Signal Evolution of Slow and Fast Light in Erbium Doped Fiber

Recently, researches about the controllable group velocity of light propagation had made many progresses. And several experiments had demonstrated the signal evolution of slow and fast light. In this letter, the authors described a simple experiment for the tracing of light signals in an erbium-doped optical fiber at the optical communication wavelength firstly. We have, directly, observed the evolution of slow and fast signals with different waveforms that travel in an erbium-doped fiber amplifier. Through tracing the signal evolution, when slow light (Vg<;<;c) or fast light (Vg<;0) was got in it, we concluded that asymmetrical absorption and amplification on the periodical signal could account for the generation of slow and fast light in an erbium-doped fiber amplifier easily.