Single-step sub-200  fs mid-infrared generation from an optical parametric oscillator synchronously pumped by an erbium fiber laser

By: Bernd Metzger, Benjamin Pollard, Ingo Rimke, Edlef Buettner, and Markus B. Raschke

Opt. Lett. 41, 4383 (2016)

We demonstrate the single-step generation of mid-infrared
femtosecond laser pulses in a AgGaSe2 optical parametric
oscillator that is synchronously pumped by a 100 MHz
repetition rate sub-90 fs erbium fiber laser. The tuning
range of the idler beam in principle covers ∼3.5 to
17 μm, only dependent on the choice of cavity and mirror
design. As an example, we experimentally demonstrate idler
pulse generation from 4.8 to 6.0 μm optimized for
selective vibrational resonant molecular spectroscopy. We
find an oscillation threshold as low as 150 mW of pump
power. At 300 mW pump power and a central wavelength
of ∼5.0 μm, we achieve an average infrared power of up to
17.5 mW, with a photon conversion efficiency of ∼18%. A
pulse duration of ∼180 fs is determined from a
nonlinear cross-correlation with residual pump light. The
single-step nonlinear conversion leads to a high power stability
with <1% average power drift at <0.5% rms noise
over 1 h.