Effect of mechanical inhomogeneity on intrinsic stress birefringence in birefringent optical fibres

It is found that, for two specific types of birefringent fibre, the differences in Young´s modulus and Poisson´s ratio between the stress-producing regions and the surrounding cladding have a significant effect on the residual stress birefringence. This is because of the mechanical perturbation produced by the thermal effect in other regions of the fibre and the thermal stress level produced on the boundary during cooling.