Beat-length measurement of birefringent optical fibers

We present a novel technique for the measurement of the beat length of birefringent single-mode fibers based on differential attenuation induced by a metal. The proposed technique is particularly suited for the measurement of local birefringence in polished-fiber semiplates. The technique should also find application in the characterization of polished fiber semiplates used in the fabrication of fiber directional couplers.