Generation of 10 to 50 fs pulses tunable through all of the visible and the NIR

Noncollinearly phase-matched optical parametric amplifiers (NOPAs) pumped b y the blue light of a frequency-doubled Ti:sapphire regenerative amplifier are a convenient source of continuously tunable ultrashort pulses in the vi sible and near infrared for spectroscopic experiments. We present the under lying principles, report recent improvements and describe the experiences g ained from the routine use of a number of NOPAs in our laboratories. We fin d that the setup can easily be optimized for the given experimental require ments. Typical output-pulse energies in the visible are 5 to 10 mu J and a few mu J in the NIR from 200 mu J regenerative-amplifier pulses at 800 nm. From 460 to 700nm, pulse lengths between 10 and 20fs are routinely achieved , while the length increases monotonically from about 20 fs at 900 nm to ju st below 50 fs at 1600 nm. In all cases this corresponds to a dramatic shor tening compared to the length of the pump pulses of around 100 fs. First re sults show that the 700 to 900 nm region can be accessed with sub-50-fs pul se lengths by use of an intermediate white-light generator in a two-stage s etup.