Abstract
Outstanding progress in soft x-ray lasers. has been made during these 10 years since thefirst demonstration of soft x-ray amplification in 1984. This paper reviews current efforts andprogress in extensive approaches to realize soft x-ray lasers as a laboratory tool. The use ofoptical-field-induced ionization by an ultrashort high-intensity laser is a promising approach. Two types of a soft x-ray laser based on the recombination and the electron collision excitationfollowing the optical-field-induced ionization are discussed. The significant progress in the reductionof the necessary pump energy of a conventional collisional scheme and the demonstration of a large gain-length product in a conventional recombination scheme are also described.In addition to these laser-based approaches, the first demonstration of a capillary discharge XUV laser based on an electron collision excitation is presented.
