Journal of the Optical Society of America B
Cross-phase modulation caused by cascading of third-order processes
Solomon M. Saltiel, Kaloian Koynov, Krassimir Kirov, K. Petrova
Abstract
The evolution of the phase of a weak signal wave (ω2) copropagating with a strong gate wave (ω1) in a centrosymmetric medium is studied analytically and numerically for the case when the two waves are involved in a nearly phase-matched third-order process that generates a third wave (ω3=2ω1+ω2). It is shown that the signal wave collects, in addition to the phase shift that is due to the ω2=ω1+ω2-ω1 process, an extra nonlinear phase shift caused by cascading of two third-order nonlinear processes, ω3=2ω1+ω2 and ω2=ω3-2ω1. The attractive feature of this new type of cross-phase modulation is the fact that one can control its magnitude and sign by changing the wave-vector mismatch of the sum-frequency mixing process and the gate intensity.