Mode‐selective coherent detection technique for low‐complexity mode division multiplexing systems

The mode division multiplexing (MDM) signal transmitted in an optical multimode fibre link is usually received with multiple coherent receivers (RXs), resulting in an increase in RX system scale. A mode‐selective coherent detection technique is proposed based on MDM‐to‐frequency division multiplexing (FDM) signal conversion scheme using an MDM and FDM local oscillator. The proposed technique uses only a single coherent RX to detect the MDM signal to achieve low‐complexity MDM systems. The proposed mode‐selective coherent detection technique is also experimentally shown. The experimental results show that a single coherent RX successfully receives the MDM signal.