Near-field imaging of nonlinear pulse propagation in planar silica waveguides.

A simplified near-field scanning optical microscope is employed to image the propagation of short laser pulses in planar silica waveguides, in the anomalous dispersion regime, under varying conditions of input beam power and width. Our results show a complex evolution of the transverse intensity profiles of the beam when there is a pronounced difference between the input diffraction and dispersion lengths. Numerical simulations confirm that these complex spatial dynamics are intimately related to the temporal and spectral evolution of the pulse.