Abstract

For about 15 years, the atomic physics community has been aware of a phenomenon which is termed as population trapping.^[1,2] When two lasers with frequencies which couple two lower states of an atom to a common upper state, or to a common continuum, are applied to an atom, the population is frozen or trapped in the lower states. The common upper state is empty, and the contribution of the atom to the steady state linear susceptibility is zero. During this past year it has been shown that this effect can be used to greatly increase the transparency of an otherwise opaque media. Working on an autoionizing transition at 337 nm in neutral Sr, K.-J. Boiler et al^[3] applied a 570 nm laser beam and changed the transmission at 337 nm from exp(-20) to exp(–1). Field et al^[4] showed that these effects may also be present in pressure broadened systems, and used a 1064 nm laser to increase the transmission on the 283 nm resonance line of Pb from less than exp(–14) to exp(–4).

© 1992 IQEC