Abstract

Microstructure (or holey) fibers,^1–4 i.e., fibers where a cladding has a form of a two-dimensional (often periodic, i.e., photonic-crystal) array of closely packed glass capillaries drawn at a high temperature, have been shown recently to considerably enhance various nonlinear-optical processes due to the high degree of light localization in the fiber core. High light intensities, attainable by coupling nonamplified femtosecond laser pulses into a small core of a holey fiber, allowed the observation of enhanced spectral broadening of ultrashort laser pulses,⁴ self-phase modulation,^2,4 supercontinuum generation³ starting with subnanojoule energies of Ti: sapphire laser pulses. Second- and third-harmonic generation in holey fibers has been also demonstrated by Ranka et al.⁵ using a Q-switched Nd: YAG laser operating at 1064 nm.

© 2002 Optical Society of America