Coherent control of optical four-wave mixing by two-color $ω$-$3ω$ ultrashort laser pulses

Abstract

A theoretical investigation on the quantum control of optical coherent four-wave mixing interactions in two-level systems driven by two intense synchronized femtosecond laser pulses of central angular frequencies $ω$ and $3ω$ is reported. By numerically solving the full Maxwell-Bloch equations beyond the slowly-varying envelope and rotating-wave approximations in the time domain, the nonlinear coupling to the optical field at frequency $5ω$ is found to depend critically on the initial relative phase $ϕ$ of the two propagating pulses; the coupling is enhanced when the pulses interfere constructively in the center ($ϕ=0$), while it is nearly suppressed when they are out of phase ($ϕ=π$). The tuning of the initial absolute phase of the different frequency components of synchronously propapagating $ω$-$3ω$ femtosecond pulses can serve as a means to control coherent anti-Stokes Raman scattering (CARS) processes.