Techniques for manufacturing birefringent optical fiber

In a technique for fabricating a birefringent optical fiber, a preform rod is fabricated having a longitudinal axis, an outer peripheral surface, and a selected refractive index variation. At least one longitudinal groove is cut into the preform rod through its outer peripheral surface, wherein the at least one longitudinal groove has a cross sectional area equal to that of a respective birefringence-inducing stress element to be loaded into the groove, such that when the stress element is loaded into the groove, a portion of the stress element protrudes outside of the circumference of the preform. A respective birefringence-inducing stress element is loaded into the at least one longitudinal groove. A preform assembly is created by positioning the loaded preform rod within an overcladding tube. The preform assembly is drawn into optical fiber.