All-fiber polarization-division multiplexing to mode-division multiplexing conversion for hybrid optical networks.

This paper proposes and experimentally demonstrates an all-fiber conversion method that transfers the polarization-division multiplexing (PDM) signals to the mode-division multiplexing (MDM) signals. The conversion scheme is based on a mode converter and a polarization-mode controller. The input X-polarized/Y-polarized fundamental modes are converted to the first-order linear-polarized LP11A/LP11B modes with crosstalk of -10 dB/-18 dB and insertion losses of 3.04 dB/3.1 dB at 1550 nm, respectively. Using the proposed converter, 11.2 GBaud/s polarization-division-multiplexed quadrature-phase-shift keying (PDM-QPSK) and 16 quadrature-amplitude-modulation (PDM-16QAM) signals are successfully converted to 11.2 GBaud/s MDM-QPSK and MDM-16QAM signals.