Recent advances in optical parametric processes in the femtosecond time domain

Until recently, nearly all the experiments on ultrafast processes in the femtosecond time domain have made use of sources derived directly and indirectly from the Rh6G dye laser. The development of the mode-locked solid-state Ti:sapphire laser has changed the situation fundamentally. With high repetition rate Ti:sapphire lasers now capable of generating sub-100 fs pulses to the 3 W range, it is now possible to extend the wavelength range of high repetition rate femtosecond sources to cover the entire spectral range from the near UV well into the mid-IR by a variety of nonlinear optical processes. One particularly significant recent development has been the broadly tunable high-repetition rate femtosecond optical parametric oscillators. Using KTP as the active medium, Ti:sapphire laser pumped OPO can tune continuously from nearly 900 nm to close to 4 μm at power levels in the hundreds of mW range. Precisely synchronized pulses at up to six wavelengths simultaneously that are also broadly tunable have been generated using fs OPO´s,