IMPROVEMENTS IN AND RELATING TO PHOTONIC-CRYSTAL FIBRES AND PHOTONIC-CRYSTAL FIBRE DEVICES

摘要

A photonic-crystal fibre comprises a core (20) and a cladding (10) with longitudinal holes. The refractive index of the core is lower than that of the cladding bulk material, e.g. by fluorine doping of the core material. The holes are air-filled cavities extending along the longitudinal direction of the fibre. One property of the fibre is that a guided mode having longer wavelength is more confined in the core than a mode with a shorter wavelength. Such a fibre may have a cut-off wavelength lambda c such that the fibre is unable to guide in its core light of wavelengths shorter than lambda c.