Single-polarisation single-mode guidance in stress-induced birefringence fibres with lossy stress-applying sections

When the refractive index of the stress-applying sections in a stress-induced birefringence fibre lies between the effective indices of the two polarisation modes, the polarisation mode with lower effective index is essentially guided by the stress-applying sections. Single-polarisation guidance can thus be achieved by introducing absorption loss in the stress-applying sections.