Abstract

Highly birefringent single-mode fibers have been fabricated according to several different approaches. Historically the first successful approach was to design the fiber to have a highly doped elliptical cladding, which, because of the different thermal contractions of the cladding and the outer substrate tube, introduces a large stress asymmetry and thus birefringence β in the core region of the fiber.^1,2 This design has produced fibers with beat lengths L_p = 2π/β down to a few millimeters and a polarization-holding parameter as low as h ≃ × 10⁻⁶ m^−1, corresponding to an average polarization holding of 22 dB over 1 km.³

© 1983 Optical Society of America