Abstract

The availability of an accurate value of the Kerr nonlinear in-dex, n₂ of the optical fibers used in the transmission lines is an important issue. The measurement of n₂ is actually obtained by the evaluation of the Kerr-induced phase shift in self,¹ or cross-² phase-modulation schemes. Unfortunately, the n₂ value recovered by these methods contains an uncertainty due to the polarization parameter b and n₂ is accurately evaluated only when probe and pump (or pump alone in the self technique) propagate on the main axis of a polarization-holding fiber. The common optical fibers present stress-induced birefringence, which perturbs the state of polarization (SOP) of the guided light, hence affecting the measurement of n₂. In particular, in the cross-phase-modulation scheme, the polarization parameter b assumes values oscillating between "1" and "1 /3" (pump and probe with parallel and orthogonal polarization respectively).²

© 1996 Optical Society of America