All-optical regeneration of polarization of a 40 Gbit/s return-to-zero telecommunication signal[Invited]

We report all-optical regeneration of the state of polarization of a 40 Gbit∕s return-to-zero telecommunication signal.The device discussed here consists of a 6.2-km-long nonzero dispersion-shifted fiber,with low polarization mode dispersion,pumped from the output end by a backward propagating wave coming from either an external continuous source or a reflection of the signal.An initially scrambled signal acquires a degree of polarization close to 100%toward the polarization generator output.All-optical regeneration is confirmed by means of polarization and bit-error-rate measurements as well as real-time observation of the eye diagrams.We show that the physical mechanism underlying the observed four-wave-mixing-based polarization attraction phenomenon can be described in terms of the geometric approach developed for the study of Hamiltonian singularities.