Tunability extension of ultrashort pulses from a solid-state kilohertz system to the violet-blue region by use of hollow waveguides

Summary form only given. The generation of intense ultrashort laser pulses tunable in the violet-blue region (350-450 nm) of the electromagnetic spectrum has long been hampered by the lack of suitable lasing media. Continuum generation with lasers operating at longer wavelengths, with subsequent amplification and compression stages, has been shown to produce <50-fs pulses only at wavelengths >480 nm. Parametric generation of near infrared, followed by multiple harmonic and/or sum-frequency generation stages can deliver tunable femtosecond pulses at the cost of a slightly more complex setup. In this contribution, we demonstrate alternative approaches for the generation of femtosecond violet-blue pulses with the hollow waveguide technique. As a first approach, we show that second-harmonic generation of <20-fs broadband near-infrared light leads to 40-fs pulses with full tunability in the violet-blue region. In a second approach, we upconverted the output of our laser system, resulting in 200-/spl mu/J 50-fs 7-nm broad blue pulses, which were then injected into a hollow fiber. A BBO crystal for the upconversion introduces a linear chirp, which enhances the broadening due to self-phase modulation.