Excitation and measurement of laser induced wakefields

The amplitudes of wakefields excited by the ponderomotive force of an intense laser pulse are dependent on laser pulse shape and amplitude. Pulses with steep edges can drive wakefields in the standard LWFA when ωpΔτL>1. The temporal and spatial properties of the wakefield micro-structure can be measured by a single shot optical diagnostic based on frequency domain holography. In a proof of principle demonstration of this technique, cross-phase modulation of a weak probe pulse by two strong pump pulses is measured using the the nonlinear index of refraction of fused silica. copyright 1999 American Institute of Physics