Spatial profile distortion of harmonically-converted partially-coherent light

Incoherent Light techniques (ISI and PCL) have been proposed to achieve the high degree of spatial beam uniformity required in the foot pulse of a laser fusion driver. Although these techniques provide outstanding beam smoothing performance in KrF lasers, their use in glass lasers appears to be limited by nonlinear optical effects. The simulations presented in this paper show that the harmonic conversion process can introduce distortion of the time-averaged focal profile, and this distortion is exacerbated by even the modest amount of self phase modulation likely to be generated in the low intensity foot pulse.