Few-cycle near-infrared pulses from a degenerate 1  GHz optical parametric oscillator

We report the generation of transform-limited 4.3-cycle (23 fs) pulses at 1.6 μm from a degenerate doubly resonant optical parametric oscillator (OPO) pumped by a 1 GHz mode-locked Ti:sapphire laser. A χ(2) nonlinear envelope equation was used to inform the experimental implementation of intracavity group-delay dispersion compensation, resulting in resonant pulses with a 169 nm full width half-maximum spectral bandwidth, close to the bandwidth predicted by theory.