Study of dispersions on grating-pair compressor in the case of unparallel grooves

In this paper, we analyze the diffraction characteristics of grating-pair compressor in a chirped-pulse amplification (CPA) laser system, under the conditions that the grating surfaces are parallel while the grating grooves are unparallel. The optical path length of pulse passing through this system is derived. Then the second-, third- and fourth-order dispersions are calculated. The resulting dispersion relative errors compared with that the grating grooves, which are strictly parallel are shown. The vertical spectrum displacement in the output pulse has been calculated and shown quantitatively as function of the angle between the grooves. The results also show that gratings with low groove density are superior to that of high density ones, if the groove misalignment is unavoidable.