Structuring Light by Concentric-Ring Patterned Magnetic Metamaterial Cavities.

Ultracompact and tunable beam converters pose a significant potential for modern optical technologies ranging from classical and quantum communication to optical manipulation. Here we design and demonstrate concentric-ring patterned structures of magnetic metamaterial cavities capable of tailoring both polarization and phase of light by converting circularly polarized light into a vector beam with an orbital angular momentum. We experimentally illustrate the realization of both radially and azimuthally polarized vortex beams using such concentric-ring patterned magnetic metamaterials. These results contribute to the advanced complex light manipulation with optical metamaterials, making it one step closer to realizing the simultaneous control of polarization and orbital angular momentum of light on a chip.