Metasurfaces are ultrathin-film optical elements that can manipulate the amplitude, phase, and polarization of light. The need to minaturise optical elements has generated a significant research effort on the realisation of flat structures to focus light such as subwavelength gratings and metamaterials. To date, most of these structures manipulate a linearly polarised incident beam, whereas the use of radially or azimuthally polarised light offers important advantages. In this work, we use metasurfaces to simultaneously convert linearly polarized incident light into an azimuthally polarized optical vortex and focuses the at a distance approximately equal to the wavelength of the incident light.
Liam O’Faolain leads the Nanophotonics Group at the Centre for Advanced Photonics and Process Analysis. His research group focuses on developing efficient lasers and innovative sensors based on nanophotonics and integrated photonics, see www.cappa.ie . He is the author/co-author of more than 100 journal papers. His ”h”-factor is 48. He is currently supervising 13 PhD students and 5 postdoctoral research fellows. He co-ordinates the ERC Proof of Concept project HERCULES, the OPTHAPHI Marie Curie European Joint Doctorate project (https://www.optaphi.eu/) and the H2020 PASSEPARTOUT project (https://www.passepartout-h2020.eu/).