Saturated amplification of fs laser driven collisional soft X-ray lasers

Obtaining a reliable XUV laser operating in an optical field ionization scheme has long been sought by numerous groups, both in recombination and collisional schemes. We report a successful observation of lasing in Pd-like xenon at 41.8 nm. High photon flux is obtained with respect to what can be expected in that scheme, so that the results are consistent with the obtention of amplification saturation. Moreover, more recent results demonstrate a large amplification of the 4d-4p transition of Ni-like Kr at 31.2 nm.