Abstract

The refractive index change (RIC) of the pumped rare-earth-doped optical fibers is caused by a population change of levels with a different polarizability [1-3]. The origin of the polarizability difference (PD) is widely discussed during recent years. Some authors believe that the main contribution to the PD comes from near-resonance IR transitions, rather than far-from-resonance strong UV transitions [1, 3]. The understanding of the phenomenon appears to be very important because the pump-induced index change could be used for optical switching and coherent beam combining [2]. Besides, the enhanced nonlinear phase shift could significantly impact dynamics of fiber lasers and amplifiers.

© 2007 IEEE