Mandrel Wrapping

Mandrel wrapping is a technique used to preferentially attenuate high order mode power of a propagating optical signal.
It consists of the wrapping of several turns of optical fibre around a mandrel approximately 1 cm in diameter in order to filter out excess high-order modes that are launched into the optical fibre.
If the fibre is propagating substantial energy in affected modes, the modal distribution will be changed.

For multimode fibre optics, a technique used to modify the modal distribution of a propagating optical signal.