Abstract

Photonic crystal fibre (PCF) has attracted sustained attention in the ultrafast optics community because of its unusual properties which include super-continuum generation enhanced by four-wave mixing and soliton transmission. In this paper we discuss operation in a regime where well-defined near-infrared output spectra are generated at red-shifted wavelengths up to 450 nm longer than the input with strong depletion at the original pump wavelength of 810 nm. We attribute the effect to the soliton self-frequency shift^1,2 in which Raman self-pumping of the soliton continuously transfers energy from shorter to longer wavelengths, so causing a redshift of the pulse centre wavelength. Similar results were recently reported for 1.3 μm pumping in a tapered air-silica microstructure fibre³ but to our knowledge we report here the first observation for direct pumping at 800 nm. The only previous demonstration of the soliton self-frequency shift in standard PCF was realised using a fibre with a zero-dispersion wavelength of 800 nm and 1.5 μm pump pulses which resulted in a shifted output centred at 1.7 μm.⁴

© 2002 Optical Society of America