Two-dimensional nonlinear optics using Fourier-transform spectral interferometry.

The second-order nonlinear-optical response of a material is measured in two dimensions of frequency. This new spectroscopy technique, based on the use of Fourier-transform spectral interferometry, is a transposition to optics of two-dimensional nuclear magnetic resonance. Although we demonstrate the technique by measuring the second-order phase-matching map of a nonresonant nonlinear crystal, this method should find useful applications in the measurement of second-order nonlinear susceptibility and in photon-echo experiments.