Diffraction Gratings for the Selection of Ultrashort Pulses in the Extreme-Ultraviolet

Abstract

We discuss the use of diffraction gratings to perform the spectral selection of ultrashort pulses in the extreme-ultraviolet and soft X-ray spectral regions, ranging in the 3-100 nm wavelength range. The main application of such a technique is the spectral selection of highorder laser harmonics and free-electron-laser pulses in the femtosecond time scale. We present the design and realization of both single- and double-grating monochromators using an innovative grating geometry, namely the off-plane mount. The performances of existing instruments are shown. The use of diffraction gratings to change the phase properties of the pulse, e.g. to compress it to shorter temporal duration close to the Fourier limit, is also discussed. Extreme-ultraviolet (XUV) and X-ray photons have been used for many fundamental discoveries and outstanding applications in natural sciences (Wiedermann, 2005). They have