Very compact soft x-ray lasers and their potential applications

The results of two different series of experiments on generation lasing action in the soft x-ray region are presented. In the first series lasing in hydrogen-like Li III ions at 13.5 nm (2-1 transition to ground state) in a 5 mm long LiF microcapillary at 2 Hz repetition rate is demonstrated. The initial plasma was created in a 0.3 mm diameter microcapillary by a low power Nd:YAG laser (0.1 J in 5 ns), whereas the plasma pumping was proceeded with a 50 mJ, 250 fs UV laser. In the second series lasing is demonstrated in hydrogen-like B V ions at 26.2 nm (3-2 transition) using a very small Nd:YAG pumping laser (0.45 J in 8 ns) at a repetition rate of 1 Hz. The preplasma in a B2O3 microcapillary was created from wall ablation with a 0.2 J (20 ns) KrF laser, and the whole soft x-ray lasing system takes up less space than is available on a 1.2 m x 3 m optical table. In the last part of the paper the development of soft-x-ray lasers (SXLs) for application in lithography and soft x-ray microscopy is discussed.