Ultrafast atomic phase modulation

We demonstrate a phenomenon very similar to electromagnetically induced transparency using a shaped ultrafast laser pulse. Pulse shaping allows us to produce probe and coupling pulses with arbitrary intensities and time delays. The coupling Rabi frequency and probe bandwidth are both on the order of 1 THz, which is much larger than the natural or Doppler broadened linewidth of the probe transition. Important dynamics associated with a time-dependent coupling field are discussed.