Wide and fast dispersion tuning of a picosecond OPO based on aperiodic quasi-phase matching using an axially chirped volume Bragg grating.

We report on a widely tunable synchronously pumped picosecond optical parametric oscillator (OPO) combining an aperiodically poled MgO-doped LiNbO₃ crystal as a broadband gain medium and an axially chirped volume Bragg grating as a spectral filtering dispersive element. Translation of the Bragg grating along the beam axis enables wavelength tuning over 215 nm around 3.82 μm and provides spectral narrowing. Rapid continuous tuning over 150 nm in 100 ms is demonstrated.