Transformation of OAM Waves to Plane Spiral OAM Waves Based on Gradient-Index Meta-Surface

The conventional Orbital Angular Momentum (OAM) waves, which propagate along the main axis are transformed into the plane spiral OAM waves based on Gradient index Meta-surface. The cell of the meta-surface contains three layers with a metallic `H', a dielectric spacer and a metal plate. Using the radial arrangement of the metallic `H' cells, the conventional OAM waves can be transformed into the plane spiral OAM waves when they normally illuminate on the meta-surface. Thus, multiple OAM beams can be converted into the corresponding PSOAM beams using the same meta-surface and be superposed to realize the structured EM waves.