Controlling vector beams with anisotropic metamaterials

Structured light is important in various fields including metrology, optical trapping, communications, and nonlinear optics. Here, we introduce a method to manipulate cylindrical vector beams using a strongly anisotropic epsilon-near-zero metamaterial. The longitudinal and transverse fields of a vector beam interacts differently with the metamaterial due to its anisotropy with an efficiency which depends on the numerical aperture of the objective, the initial state of polarisation and the quality of the metamaterial. These anisotropic interactions lead to reshaping the vector beam and its polarisation as demonstrated experimentally and theoretically. The approach facilitates wave front shaping and spatial polarization engineering, promising applications in microscopy, information encoding, and biochemical sensing.