ENHANCEMENT OF DEGENERATE 4-WAVE-MIXING BY ATOM-WALL COLLISIONS IN ATOMIC VAPORS

Resonant cw degenerate four-wave mixing signals usually are not observed at noncycling transitions in alkali-metal vapors due to population depletion from optical pumping. We demonstrate that frequent atom-wall collisions can overcome the effects of optical pumping when atomic vapors are contained in thin cells. Significantly enhanced degenerate four-wave mixing signals are observed at noncycling transitions, and they are comparable in magnitude to the signals observed at cycling transitions in thin cells. This technique extends the utilization of degenerate four-wave mixing to noncycling transitions in atoms or molecules.