Phasefront preservation in high-gain Raman amplification

Experiments were performed to determine the degree of phasefront preservation possible in a high-gain, large-Fresnel-number number Raman amplifier. Phasefront information was encoded on a Stokes seed, which was then amplified in a 10-atm vibrational hydrogen Raman amplifier pumped by a XeF excimer laser. Interferometric data on the input and amplified Stokes beam indicate that their phasefront difference is less than 0.1 wave RMS. These results are consistent with the predictions of a numerical model of the Raman amplification process.>