title: 110 km transmission of 160 Gbit/s RZ-DQPSK signals by midspan polarization-insensitive optical phase conjugation in a Ti:PPLN waveguide.
abstract: We demonstrate 160 Gbit/s return-to-zero (RZ) differential quarternary phase-shift keying (DQPSK) signal transmission over a 110 km single-mode fiber by taking advantage of mid-span optical phase conjugation (OPC). The technique is based on nonlinear wavelength conversion by cascaded second harmonic and difference frequency generation in a Ti:PPLN waveguide. Error-free operation with a negligible optical signal-to-noise ratio penalty for the signal after the OPC transmission without and with polarization scrambling was achieved. The results also show the polarization insensitivity of the OPC system using a polarization diversity scheme.
authors.affiliation: Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institut, Einsteinufer 37, 10587 Berlin, Germany. huhao@fotonik.dtu.dk
authors.forename: Hao
authors.initials: H
authors.lastname: Hu
authors.forename: Rahman
authors.initials: R
authors.lastname: Nouroozi
authors.forename: Reinhold
authors.initials: R
authors.lastname: Ludwig
authors.forename: Carsten
authors.initials: C
authors.lastname: Schmidt-Langhorst
authors.forename: Hubertus
authors.initials: H
authors.lastname: Suche
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Sohler
authors.forename: Colja
authors.initials: C
authors.lastname: Schubert