Abstract

Fermi Pasta Ulam (FPU) recurrence process is a universal phenomenon that describes the natural return cycle of a nonlinear system into its initial state after experiencing a complex nonlinear coupling dynamics. In optical fibers it has been observed with reference to the nonlinear stage of modulation instability (MI) [1 , 2], which also plays a key role in supercontinuum and rogue wave formation. However, the nonlinear MI is characterized by a broken symmetry [3 , 4], which entails that, in a suitable phase-space, two qualitatively different types of evolutions can be followed by evolving from the modulated pump to a comb of sideband pairs and back to the pump. To date, the observation of such a broken symmetry has been elusive because of the intrinsic challenge of measuring the longitudinal evolution of the relative phase of the comb lines.

© 2017 IEEE