A Fermat's spiral multifilament-core fiber

A multifilament-core optical fiber where the microstructure is arranged in a Fermat's spiral is presented. The properties of such a fiber to be exploited for laser light amplification are numerically investigated by means of a full-vectorial finite-element method. Thanks to this peculiar microstructure, the fiber is shown to have an increased Brillouin threshold power and very low bending losses, while preserving a very good beam spatial quality.

► A new design for a multifilament-core fiber is proposed.
► The distinctiveness of the geometry leads to a decrease of the Brilluoin gain.
► Bending losses are reduced as well.