Group-velocity-matched noncollinear second-harmonic generation in quasi-phase matching

Abstract

We demonstrate group-velocity-matched second-harmonic generation of 80-fs pulses under noncollinear quasi-phase-matching (QPM) geometry. Second-harmonic pulses of 100-fs duration, 11-nm bandwidth, and0.78-µm center wavelength were generated with 50% efficiency with 3-mm-long periodically poled lithium niobate. We have also numerically studied the dependence of conversion efficiency and pulse durations on pump intensity, propagation length, and noncollinear angle. It is confirmed that our group-velocity-matching scheme requires a much lower pump intensity than the conventional collinear QPM scheme.