foundation for the development of planar and integrated optical systems. As research has progressed, liquid-crystal-assisted metasurfaces have introduced dynamically tunable functionalities, allowing continuous and real-time manipulation of optical wavefronts. At the same time, nonlinear metasurfaces have offered alternative approaches to overcoming some of the limitations associated with conventional nonlinear optical devices, such as strict phase-matching requirements and bulky system architectures. These developments have expanded the possibilities for applications including ultrafast pulse modulation, nonlinear frequency conversion, and temporal control of light fields. Benefiting from their ultrathin geometry, flexible design strategies, and compatibility with integrated platforms, metasurfaces have been widely investigated as compact alternatives to conventional optical components in areas such as imaging, holography, and beam steering. Their potential has also attracted growing attention in emerging fields, including ultrafast photonics, optical communications, quantum optics, and optical manipulation at the micro- and nanoscale. In many cases, metasurface-based devices can reduce system complexity while enabling optical functionalities that are difficult to realize using traditional bulk elements. Despite these advances, several challenges remain. Dynamic modulation speed, nonlinear conversion efficiency, largearea fabrication with high uniformity, and the balance between broadband operation and high efficiency continue to be important issues. Addressing these limitations will be essential for the wider adoption of metasurface technologies in practical systems and integrated photonic platforms. Further progress in material engineering, nanofabrication techniques, computational design methods, and interdisciplinary research is expected to support the continued development of the field. In this context, metasurfaces are likely to play an increasingly important role in areas such as integrated photonics, ultrafast optics, quantum information processing, next-generation optical communications, and biophotonics.