Ultrafast laser system based on noncollinear optical parametric amplification for laser spectroscopy

We report the experimental demonstration of transform-limited sub-6 fs pulses at an optimal central wavelength by a tunable noncollinear optical parametric amplification (NOPA) source. Meanwhile, a white light continuum in the near-infrared (NIR) range from 900 to 1100 nm is also successfully generated by focusing the unconverted 800 nm beam during NOPA generation on a sapphire rod. Both visible-pump/visible-probe and visible-pump/NIR-probe experiments are realized using the same laser system. As examples, ultrafast photo-induced exciton dynamics inside two kinds of materials are investigated by the visible-pump/visible-probe and visible-pump/NIR-probe spectroscopy, respectively.