Beat-length measurement of high-birefringence polarization-maintaining optical fiber using the dc Faraday magneto-optic effect

The polarization-maintaining (PM) capability of a high-birefringence (hi-bi ) optical fiber can be described in terms of its modal birefringence or bea t length. In the hi-bi (PM) fiber the beat length can be measured by changi ng the state of polarization of the light through an external means. One su ch technique is based on the Faraday magnetooptic effect. The technique is nondestructive, relatively simple, and efficient, and beat lengths of 2 mm and less have been measured accurately with it, thus fulfilling the measure ment requirements for many of the currently available PM fibers. Utilizing optical sources with wavelengths of 633 and 814 nm, the beat lengths in a t otal of four hi-bi fibers have been successfully measured using the de Fara day magneto-optic effect. The experimental results are comprehensive and ve ry promising, and it has been demonstrated that this nondestructive techniq ue has significant advantages over many others in simplicity, versatility. productivity, practicality, and accuracy. (C) 2000 Society of Photo-Optical Instrumentation Engineers.