Birefringence optimization in PM fibers by specifically influencing the draw induced intrinsic stresses

Intrinsic stress in optical fibers significantly influences the mechanical properties of glass and modifies the refractive index. This can have an impact on fiber stability and modal behavior. Corresponding effects are often undesired but in some cases essential for certain applications, e.g. in polarization maintaining (PM) fibers. Stresses in optical fibers are caused by various reasons like differences in the thermal expansion coefficient of differently doped fiber regions or the mechanical force applied during the fiber drawing process. Understanding the reasons for stress generation and thus birefringence yields the opportunity to optimize this special property of PM fibers.