SINGLE-MODE, SINGLE-POLARIZATION OPTICAL FIBER

摘要

A single-mode, single-polarization optical fiber ("PZ fiber") can have a large single-polarization wavelength bandwidth when .eta. (as herein defined) for one symmetry axis is positive when calculated from the refractive index profile determined with one of two orthogonal orientations of polarized light and is negative when calculated from the refractive index profile determined with the other orientation, and for each other symmetry axis of the novel optical fiber .eta. is positive for both orientations of plane polarized light. Preferably the absolute values for .eta. when positive and .eta. when negative are about equal for said one symmetry axis. A preferred PZ fiber can be formed by depositing siliceous layers onto the interior surface of a hollow substrate tube of quartz to provide a preform. After forming two parallel flat faces in its outer surface, the preform is pulled to form a PZ fiber having an elliptical stress-applying region.