Optical Metasurfaces and Prospect of Their Applications Including Fiber Optics

Metasurfaces have emerged in the recent years as a platform to design subwavelength-thick optical components ("flat optics"), which can be used to implement any optical function (beam deflection, focusing, waveplates, etc). These flat optical components can be fabricated using a single lithographic step. The approach is particularly suited for patterning nonconventional substrates, such as semiconductor laser facets and optical fiber facets. In this paper, we review recent applications of metasurfaces to flat optical devices, including their use in semiconductor lasers and fiber optics. Metasurfaces make it possible to design all properties of light (amplitude, phase, and polarization), which enable us to build a large variety of flat optical components, including planar lenses, quarter-wave plates, optical vortex plates, holograms for vector beam generation, and ultrathin perfect absorbers and color coatings. We also review flat collimating lenses integrated on the facets of mid-infrared and far-infrared (terahertz) quantum cascade lasers, and novel techniques to create large arrays of nanostructures on fiber facets.