We demonstrate, for the first time to our knowledge, that efficient third-harmonic generation can be achieved with a cubic contribution much larger than the quadratic processes. An energy-conversion efficiency of 2.4% is achieved for cubic third-harmonic generation that is phase matched along the x axis of a KTiOPO<sub>4</sub> crystal by use of a picosecond fundamental laser emitting at 1618 nm. The associated cascading processes are only 10% of the pure cubic interaction, which is very suitable for study of the specific quantum optical correlations. Calculations of the third-harmonic generation conversion efficiency with respect to group-velocity dispersion and to the longitudinal Gaussian beam profile account well for our experimental results.
© 2000 Optical Society of America
J. P. Fève, B. Boulanger, and Y. Guillien, "Efficient energy conversion for cubic third-harmonic generation that is phase matched in KTiOPO4," Opt. Lett. 25, 1373-1375 (2000)