High-repetition-rate, all-solid-state, Ti:sapphire-pumped optical parametric oscillator for the mid-infrared

We report a low-pump-threshold, all-solid-state subpicosecond optical parametric oscillator (OPO) for the mid-infrared based on periodically poled ${\mathrm{LiNbO}}_{\mathrm{3}}$ and synchronously pumped by a mode-locked Ti:sapphire laser. Using a semimonolithic cavity design and hemispherical focusing, pump power thresholds of 17 mW and mid-infrared idler powers of 64 mW have been obtained in the 3.9–6 μm spectral range in a simple, practical, and compact configuration at pulse repetition rates of up to 322 MHz. The OPO delivers a signal output power of up to 280 mW at ∼35% extraction efficiency and can provide transform-limited signal pulses with durations of 0.4 ps over the spectral range of 1.00–1.14 μm.