Fourth-order dispersion compensation for ultra-high power femtosecond lasers

Fourier-transform-limit pulses are required by recent petawatt-class femtosecond chirped-pulse amplification lasers for increasing peak powers, but which are challenged by the residuals of the high orders of dispersion, for example the fourth-order dispersion. We propose a stable and economy passive dispersion compensation method to completely cancel out the static second-, third- and especially fourth-order dispersion by inserting a grism pair into the standard chirped-pulse amplification system between the stretcher and the compressor. The best dispersion compensation condition would be achieved by optimizing both the grism pair and the compressor. Compared with the recent passive dispersion compensation method, the experiment results show the pulse duration could be further reduced from 35 fs to 28 fs, the peak intensity of the compression pulse could be increased by 1.25 times, and the spectral phase distortion over the pulse spectrum could be reduced from 12 rad to 4 rad.