Metasurface around the side surface of an optical fiber for light focusing

Optical fibers integrated with metasurfaces have drawn tremendous interest in recent years due to the great potential for revolutionizing and functionalizing traditional optics. However, in most cases, metasurfaces have been placed on the fiber end-facet where the area is quite limited. Here, by dressing a series of identical dielectric rings around the side surface of the microfiber and adjusting their positions along the microfiber axis, we extracted guided waves into free-space radiation with continuously controllable phase shift and achieved circular-arc-shaped line focusing. We demonstrated that the off-fiber foci could be rotated around the fiber axis by tuning the polarization of the guided waves. In addition, we demonstrated that the shape of the focus could be further tuned by introducing symmetry breaking into the dielectric rings. Our study provides a new dimension for the design of optical fiber devices decorated with metasurfaces.(c) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

This study demonstrates the design potential of optical fiber devices by integrating metasurfaces on the side surface of microfibers. The controllable phase shift and focusing effects are achieved by adjusting the positions of the dielectric rings and the polarization of the guided waves.