General compressor for ultrashort pulses with nonlinear chirp

A new type of grating compressor capable of compensating, in principle, for any arbitrary group-delay dispersion is described. The system relies on a specially designed grating with a variable groove spacing along its surface as well as a variable angle of incidence. In this manner each wavelength actually sees a different grating, always at Littrow incidence, that gives rise to distinct group delays. The design equations are derived, and the particular case of a cubic compressor is discussed. It is shown that, within practical limits, both quadratic and cubic terms can be simultaneously compensated for in typical optical fibers.