Multicladding optic fibre and long period grating written in it

摘要

A multi-cladding optical fiber includes a core made of germanium-doped silica (GeO 2 -SiO 2 ), for guiding light, an inner cladding made of fluorine-doped silica (F-SiO 2 ), the inner cladding having a refractive index smaller than that of the core and surrounding the core, and an outer cladding made of silica, the outer cladding having a refractive index smaller than that of the core and larger than that of the inner cladding and surrounding the inner cladding. The refractive index of the core may be periodically changed by periodically annealing, eg using an arc discharge or CO 2 laser, the multi-cladding optical fiber, so that a stress-released long-period optical fiber grating can be obtained.