Abstract

A recently presented treatment of four-wave mixing for fields of arbitrary strength¹ is applied to the 3S–3P transitions of sodium. The line shapes associated with ordinary resonances, and with both pressure-induced and field-induced extra resonances are investigated. In sodium, the two lower levels (g,t) are very close, i.e., their separation is 0.059 cm^-1. Thus decays from the upper (k,j) levels to each of the lower levels are expected to contribute significantly. Also, contributions associated with (g,t) population exchange because of the close proximity of these states are incorporated. The influence of the decay pattern and of the respective values of the decay constants is studied, especially as compared to the line shapes that would result if all decays were dominantly to the ground state. Regions of enhancement for the more complex decay pattern are found for field-induced extra resonances. The relative effects of spontaneous decay (T₁) and proper dephasing (T₂) on the line shapes is examined. It is found that (T₂) dominates for weak field conditions but that both contribute significantly for strong field situations.

© 1991 Optical Society of America