Measurement of transient nonlinear refractive index in gases using xenon supercontinuum single-shot spectral interferometry

A highly stable version of spectral interferometry is demonstrated, allowing single shot measurement of ultrafast high field processes using modest energy lasers, with pump and probe pulses totaling less than 1 mJ. The technique makes possible reconstruction of ultrafast refractive index transients with one- dimensional spatial resolution, limited only by the bandwidth of the supercontinuum pulse (similar to 100 nm) and instrument resolution. The ultrafast nonlinear Kerr effect in glass, and in Ar, N-2, and N2O gases is measured, along with plasma generation in Ar. The inertial contribution to the nonlinear index from N-2 and N2O molecular rotation is also observed. (C) 2007 Optical Society of America.