PRODUCTION OF POLARIZATION-KEEPING OPTICAL FIBER

摘要

PURPOSE:To produce a polarization-keeping elliptic-core optical fiber having long length and low transmission loss at a low cost by boring a pair of holes through a clad of a cylindrical optical fiber preform in a state holding a core between the holes in a direction perpendicular to the axis and extending in the direction of the axis, heating the bored preform to collapse the holes and drawing the product. CONSTITUTION:A nearly cylindrical glass preform 12A for optical fiber composed of a core 10 and a clad 11 is prepared by VAD process. etc. A pair of oppositely placed holes 13, 13 extending in the direction of the fiber axis are bored through the clad 11 of the glass preform 12A in such a manner as to hold the core between the holes in a direction crossing the axis. The glass preform 12A is drawn after or simultaneous to heating the preform to collapse the holes 13, 13. A polarization keeping optical fiber 20 having an elliptic core 10 can be produced by this process. The obtained polarization-keeping optical fiber 20 is suitable for various communication devices using a linearly polarized light.