Nonlinear polarization effects

In the present work we study both experimentally and theoretically in optical fiber systems, the four-wave interactions between the polarization states of a pump wave and of a counter-propagating signal wave. In particular we report a novel phenomenon of attraction characterized by the evolution of the signal wave towards a well determined polarization state that is independent of the initial polarization state of the signal wave. We show that this fascinating attraction process appears with temporally coherent waves, and also remarkably, with temporally incoherent waves. We also illustrate the polarization attraction process in the case of an isotropic fiber for different degrees of temporal coherence of the pump and signal waves. Finally, we discuss applications of the polarization attraction process for optical transmission and signal processing systems.