Modifying the optical path in a nonlinear double-slit experiment

In this Letter, we study a nonlinear interferometric setup based on diffraction, rather than beam combining. It consists of a nonlinear analog of Young's double-slit experiment where a nonlinear material is placed exactly after one of the slits. The presence of nonlinearity breaks the transverse spatial symmetry of the system and, thus, modifies the optical path. For moderate nonlinearities, this leads to a self-induced shift of the intensity pattern in the transverse plane. A simple theoretical model is developed which is surprisingly accurate in predicting the intensity profile of the main lobes for a wide range of parameters. We discuss possible applications of our model in nonlinear interferometry, for example in measuring the nonlinearities of optical materials.