Enhancement of nonlinear optical interactions in the core of a photonic-crystal fiber allows several χ<sup>(3)</sup> processes to be simultaneously observed in the field of unamplified 30-fs pulses of a Cr:forsterite laser. Subnanojoule fundamental-radiation pulses of this laser experience spectral broadening arising from self-phase modulation and generate the third harmonic at 410–420 nm. Third-harmonic pulses also appear spectrally broadened at the output of the fiber as a result of the cross-phase-modulation effect. This catalog of enhanced χ<sup>(3)</sup> processes observed in photonic-crystal fibers opens the way for using such fibers for frequency conversion of low-energy femtosecond pulses with simultaneous chirp control and subsequent pulse compression.
© 2002 Optical Society of America
Aleksandr N. Naumov, Andrei B. Fedotov, Aleksei M. Zheltikov, Vladislav V. Yakovlev, Leonid A. Mel'nikov, Valentin I. Beloglazov, Nina B. Skibina, and Andrei V. Shcherbakov, "Enhanced χ(3) interactions of unamplified femtosecond Cr:forsterite laser pulses in photonic-crystal fibers," J. Opt. Soc. Am. B 19, 2183-2190 (2002)