Spectral characterization of second harmonic chi((2)) cascading phenomena

The second harmonic generation in a thin beta -barium borate crystal is use d to measure chi ((2)) cascading phenomena in the spectral domain. The harm onic generation is induced by two pulses produced by spectrally filtering a femtosecond pulse and centered at the wavelength lambda-Delta lambda and l ambda+Delta lambda. New spectral components appear in spectral density of b oth the fundamental and harmonic pulses. High order cascading phenomena are evidenced. In good agreement with theoretical predictions, for large phase mismatch the evolution of the spectra demonstrates the competition between cascaded chi ((2)) and chi ((3)) phenomena. (C) 2001 Optical Society of Am erica.