High-energy pulse compressor using self-defocusing spectral broadening in anomalously dispersive media

A method and a pulse compressor (1) for compressing an optical pulse, wherein the pulse compressor comprising a bulk quadratic nonlinear medium (2) adapted for generating a negative nonlinear phase variation on the optical pulse and having a negative group-velocity dispersion, and a dispersive unit (3) with a net positive dispersion. Furthermore, the net positive dispersion in the dispersive unit at least partially compensates for the negative nonlinear phase variation and the negative group-velocity dispersion produced by the bulk quadratic nonlinear medium when the optical pulse passes through the bulk quadratic nonlinear medium and subsequently through the dispersive unit thereby generating a temporally compressed optical pulse. For 1 micron lasers second-harmonic generation at high intensities yields spectral broadening due to self-defocusing by the Kerr-nonlinearity which can subsequently be compressed by providing normal dispersion. As KDP crystals can be glued together, large apertures of the pulse compressor are possible making this method suitable for pulse compression in Joule-class lasers.