Optical fibre with low dopant region between centre and outer part of fibre

摘要

An optical transmission system includes an optical fibre with a core 12 with a first refractive index peak, an outer layer 16 with a second refractive index peak higher than the first, and a low-dopant region 14 between the two. The low-dopant region may have a refractive index difference Dn with an absolute vale less than or equal to 15% of the peak fibre refractive index difference.