Abstract

We demonstrate generation and focusing of 49.7-nm pulses with an average power of 0.1 mW at 200 Hz and with a pulse energy of $>1 \mathit{\mu }\mathrm{J}$ at 10 Hz by the fifth harmonic of a femtosecond KrF laser. The fifth harmonic is selected and focused with a concave $\mathrm{Sc}/\mathrm{Si}$ multilayer mirror to a diameter of $2\mathit{\mu } \mathrm{m}$, resulting in a peak intensity of $0.5 \mathrm{TW}/{\mathrm{cm}}^2$, which will make extreme-ultraviolet nonlinear optics feasible. A novel single-shot linear in situ method of spot-size measurement by use of self-trapped exciton luminescence is also demonstrated.

© 2002 Optical Society of America

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