Third-order optical mixing of frequencies of a strong bichromatic field interacting with a three-level atom in the “Lambda” configuration

Abstract

We have considered the excitation spectra of three-photon processes arising from the interaction of a three-level atom, in the “lambda” configuration, with two strong electromagnetic fields whose initially populated modes ω a and ω b are at resonance with the two atomic transition frequencies, respectively. In the limit of high photon densities, expressions for the spectral functions are derived describing third-order nonlinear processes near the frequencies ω = ± (ω a − 2ω b) and ω = ± (ω b − 2ω a), respectively. Analytical calculations are then performed and the computed spectra are presented graphically for different values of the Rabi frequencies Ω a and Ω b, respectively. Expressions for the spectral function near the frequence ω = ω a − 2ω b are derived for specific values ω ⪡ η b, η b ≈ 2η a, η a ≈ η b, η a ≈ 2η a and η a ⪢ η b, where η a = Ω a/γ 0 and η b = Ω b/γ 0 are the reduced Rabi frquencies of the laser fields, respectively, and γ 0 is the s pontaneous emission probability. The computed spectra are compared with the corresponding ones for an atom in the “V” configuration.