A Compound Phase-Modulated Beam Splitter to Distinguish Both Spin and Orbital Angular Momentum

Based on a phase-modulated metallic nanoslit array, an angular momentum (AM) beam splitter has been demonstrated to distinguish both spin and orbital components carried by the light beam. With such a device, the AM modes could be coupled into nondiffracting surface plasmonic beams propagating toward different directions. According to the experimental results, the extinction ratio for spin AM beam splitting is larger than 10 and the spatial interval of adjacent orbital AM modes (with a topological charge interval of 2) is more than 1.1 mu m. We believe that such a device would have great potential to achieve a highly compact photonic integrated circuit with the plasmonic beam.