title: Copropagating superluminal and slow light manifested by electromagnetically assisted nonlinear optical processes.
abstract: We report an experimental observation of nonlinear optical gain and loss assisted by electromagnetically induced transparency (EIT) and simultaneous superluminal and subluminal light propagations. Two circular components of a linearly polarized light initiate third-order nonlinear processes in which one circular component is attenuated while the other component is amplified in a three-level EIT system. Near the atomic resonance, the attenuated circular component experiences steep normal dispersion and propagates with a slow group velocity, while the amplified circular component experiences steep anomalous dispersion and propagates with a superluminal group velocity.
authors.affiliation: Department of Physics, Florida International University, Miami, Florida 33199, USA.
authors.forename: Jiepeng
authors.initials: J
authors.lastname: Zhang
authors.forename: Gessler
authors.initials: G
authors.lastname: Hernandez
authors.forename: Yifu
authors.initials: Y
authors.lastname: Zhu