Hoonsoo Kang

Backward four-wave mixing in a four-level medium with electromagnetically induced transparency

We analyze backward four-wave mixing in a four-level system exhibiting electromagnetically induced transparency (EIT). We show that EIT suppression of the linear absorption leads to the resonantly enhanced four-wave mixing process and the conversion efficiency near 100% may be achieved in a dense four-level medium with negligible decoherence decay.

Nonlinear wave mixing with electromagnetically induced transparency in cold atoms

Electromagnetically induced transparency (EIT) in a four-level atomic system suppresses linear absorption and leads to resonantly enhanced slow-light four-wave mixing at low light intensities. We analyse the backward four-wave mixing in the four-level system under the EIT conditions, derive the four-wave-mixing efficiency and discuss slow-light propagation conditions. We present experimental measurements of resonant four-wave mixing with the backward scheme in cold Rb atoms and compare the experimental results with the theoretical calculations.

Observation of Three-photon and One-photon Interference in A Double EIT System

We report an observation of destructive interference between three-photon and one-photon excitations in a four-level atomic system, which leads to electromagnetically induced transparency and slow group velocities simultaneously for two probe fields.

Slow-light four-wave mixing at low light intensities

We report an experimental study of slow light diffraction from a resonant nonlinear grating in cold Rb atoms. Alternatively, the diffracted light can be viewed as generated from an EIT enhanced six-wave mixing process