Characterization of coupled nonlinear spatiospectral phase following an ultrafast self-focusing interaction.

We use collinear spatially resolved spectral interferometery to characterize the nonlinear phase changes experienced by an intense ultrashort pulse propagating in glass. The measurement yields the spectrally dependent wavefront, allowing us to measure the spatial and chromatic aberrations of the nonlinearly induced lens. For these conditions, we find that while the shape of the spatial wavefront follows the beam profile as expected, the spectral dependence of the lensing power is determined by the self-phase modulation. The simultaneous measurement of the nonlinear spatiospectral phase demonstrates how the nonlinear spectral phase is coupled to self-focusing.