Coherent Control and Nonlinear Wave Mixing in Slow Light Media

Eugeny Korsunsky

Jacob B. Khurgin, R.S. Tucker

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 The propagation of light in dispersive media can be described by five different kinds of wave velocities [1-3]: • Phase velocity, which is the speed at which the zero crossings of the carrier wave move • Group velocity, at which the peak of a wave packet moves • Energy velocity, at which the energy is transported by the wave • Signal velocity, at which the half-maximum wave amplitude moves • Front velocity, at which the first appearance of a discontinuity moves Generally, all five velocities can differ from each other, although in a linear passive dispersive media, they coincide and are, usually, less than the light velocity in vacuum. Recently, experimental demonstrations [4-6] in variousmedia show that the group velocity of light canbe reducedby10-100million compared with its vacuum phase velocity. The physics is based on very steep frequency dispersion in the vicinity of narrow resonance of electromagnetically induced transparency (EIT) [7-11].

U. Bortolozzo, S. Residori, Jean‐Pierre Huignard

Slow-light is obtained through nonlinear wave-mixing in a liquid crystal light-valve. A deceleration of light pulses down to group velocities as small as 0.2 mm/s is achieved when two-wave-mixing is performed with a continuous pump and a time modulated signal. A model accounts for the observations in the general framework of nonlinear wave-mixing in thin media. The large group delay provided by the light-valve is exploited to enhance the spectral sensitivity of an interferometer, whereas the narrow frequency bandwidth of the two-wave-mixing gain is used to realize an adaptive holographic system that allows achieving subpicometer detection.

A. A. Zobolotskii

Pochi Yeh

A. M. Akulshin, Russell McLean

Atomic media have played a major role in studies of fast light. One of their attractive features is the ability to manipulate experimental parameters to control the dispersive properties that determine the group velocity of a propagating light pulse. We give an overview of the experimental methods, based on both linear and nonlinear atom-light interaction, that have produced superluminal propagation in atomic media, and discuss some of the significant theoretical contributions to the issues of pulse preservation and reconciling faster-than-light propagation and the principle of causality. The comparison of storage of light, enhanced Kerr nonlinearity and efficient wave mixing processes in slow and fast light atomic media illustrates their common and distinct features.