25.6-bit/s/Hz spectral efficiency using 16-QAM signals over pol-muxed multiple orbital-angular-momentum modes

We demonstrate generation/multiplexing/demultiplexing of polarization-multiplexed (pol-muxed) multiple orbital-angular-momentum (OAM) modes. High spectral efficiency of 25.6-bit/s/Hz is implemented using 10.7-Gbaud 16-QAM signals over pol-muxed four OAM modes. An OSNR penalty less than 3.5 dB is observed.