High-contrast, high-brightness ultraviolet laser system.

In this paper, improved operation of a high-contrast, high-brightness ultraviolet laser system is described. The laser system is based on a conventional short-pulse dye/excimer design, modified to contain 3 KrF excimer short-pulse amplifiers and the recently developed nonlinear Fourier-filtering stage for contrast improvement. The final amplifier accepts a beam size of ~4x4 cm, producing 100 mJ energy of short-pulses using a two-beam interferometric multiplexing setup. Temporal measurements of the output showed positively chirped pulses of ~700 fs duration, beside a focusability of ~2 times the diffraction limit. Amplified spontaneous emission-as the only source of the temporal background-results in a focused intensity contrast of >10 in the entire temporal window. These unique parameters give access to laser-matter interaction experiments above 10 W/cm intensity at 248 nm.