A collinearly phase-matched parametric generator/amplifier of visible femtosecond pulses

We report on the generation and amplification of ultrashort pulses of ≈1.5-μJ energy, tunable in the visible down to 456 nm, through travelling-wave parametric interaction in a single β-BaBO 4 crystal, operated in type-I phase matching and collinearly pumped by frequency-doubled Ti:sapphire pulses with the fronts suitably tilted to match the group velocities.