Physical Review A
Slow and fast light via two-wave mixing in erbium-doped fibers with saturable absorption
Serguei I. Stepanov, Marcos Plata Sánchez
Abstract
We report experimental observation of slow or fast light in configuration of counterpropagating saturating and probe waves in erbium-doped fibers with saturable absorption. The delayed or accelerated probe light propagation is shown to be associated with two-wave mixing (TWM) between these two waves via dynamic population grating. As compared with recording at 1526 nm from the central region of ${\text{Er}}^{3+}$ fundamental absorption spectrum, at 1485 nm, the population grating has significant admixture of the refractive index component. This results in a significant asymmetry of the TWM-induced transmittance of the probe wave as a function of the frequency offset $\ensuremath{\Delta}\ensuremath{\Omega}$ between the waves and shifts position of the maximum group delay from zero $\ensuremath{\Delta}\ensuremath{\Omega}$. The same reason ensures appearance of a significant group advancement for the frequency offset of the opposite sign.