We report controllable manipulation of slow and fast light in awhispering-gallery-mode (WGM) microtoroid resonator fabricated from Erbium(Er3+) doped silica. We observe continuous transition of the coupling betweenthe fiber-taper waveguide and the microresonator from undercoupling to criticalcoupling and then to overcoupling regimes by increasing the pump power eventhough the spatial distance between the resonator and the waveguide was keptfixed. This, in turn, enables switching from fast to slow light and vice versajust by increasing the optical gain. An enhancement of delay of two-fold overthe passive silica resonator (no optical gain) was observed in the slow lightregime. Moreover, we show dynamic pulse splitting and its control in slow/fastlight systems using optical gain.
展开▼
