110 km transmission of 160 Gbit/s RZ-DQPSK signals by midspan polarization-insensitive optical phase conjugation in a Ti:PPLN waveguide.

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.

Phase control of double-pass cascaded SHG/DFG wavelength conversion in Ti:PPLN channel waveguides.

The efficiency of wavelength conversion by cascaded second harmonic generation / difference frequency generation (cSHG/DFG) in Ti:PPLN waveguides can be considerably improved by using a double-pass configuration. However, due to the wavelength dependent phase change by the dielectric folding mirror phase compensation is required to maintain an optimum power transfer. We experimentally investigated three different approaches and improved the wavelength conversion efficiency up to 9 dB in comparison with the single-pass configuration.

Wavelength selective single and dual-channel dropping in a periodically poled Ti:LiNbO(3) waveguide.

All-optical wavelength selective single and dual channel dropping by sum frequency generation has been demonstrated in a periodically poled Ti:LiNbO(3) waveguide, which has two second harmonic phase-matching peaks. Less than -17 dB of channel dropping extinction ratio was observed with coupled pump power of 325 mW.

Distributed feedback-distributed Bragg reflector coupled cavity laser with a Ti:(Fe:)Er:LiNbO3 waveguide.

A thermally fixed photorefractive Bragg grating is written in a single-mode Ti:Fe:Er:LiNbO3 channel waveguide and used to develop a distributed feedback-distributed Bragg reflector coupled cavity laser with a second broadband dielectric cavity mirror. The optically pumped (lambda(p) = 1480 nm, P = 130 mW) laser emits in single-frequency operation as much as 8 mW at lambda = 1557.2 nm with a slope efficiency of approximately 22%.