Dielectric metasurfaces enabling twisted light generation/detection/(de)multiplexing for data information transfer.

Abstract

We propose, design, fabricate and demonstrate nanophotonic all-dielectric metasurfaces enabling the generation, detection and (de)multiplexing of twisted light having helical phase structure and carrying orbital angular momentum (OAM). The designed metasurfaces are based on dielectric elliptical resonators on standard silicon-on-insulator (SOI) platform. One can achieve full-phase control of 0-2π and flexible amplitude adjustment by properly changing the geometric dimensions (long axis, short axis) and orientation of dielectric elliptical resonator based on the Mie resonance effect. Using the designed and fabricated all-dielectric metasurfaces, we demonstrate the generation and detection of OAM beams with topological charge number from l = -4 to 4. The crosstalk matrix of generated OAM beams is also characterized showing -16 dB crosstalk. We further demonstrate the (de)multiplexing of two OAM beams (OAM+1 & OAM+4 or OAM+2 & OAM+3) each carrying a binary image ("A" & "B" or "HUST" & "WNLO"). The obtained results show error-free data information transfer with favorable performance. The presented alternative approach of all-dielectric metasurfaces shows distinct features of easy fabrication process and easy chip-scale integration facilitating ultrathin optical applications. The demonstrations may open a door to find more interesting applications in all-dielectric metasurfaces enabled spatial light manipulation and optical communications and interconnects.