EFFECT OF REDISTRIBUTED RADIATION ON DEGENERATE 4-WAVE-MIXING

A model is formulated to investigate quantitatively how near-resonant degenerate four-wave mixing (DFWM) in a vapor of homogeneously broaden ed two-state atoms is affected by radiation scattered from the pump be ams. The spectral intensity distribution of the scattered radiation in the interaction volume is obtained -by solving the equation of radiat ive transfer and a detailed treatment of the modification this fluctua ting field causes on the optical dipole induced by the coherent laser fields is presented. For a broad parameter regime, this modification c an be expressed via a single quantity that incorporates the energy of the fluctuating field together with bandwidths and frequency offsets f rom the atomic resonance. Numerical solutions are given which show tha t the scattered field causes the DFWM reflectivity to be depressed by a significant amount, depending most strongly on a characteristic tran sverse length of the interaction volume. Approximate analytic expressi ons for the reflectivity are also given which assist in physically und erstanding the underlying mechanisms.