Novel characterisation concepts for preforms and fibres

Refractive index profile of an Al/Yb doped preform.

The MCVD process is powerful but also quite complex. Adjustment of the dopant profiles and the bonding structures, which control nearly all optical fibre properties, must be done iteratively by off-line characterisation and feedback into the MCVD process. A serious issue is that most off-line characterisation concepts are destructive. Furthermore, several distinct measurement approaches such as Raman and NMR-spectroscopy must be combined to obtain full information about all dopants and bonding structures. Thus, it is our long-term vision to develop novel and non-destructive characterisation concepts, which combines the individual measurement approaches. These concepts will allow us, to develop fibres with unseen quality and novel functionalities.