Five‐wave mixing ω b = ω 1 + ω 1 + ω 1 − ω 2 in the bulk of a chiral liquid

We propose a theory of wave generation at a frequency ω b in the bulk of an isotropic gyrotropic medium by two non‐collinear Gaussian beams of fundamental radiation with the frequencies ω 1,2 . The calculations are made with allowance for linear optical rotation of the medium in the case where the dimensions of the efficient‐generation volume are much smaller than the diffraction lengths of the intersecting beams. Analytical expressions for the spatial distribution of the field and the total power of a signal wave at the frequency ω b were obtained. The spatial dispersion of the optical response of the medium is found to have a distinct effect on the shape of the phase‐synchronism curves, and to lead to the signal wave becoming elliptically polarized even under linear polarization of the fundamental waves. It was revealed that the dependence of the signal power on the polarization states of the fundamental waves changes substantially when the optical rotatory power of the medium increases. On the basis of the experimental data available, an estimation was made of the magnitude of the fourth‐order non‐linear optical susceptibility in the specific case of second harmonic generation in an aqueous arabinose solution. Copyright © 2000 John Wiley & Sons, Ltd.