Metasurfaces 2.0: Laser-integrated and with vector field control

Abstract

The past decade has witnessed the rapid development of metasurfaces. In this paper, we outline our thinking on what we regard as two important trends in metasurface research, namely, the continual improvement in the light field modulation capacity of metasurfaces and the integration of metasurfaces with other devices to achieve fully contained optical systems. We first describe one of the fastest growing branches of the former, which is known as metasurface-based vectorial holography. This aims to control the wavefront and the polarization state of a light beam simultaneously. In comparison with single function devices, i.e., those that modulate the wavefront or polarization but not both, metasurface vectorial holography represents a significant improvement in our ability to modulate light fields. We then discuss the integration of metasurfaces with lasers for the goal of direct modulation of the polarization of the output beam or for the generation of beams with tailored orbital angular momenta. Two methods for doing so are discussed, namely, on-facet integration and in-cavity integration. We hope this Perspective will provide readers with new insights and thus help extend applications of metasurface-based optical devices.