ABSTRACT
The invention of conventional lasers [1] with their unique property to deliver intense monochromatic and coherent photon beams has had a dramatic impact on many scientific and technological domains. Current research in physics, chemistry, and biology is based, to a large extent, on the application of laser systems with extremely high spectral resolution (operating in continuous wave mode) or with high pulse energies and/or ultrashort duration in pulsed mode. However, the wavelength regime of conventional lasers is limited to the infrared and visible spectral ranges since the reflectivity of mirrors (needed for the optical cavity) drops drastically at very short wavelengths. Hence the main photon sources for extreme-UV (EUV) and x-ray radiation are generally synchrotron radiation facilities based on large electron storage rings [2]. The latest (third) generation synchrotron sources are very powerful tools
Ion
for studying processes induced by the interaction of short-wavelength light with strongly bound inner-shell electrons and for unraveling the complex structure of solids or biomolecules in diffraction experiments. However, synchrotron radiation is produced by the emission of electron bunches circulating at relativistic velocities in the storage rings, and therefore the pulse duration is generally limited to several picoseconds and the pulse energies reside typically in the nanoJoule regime. It is against this background that a substantial research effort to develop intense EUV photon sources with laser-like properties, opening up exciting new research fields, has been undertaken during the past two decades.
