Third harmonic generation in self-focused filaments in liquids.
Intense filaments of third harmonic generation have been observed in a variety of liquids when pumped by 1300 nm wavelength femtosecond light. The onset of third harmonic generation coincides with the threshold for self-focusing as deduced from n(2) measurements performed on the liquids using the z-scan technique. We have found self-phase modulation above the threshold leading to continuum generation at about 3 times threshold. In the third-harmonic regime, the third harmonic output power is independent of the input power. Our observations are consistent with those for similar processes in gases as described by a phase-locking model. The measured conversion efficiency was approximately 10(6).
Mao
Guilin
G
Case Western Reserve University, Department of Physics, Cleveland, OH 44106-7079, USA. kenneth.singer@case.edu
Wu
Yeheng
Y
Singer
Kenneth D
KD