Optics Letters
Modulation-frequency-controlled change from sub- to superluminal regime in highly doped erbium fibers
Sonia Melle, Óscar G. Calderón, E. Cesar, E. Cabrera, M. A. Antón, F. Carreño
Abstract
We report a change from sub- to superluminal propagation upon increasing the modulation frequency of an amplitude-modulated 1,550 nm signal when propagating through highly doped erbium fibers pumped at 980 nm. We show that the interplay between the pump absorption and the pump-power broadening of the spectral hole induced by coherent population oscillations may drastically affect the fractional advancement or delay of the signal for the considered fibers.