  The generation of broadband supercontinua (SC) in air-silica microstructured
fibers results from a delicate balance of dispersion and nonlinearity. We
analyze two models aimed at better understanding SC. In the first one, we
characterize linear dispersion in the Fourier domain from the calculated group
velocity dispersion (GVD) without using a Taylor approximation for the
propagation constant. Results of our numerical simulations are in a good
agreement with experiments. A novel relevant length scale, namely the length
for shock formation is introduced and its role is discussed. The second part
shows similar dynamics for a model that goes beyond the slowly varying
approximation for optical pulse propagation.
