Low Birefringence Measurement and Temperature Dependence in Meter-Long Optical Fibers

We propose a relatively simple technique to infer the birefringence on single mode low-birefringence optical fibers based on the use of the Faraday effect. The theoretical model for Faraday rotation in the presence of nonnegligible fiber birefringence and a suitable measurement technique offer a fast and efficient way to determine low values of linear birefringence employing short fiber lengths. Alternative known techniques are not sensitive enough or they are of more difficult implementation. The method is used in only ~1 m-long single-mode optical fibers to obtain the upper-limit birefringence that can be tolerated in order to retain good current sensing sensitivity. The temperature dependence of the Faraday rotation and its causes are also investigated.