Efficient type I second-harmonic generation of subpicosecond laser pulses with a series of alternating nonlinear and delay crystals

Temporal solitons in second-harmonic generation with a noncollinear phase-mismatching scheme

A noncollinear second-harmonic-generation scheme that includes two gratings and a nonlinear optical crystal generates temporal solitons with a noncollinear phase mismatch and frequency-chirped laser pulses. At 180-fs pulse duration, 25-GW/cm2 fundamental intensity, -7647.3-m(-1) wave-vector mismatch, 66-fs delay time, and +/-3.07163 x 10(25) s(-2) frequency-chirp rates, temporal solitons with durations from 139 to 155 fs and Gaussian shapes can be obtained. The corresponding conversion efficiency is greater than 40%.

Simultaneous spatial and temporal walk-off compensation in frequency-doubling femtosecond pulses in beta-BaB(2)O(4)

We experimentally demonstrate the benefits of simultaneous compensation of spatial and temporal walk-off in frequency doubling of 800-nm 250-fs pulses, using three active and two compensating beta-BaB(2)O(4) crystals. The compensating crystals reverse both birefringent and group-velocity walk-off, resulting in a factor-of-4.5 improvement in doubling efficiency relative to one of the active crystals while maintaining the short pulse duration and the symmetric spatial profile that are characteristic of the single crystal.