Coherent Population Trapping

Coherent trapping in three level lambda and ladder systems is examined for the case of two fluctuating laser fields with unequal bandwidths, obtained by frequency multiplying methods. The inclusion of uncorrelated laser fields destroys trapping and washes out the narrow coherence hole in the fluorescent intensity. However, if the fields are positively critically cross-correlated, the relevant atomic coherences in lambda systems are much less affected by the laser fluctuations. A significant degree of trapping re-occurs and the narrow coherence hole is largely restored. An enhancement of the destruction of coherent trapping occurs in ladder systems. An application of the theory to molecular photodissociation is discussed.