Phase-locked picosecond optical parametric oscillator

We report a degenerate self-phase-locked picosecond optical parametric oscillator (OPO) synchronously pumped by a mode-locked Yb-fiber laser at 1064 nm, delivering broadband output near 2 µm with 2.8 W of average power at ∼80MHz repetition rate. By exploiting a 50-mm-long MgO:PPLN crystal providing high gain and low group velocity dispersion under type-0 (e→ee) phase matching, the OPO generates a phase-locked degenerate output spectrum with a bandwidth of ∼202nm centered at 2128 nm in pulses of ∼21ps duration with excellent passive long-term power and spectral stability in high spatial beam quality. Phase-locked operation results in spectral and power stabilization at exact degeneracy and is further validated by f-2f interferometry and radio frequency measurements of OPO output. To the best of our knowledge, this is the first degenerate self-phase-locked OPO in picosecond time scale, and the highest average power reported for a phase-locked ultrafast OPO to date.