The common perception “the smaller it is, the most technologically advanced” does not apply to the fibre core of a single mode (SM) laser, whose quality is not defined by the size, but by the material it is made of.
Small-diameter core are easier to design, that's why most manufacturers opt for this solution. The core size, nevertheless, is not an irrelevant factor: larger-diameter fibre cores guarantee a high level of protection to back-reflection and to nonlinear effects. This allows the manufacturer to produce long delivery fibres.
Thanks to its expertise and proprietary technology, Fujikura can deliver SM laser sources with large-diameter core fibres with a delivery fibre longer than 10 m.
