Research On The Modular Interference Characteristics Of Elliptical-core Pola-ization Maintenance Optic Fiber

The intermodal interference technology in polarization maintaining opticalfiber(PMF) is based on intermodal interference in a single PMF to realize themeasurement of physical quantities. Compared with the traditional interferometer’s twoarms structure, the optical sensor of intermodal interference has simple structure andbetter system stability. So it attracted the attention of the field of optical fiber sensing inrecent years.The research on intermodal interference of elliptical core optical fibers has attainedremarkable achievements, but the properties of intermodal interference in elliptical corefiber are still lacking depth theoretical and experimental studies.In addition, the modes inelliptical-core optical fiber and numerical analyse haven’t formed to be a systematicanalysis. In order to investigate the intermodal interference in elliptical core fiber, themodes which can propagate in elliptical core fiber and the influence of the fiberconstructure parameters on the intermodal interference was discussed And one of theapplication parameters the temperature sensitivity coefficient was given.Firstly，based on theory of modes in fiber and full-vector finite element analysissoftware, the relationships between line polarization modes and vector modes in weaklyguiding fiber were analysised.The electronic distribution of the modes in elliptical corefiber were calculated.Secondly, the parameters which influence the performance intermodal interference inelliptical core fiber were analysised and calculated completely, And the relationshipbetween those parameters with the constructure parameters of elliptical core fiber and theoperating wavelength were obtained.Thirdly,the influence of changing temperature to the intermodal interference inelliptical core fiber was calculated theoretically. The temperature sensitivity in ellipticalcore fiber was calculated by the finite element method and Marcatili method. respectively.Compare the two results from the two methods, we can see that the results calculated byfinite element method is more accurately than those calculate by Marcatili method. At last, an experiment was setup to verify the influence of temperature to theintermodal interference in elliptical core fiber, and the temperature sensitivity coefficientwas measured.