| (a) A liquid-crystal metasurface (LCMS) acts as a patterned waveplate which modifies a controlled fraction of the beam transverse polarization profile by adding conjugate phases to the two circular polarization components. Based on this mechanism, a minimal set of three LCMSs can be adopted to simulate arbitrary unitary operations in a discrete two-dimensional space. (b) This space is populated by circularly polarized optical modes carrying a quantized amount of transverse momentum along two orthogonal directions, which can be resolved on a camera placed in the focal plane of a lens. (c) When computing the liquid-crystal patterns required for a specific simulation, the obtained solutions typically feature numerous discontinuous jumps. An automated routine is executed to remove all discontinuities except isolated vortices that can be tolerated in the fabricated devices. Credit: Ammendola, Di Colandrea, et al., doi 10.1117/1.AP.7.1.016006 |
