Extreme ultraviolet light source based on intracavity high harmonic generation in a mode locked Ti:sapphire oscillator with 9.4 MHz repetition rate.

We report on the realization of an intracavity high harmonic source with a cutoff above 30 eV. The EUV source is based on a high power, hard-aperture, Kerr-lens mode-locked Ti:sapphire oscillator with a repetition rate of 9.4 MHz. The laser is operated in the net negative dispersion regime resulting in intracavity pulses as short as 17 fs with 1 µJ pulse energy. In a second intracavity focus, intensity more than 10¹⁴ W/cm² has been achieved, which is sufficient for high harmonic generation in a Xenon gas jet.