Twisting Light with Metamaterials

The discovery of optical vortex beams has opened a new area of optical physics and led to new understanding of a wide range of phenomena, particular when bridging with the emerging technologies of metamaterials. At nanoscale, passive approaches and devices have been proposed for generating twisted light and enable orbital angular momentum (OAM) related unconventional light‐matter interactions at both the far‐field and near‐field. By integrating active materials and optical cavities with OAM beam generators, micro‐ and nanoscale OAM laser sources can be realized, providing tunable topological charge and desired polarization properties. In the last part, interactions between OAM beams with engineered nonlinear colloidal suspensions are discussed, which show a great promise for applications such as biological and chemical imaging.