Response of grating pairs to single-cycle electromagnetic pulses

The chirp of single-cycle microwave fields after interaction with pairs of parallel diffraction gratings is measured in a phase-sensitive terahertz spectrometer. Novel transmission grating pairs recently proposed by Tournois, which combine diffraction and refraction effects, yield an almost linear group delay over a bandwidth that exceeds that of conventional reflection gratings by a factor of ,3.5. The experimentally measured group delay shows good agreement with theoretical predictions for both types of grating. The applicability of the novel transmission gratings for stretching and compression of 1–2-fs pulses in the optical regime and the limitations set by material dispersion are discussed.