" Instability limits to "fast light" pulse propagation"
Daniel Gauthier, Michael Stenner (Duke University, Department
of Physics, Box 90305, Durham, NC 27708)
Using intense electromagnetic fields, it is now possible to tailor the
absorption, amplification, and dispersion
properties of multi-level atoms. Dramatic examples include the reduction
of the group velocity of a pulse of
light to a few meters per second ("slow light"), and increasing the
group velocity to values greater than the
speed of light in vacuum or even to negative values ("fast light").
A recent technique for creating fast light
involves pulse propagation in the vicinity of a gain doublet arising
from Raman scattering in laser-driven
rubidium atoms. We observe that the Raman-pump field is unstable upon
propagation through the vapor,
limiting the attainable fast light effect. The Raman pump beam undergoes
a fantastic spectral broadening and
collapse to a train of ultrashort pulses. We will describe our observations
and discuss the implications of our
results on fast light pulse propagation.
Last Modified: 28-Mar-02