부산대학교 도서관

The development of optical metamaterials enabled new light–matter interaction effects based on nano-structural engineering rather than the natural properties of the constituent materials. This facilitated applications unachievable with natural materials; however, practical applications of the proposed three-dimensional devices are limited by costly and complicated fabrication. In addition, many experimental realizations of metamaterial-based devices suffer from large losses due to metal inclusions. Recent research approaches have evolved to deal with these challenges on both the structural and the material levels. The rise of optical metasurfaces and the inclusion of alternative plasmonic materials compose two complementary approaches that have recently emerged to improve metamaterial devices, or metadevices. Metasurfaces have enabled a whole new family of planar optical devices through wavefront engineering of light. They are easily assembled and more suitable for on-chip fabrication. Simultaneously, other plasmonic materials including highly doped semiconductor oxides and metal nitrides have extended the spectral performance of plasmonic structures and have realized novel concepts such as epsilon-near-zero operation. They can also meet application-specific challenges associated with high power signals and local heating. In addition, their tunable optical properties enabled by free carrier modulation provide a strong avenue to build active metasurfaces and metadevices.