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 β-BaB<sub>2</sub>O<sub>4</sub> 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.
© 1998 Optical Society of America
Russell J. Gehr, Mark W. Kimmel, and A. V. Smith, "Simultaneous spatial and temporal walk-off compensation in frequency-doubling femtosecond pulses in β-BaB2O4," Opt. Lett. 23, 1298-1300 (1998)