Effects of initial focusing on the blueshifting of high-power laser pulses

摘要

By directly solving Maxwell's equations including higher-order gas polarization and by using a semi-analytical method for pulse propagation, we study the generation of plasma by high-irradiance laser pulses propagating in a neutral gas and determine the effect of initial focusing on the blueshift of the laser pulse. By varying the initial focusing length, we find that longer than a specific focusing length the blueshift is nearly fixed and shorter than the specific focusing length that the shift changes with the initial focusing length.