Ultra-high bandwidth efficiency implementation based on polar coded symbol division multiplexing in short-reach optical interconnection

A symbol division multiplexing (SDM) scheme based on joint coded modulation is proposed and experimentally demonstrated in an optical discrete multi-tone (DMT) quadrature amplitude modulation (QAM) interconnection. By polar coded four-to-one mapping per constellation, the SDM-8QAM achieves ultra-high 66.7 % expansion in QAM symbol capacity as well as bandwidth efficiency at the same baud rate. An iterative mechanism between QAM demapping and polar decoding is proposed to address SDM demultiplexing (De-SDM) with ambiguous symbol decision. The experimental results show that the proposed SDM scheme obtains a receiver power sensitivity improvement by 1.28 dB compared with conventional distributed QAM over 10-km standard single-mode fiber transmission.