Simultaneous multilevel RZ-to-NRZ format conversion for two tributaries of a PDM signal

An all-optical multi-level RZ-to-NRZ format converter for two tributaries of a PDM signal is proposed using a polarization-maintaining-fiber inside a polarization-diversified-loop. A three-level format conversion in a 2×15.85-Gbit/s PDM system is experimentally demonstrated.