  Ultralong trapping of light has been observed in an optically dense
three-level solid medium interacting with a pair of counterpropagating coupling
fields. Unlike the light trapping based on standing-wave gratings excited by
the same frequency pair of counterpropagating light fields (M. Bajcsy et al.,
Nature 426, 638 (2003)), the present method uses resonant Raman optical
field-excited spin coherence gratings. The observed light trapping time is two
orders of magnitude longer than the expected value of the spin dephasing time,
where the extended storage time has potential for quantum information
processing based on nonlinear optics.
