An experimental and theoretical study of intrinsic correlations and noise-suppression mechanisms in two-stage femtosecond mid-IR light sources is presented. The setup, based on parametric amplification in BBO and subsequent difference-frequency mixing in AgGaS<sub>2</sub>, delivers ≈100-fs mid-IR pulses with 1–2-μJ energy. Exceptionally low pulse-energy fluctuations of only 0.2% in the mid-IR (λ ≈ 3–6 μm) are found, which are much smaller than the Ti:sapphire amplifer noise. The noise suppression is analyzed and found to stem from the interplay between dispersion and pump depletion.
© 2000 Optical Society of America
Peter Hamm, Robert A. Kaindl, and Jens Stenger, "Noise suppression in femtosecond mid-infrared light sources," Opt. Lett. 25, 1798-1800 (2000)