Compact tunable 80 MHz repetition rate vacuum ultraviolet light source up to 10 eV: intracavity high harmonic generation by nonlinear reflection on a AlN nanofilm in a mode locked Ti:sapphire oscillator.

We report the realization of an intra-oscillator high harmonic source based on a Kerr lens mode locked Ti:sapphire laser running at 80 MHz repetition rate. A nonlinear medium consisting of an AlN nanofilm on a thin sapphire substrate is placed inside the oscillator cavity. The harmonics are generated, in reflection geometry, on the AlN nanofilm, directing the harmonic beam out of the cavity. Exploiting the benefits of this approach, a compact size, tunable, high repetition rate and coherent vacuum ultraviolet light source with a spectrum up to the 7th harmonic has been achieved. In particular, the powerful 5th harmonic covering the 145-163 nm range aims to be an attractive tunable light source for spectroscopical applications.