Measurement of beat length in polarization-maintaining fibers with external forces method

Beat length is a key parameter for the polarization maintaining fibers (PMFs). Based on a white light scanning Michelson interferometer, the measurement of the phase beat length in PMFs employing the external force is presented. When the linearly polarized light propagates along the principal axis of the PMFs, the polarization coupling occurs at the force position of PMFs. The short and long length PMFs are measured respectively, furthermore, the uniformity of beat length measurement is tested. In the end, the advantages and the disadvantages of the method are discussed in detail.

► The beat length measurement in PMFs with external forces based on white light interferometry is proposed.
► The method is suitable for both short and long length PMFs measurements.
► The advantages and the disadvantages of the method are discussed in detail.
► The accuracy, the SD and the uniformity of measurement are 19 μm, 29 μm and less than 30 μm respectively.