Picosecond infrared optical parametric amplifier for nonlinear interface spectroscopy

A tunable, narrow bandwidth, high peak power picosecond infrared (IR) laser system is described. The pump source is a picosecond Ti:sapphire regenerative amplifier seeded by a picosecond Ti:sapphire oscillator. The pump bandwidth and pulse duration are tunable producing 4–5 ps, 5–4 $cm−1$ pulses at 1 kHz. IR pulses are produced by optical parametric generation (OPG) followed by optical parametric amplification (OPA). Tuning is possible over the entire 1050–3300 nm region of the IR, with energies in excess of 15 μJ over most of the range. The temporal and spectral characteristics of the IR pulses are reviewed with a particular focus on the sources of bandwidth broadening in the OPG/OPA. Bandwidth optimization of the IR output is discussed. A spectral filtering scheme results in less than 15 $cm−1$ IR bandwidth, suitable for nonlinear optical spectroscopic applications.