| 摘要 |
A method of forming an optical fiber joint between a pair of elongated optical fibers each of which has a longitudinal axis surrounded by a core and cladding having different refractive indices and forming a single-mode light-guiding region, the core and cladding of each fiber having non-circular transverse cross-sections defining two polarization-maintaining axes of birefringence transverse to the longitudinal axis of the fiber. Each of the fibers also has predetermined external flat reference surfaces for locating the core and cladding and the axes of birefringence within each fiber from the exterior geometry of the fiber. The method comprises shaping an elongated glass preform to have a cross-sectional configuration with flat longitudinal surfaces extending along the preform length, which flat surfaces are large-scale complements of the external reference surfaces on the fibers to be joined, such that the preform longitudinal surfaces will mate with the fiber reference surfaces when the preform is drawn down to the scale of the fibers; heating the shaped preform to a softened condition and then drawing the softened preform in a longitudinal direction to reduce the scale of the complementary surfaces so that the cross-sectional configuration of the drawn preform matches the cross-sectional configuration of the external reference surfaces on the fibers to be joined, and so that the preform longitudinal surfaces and the fiber reference surfaces will mate together; cooling the drawn preform and placing the optical fibers to be joined thereon with the ends of the fibers butted together, with the external reference surfaces on the fibers matingly engaging the complementary longitudinal surfaces on the drawn preform; and bonding the fibers to the drawn preform and bonding the abutting ends of the fibers to each other.
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