Controllable ultraslow light propagation in highly-doped erbium fiber

We report on slow light propagation induced by the coherent population oscillation in an erbium-doped optical fiber (EDOF). The slowdown of group velocity of light is demonstrated in a solid-state material at room temperature. We observe a maximum fractional delay of 0.129 and a maximum delay of 8.75 ms corresponding to a group velocity as low as 228.57 m/s in a sinusoid-like modulated waveform. We study in details the influences of the erbium ion density and the length of fiber on the fractional delay and the slow light propagation. The data show that the fractional delay can be increased using the fiber with high erbium ions density or long interaction length.