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

Resonant cw degenerate four-wave mixing signals usually are not observ ed 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 va pors are contained in thin cells. Significantly enhanced degenerate fo ur-wave mixing signals are observed at noncycling transitions, and the y are comparable in magnitude to the signals observed at cycling trans itions in thin cells. This technique extends the utilization of degene rate four-wave mixing to noncycling transitions in atoms or molecules.