BIREFRINGENT SPLITTABLE COMPOSITE (BISPEC) FIBER AND POLARIZATION-MAINTAINING COUPLERS

A novel technique for the fabrication of BI refringent SPlittablE Comp osite (BISPEC) fiber is reported, We describe in details the design co nsideration, practical fabrication, and characterization of this fiber . The distinctive feature of this fiber is that the principal axes of the constituent fibers can be accurately aligned in the preform stage so that long lengths of well-aligned fiber can be drawn. We further de monstrate the application of this fiber by fabricating a polarization- maintaining coupler by simply introducing a local taper. Measurements show that such a coupler can have polarization extinction ratio as lar ge as 31 dB (in the best case).