Study of the radiation scattering indicatrix in fibres heavily doped with germanium oxide

The original setup for measuring the radiation scattering indicatrix in a broad angular range from 1 to 179° is developed. It is shown experimentally that total optical losses in single-mode fibres heavily doped with germanium oxide are determined by optical losses caused by fundamental mechanisms and by anomalous scattering. The analysis of the anomalous scattering indicatrix and the spectral dependence of excess optical losses showed that anomalous scattering is caused by scattering from fluctuations of the fibre core–cladding interface along the fibre length. The mechanism of these fluctuations is proposed and substantiated.