Dispersion tuning of a narrow-linewidth picosecond OPO based on chirped quasi-phase matching with a volume Bragg grating

We report on a widely tunable synchronously-pumped picosecond OPO combining an aperiodically poled MgOdoped LiNbO 3 crystal as a broadband gain medium and an intracavity axially chirped volume Bragg (VBG). Owing to the high dispersion induced by the chirped VBG, only a narrow spectral band, corresponding to a thin slice of the VBG, satisfies the synchronous-pumping condition. At a fixed position, the VBG is thus a narrow-band filtering element; variation of its position along the cavity axis enables to tune the idler wavelength over 215nm around 3.82 μm. Rapid continuous tuning over 150nm in 100 ms is also demonstrated.