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

摘要

A theoretical investigation on the quantum control of optical coherentfour-wave mixing interactions in two-level systems driven by two intensesynchronized femtosecond laser pulses of central angular frequencies $\omega$and $3\omega$ is reported. By numerically solving the full Maxwell-Blochequations beyond the slowly-varying envelope and rotating-wave approximationsin the time domain, the nonlinear coupling to the optical field at frequency$5\omega$ is found to depend critically on the initial relative phase $\phi$ ofthe two propagating pulses; the coupling is enhanced when the pulses interfereconstructively in the center ($\phi=0$), while it is nearly suppressed whenthey are out of phase ($\phi=\pi$). The tuning of the initial absolute phase ofthe different frequency components of synchronously propapagating$\omega$-$3\omega$ femtosecond pulses can serve as a means to control coherentanti-Stokes Raman scattering (CARS) processes.