Polarization-insensitive all-optical wavelength conversion of 320 Gb/s RZ-DQPSK signals using a Ti:PPLN waveguide

Polarization-insensitive wavelength conversion of a single channel 320 Gb/s RZ-DQPSK data signal using a Ti:PPLN waveguide in a bi-directional loop configuration with less than 0.5 dB polarization sensitivity is reported. The conversion efficiency with polarization scrambling of the signal was -21 dB, which includes 9.2 dB of passive losses in the whole Ti:PPLN subsystem. In BER measurements error-free operation with 2 dB OSNR penalty for the converted signal was achieved. Theoretical and experimental investigations of the temporal shape and chirp of the converted data pulses show only very little broadening and chirping, indicating the potential for wavelength conversion of even much higher data rates.