Noncollinear third-harmonic Maker fringes for the determination of third-order nonlinear optical susceptibilities

We describe noncollinear third-harmonic Maker fringes for the determination of third-order optical nonlinearities. This method builds on the same principles as conventional Maker fringes experiments, but thanks to the limited interaction length of two intersecting beams, it allows to eliminate the requirement of taking into account the contribution of air to the third-harmonic signal. Thus, third-order susceptibilities can be accurately determined without the need for a vacuum chamber. We review the theoretical underpinnings of the method, and discuss the dependence of the coherence length for harmonic generation on the intersection angle between the beams and the sample orientation, and the effect this has on the Maker fringes pattern.