Frequency-doubling broadband light in multiple crystals

We compare frequency doubling of broadband light in a single nonlinear crys tal with doubling in five crystals with intercrystal temporal walk-off comp ensation and with doubling in five crystals adjusted for offset phase-match ing frequencies. Using a plane-wave dispersive numerical model of frequency doubling, we study the bandwidth of the second harmonic and the conversion efficiency as functions of crystal length and fundamental irradiance. For low irradiance, the offset phase-matching arrangement has lower efficiency than a single crystal of the same total length but gives a broader second-h armonic bandwidth. The walk-off-compensated arrangement gives both higher c onversion efficiency and broader bandwidth than a single crystal. At high i rradiance, both multicrystal arrangements improve on the single-crystal eff iciency while maintaining a broad bandwidth. (C) 2001 Optical Society of Am erica.