High-power picosecond mid-infrared optical parametric amplifier for infrared Raman spectroscopy

A high-power (50-MW), kilohertz, picosecond, mid-IR optical parametric amplifier that is pumped by an amplified Ti:sapphire laser and also produces a fixed-frequency visible pulse is described. Mid-IR pulse energies of 40–55 $\mathit{\mu }\mathrm{J}$ with 0.6–0.8-ps durations and $35-{\mathrm{cm}}^{-1}$ bandwidths are reported in the 3650–$2800-{\mathrm{cm}}^{-1}$ range. The combination of picosecond mid-IR and visible pulses is useful for two-color spectroscopies, which require simultaneous time and frequency resolution. To illustrate the above, we present vibrational relaxation data for the polyatomic molecule nitromethane, using time-resolved infrared Raman spectroscopy.