Observation of delay enhancement in an ion-doped crystal.

We report the investigation of the reduction of the group velocity propagation resulting from the steep change of the refractive index by the coherent population oscillation in an erbium ion-doped optical fiber. We study fully the influences of the ion density and the temperature on the fractional and time delay. We find that the fractional delay can be decreased at high or low temperature. Moreover, we conclude that the temperature can be used as a control parameter to reduce distortion.