Melle Hernández, SoniaGómez Calderón, ÓscarCaro, César E.Cabrera Granado, EduardoAntón Revilla, Miguel ÁngelCarreño Sánchez, Fernando2023-06-202023-06-202008-04-150146-959210.1364/OL.33.000827https://hdl.handle.net/20.500.14352/52222Received December 11, 2007; revised March 4, 2008; accepted March 6, 2008; posted March 14, 2008 (Doc. ID 90388); published April 11, 2008We report a change from sub- to superluminal propagation upon increasing the modulation frequency of an amplitude-modulated 1550 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.engjournal articlehttps://doi.org/10.1364/OL.33.000827https://www.osapublishing.org/ol/abstract.cfm?uri=ol-33-8-827#Abstractrestricted access535.57621.391.6FiberserbiumNonlinear opticsFrequencyDoped erbium fibersSuperluminal regimeModulationÓptica (Física)Fibras y comunicación ópticaÓptica no líneal2209.19 Óptica Física2209.5 Fibras ópticas2209.13 Óptica no lineal