Nonlinear spectral symmetry breaking of Light Bullets in waveguide arrays

We investigate the impact of the wavelength dependence of the discrete diffraction on the dynamics of Light Bullets (LBs) in a periodic medium. This dependence gives rise to a strong spatiotemporal coupling, which in turn leads to a spatiotemporally modified LB spectrum. This nonlinear spectral reshaping is measured and analyzed. It is found numerically and in experiment that it can be used to measure the strength of spatiotemporal coupling.