Spatial beam shaping of ultrashort laser pulses: theory and experiment

摘要

We studied the spatial intensity profile of an ultrashort laser pulse passing through a laser beam shaping system, which uses diffractive optical elements to reshape a Gaussian beam profile into a flat-topped distribution. Both dispersion and nonlinear self-phase modulation are included in the theoretical model. Our calculation shows that this system works well for ultrashort pulses (similar to 100 fs) when the pulse peak intensity is less than 5 X 10(11) W/cm(2). Experimental results are presented for 136 fs pulses at 800 nm wavelength from a Ti:sapphire laser with a 6 nJ pulse energy. We also studied the effects of lateral misalignment, beam-size deviation, and defocusing on the energy fluence profile. (c) 2005 Optical Society of America.