Numerical analysis of residual stresses in preform of stress applying part for PANDA-type polarization maintaining optical fibers

This study is concerned with numerical simulation of the mechanisms responsible for formation of technological and residual stresses in preforms of non-uniformly doped silica stress applying rods for optical fibers of PANDA-type caused by cooling and etching of the upper layers. The relationships between the doping degree and the rod radius meeting the strength criterion have been established. It has been found that doping of the stress applying rod with doping additives compensating the refractive index increases the level of the stress state. To take account of this effect a set of doping relationships acceptable for compensated rods has been proposed.