A single gold metasurface design capable of generating vortex beams with different topological charges

A simple approach is proposed to generate vortex beams using a metasurface composed of 31x31 array of sub-wavelength sized rectangular apertures in a ultrathin gold film. It operates at broadband (800 similar to 2000 nm) covering telecom wavelengths, topological charges of resultant vortex beams are from -4 to +4 and weight coefficient of the desired charge exceeds 0.95 under the incidence of circularly polarized light. Simulation results show that this design is logically coincidence. The designed metasurface also has advantage of favorable fabrication tolerance and may be a potential candidate in integrated optical communication system in future.