Figure 2: Experiment of OAM and polarization multiplexing in a free-space mm-wave communication link.
From: High-capacity millimetre-wave communications with orbital angular momentum multiplexing
(a) Schematic diagram of a millimetre-wave link based on OAM and polarization multiplexing. (b) Polarization-multiplexed (pol-muxed) OAM beams (ℓ=−3, −1, +1 and +3) are generated by dual-polarization lensed-horn antennae, followed by SPPs. These beams are multiplexed by a 1 × 4 combiner (three beamsplitters in our experiment). (c) SPP-based OAM demultiplexer. The received OAM beams are split into four copies by a 1 × 4 splitter (three beamsplitters), for each of which (ℓ) is demultiplexed and converted into a Gaussian beam by a reverse SPP of (−ℓ). (d) OAM mode demultiplexer. The received OAM beams are demultiplexed by an OAM mode demultiplexer, which can spatially separate the four OAM beams without power-splitting loss. Pol: polarization, MUX: multiplexing, DeMUX: demultiplexing, Ch: channel, BS: beamsplitter.
