Resonances of the six-wave mixing susceptibility χ<sup>(5)</sup>(ω<sub>1</sub>, ω<sub>1</sub>, ω<sub>1</sub>, −ω<sub>2</sub>, −ω<sub>2</sub>) at frequency 3ω<sub>1</sub>−2ω<sub>2</sub> of a system of two-level atoms dissipating through the spontaneous emission and collisions and driven by a weak bichromatic external field of frequencies ω<sub>1</sub> and ω<sub>2</sub> in a finite <i>Q</i> cavity are analyzed. It is shown that the atomic collisions not only induce the usual Bloembergen resonances but that they also play a major role in enhancing the transitions among the higher-order dressed states, thereby bringing out some of the quantum resonances that are suppressed in the absence of collisions. The important contribution of collisions in this higher-order nonlinear process is the generation of the subharmonic resonances at ±1/2 times the hyperfine splitting of the first and the second excited manifolds.
© 2000 Optical Society of America
(190.0190) Nonlinear optics : Nonlinear optics
Aditi Ray and R. R. Puri, "Resonances in the collision-induced spectrum of six-wave mixing susceptibility: generation of subharmonics," J. Opt. Soc. Am. B 17, 1704-1710 (2000)