Nonperturbative analysis of four-wave mixing in a four-level system with three strong fields

Radiative renormalization is used to obtain an exact steady-state solution of a four-level system coupled by three arbitrarily strong, near-resonant, monochromatic fields. The four-wave mixing and absorption terms are given for a weak fourth field. The results demonstrate the effects of optically induced energy-level mixing and shifting, and population redistribution. © 1996 The American Physical Society.