: Hu, H.; Nouroozi, R.; Ludwig, R.; Huttl, B.; Schmidt-Langhorst, C.; Suche, H.; Sohler, W.; Schubert, C.

Abstract
Simultaneous all-optical wavelength conversion of an 80-Gb/s return-to-zero differential quadrature phase shift keying (RZ-DQPSK) data signal and a 40-Gb/s return-to-zero ON--OFF keying (RZ-OOK) data signal using a Ti:PPLN waveguide in a polarization-diversity loop configuration are demonstrated. The wavelength conversion is fully transparent to polarization, data rate, modulation format, and modulation level. The conversion efficiency for the signals was -21 dB, which includes 9.2-dB passive losses in the whole Ti: PPLN subsystem. Error-free performance for both wavelength-converted signals was achieved for polarization-scrambled input data signals without additional penalty caused by the polarization scrambling.