Frequency Upshifting of Laser Pulses by Ionization Fronts

摘要

A novel method for upshifting the frequency of a laser pulse is examined, whichutilizes the interaction of the pulse with a co=propagating relativistic ionization front. The induced frequency shift is found to initially scale linearly with the propagation time tau. Asymptotically, the frequency scales as sq. rt. tau. Phase slippage limitations may be overcome by appropriately increasing the plasma density as a function of tau, thus allowing for substantially higher frequency shifts.