Controllable group velocity of light pulse in erbium-doped optical fiber at room temperature

In the absorption spectrum of the medium a burning hole appeared by coherent population oscillation, and the linewidth of this feature was approximately the inverse of the ground state population recovery time. Based on the theoretical analysis of gain the effect of absorption was different for different pump power. In a medium with absorption the oscillation leads to the pulse experiencing absorption saturation and propagation delay; in a medium with gain this effect induces the pulse experiencing gain saturation and propagation advance. Making use of coherent population oscillation we controlled the group velocity of light propagation in erbium-doped optical fiber. In experiment, the slowest group velocity was 2.857 x 10(3) m/s, and the corresponding group index was 10.5 x 10(4). According to coherent population oscillation and gain, we obtained the analytic expression of the group delay from rate equation and its simulation results were quantitatively coincident with our experimental data. The methods of controlling group velocity were comprehensively analyzed through the analytic model.