Optical vortices —light structures which look like donuts and can rotate around their axis of propagation— have attracted wide interest as new means for free space communications, optical trapping, and structured illumination in microscopes. Current wavefront shaping methods, however, can only provide limited control over the vorticity and the polarization (photon’s spin) of those beams in 3D space, thus limiting their application. In this study, we introduce a new type of metasurfaces which can generate complex optical vortices in which both the vortex strength and polarization state can be remotely controlled, on demand, along the optical path of the beam. Our metasurfaces are polarization-tunable and, hence, can produce different vortex profiles by switching the input polarization. This can bring new degree-of-freedom for applications such as light-matter interaction, high resolution microscopy, and sensing.
November 18, 2021