Research On The Intelmodal Interference In Panda Fiber And Bowtie Fiber

The intermodal interference technology is based on theLP0 1andLP11interference to realized the measurement of physical quantities. The output light intensitydistribution has an oscillatory two-lobe pattern manner which is modulated by theexternal disturbance. In that case, if one or two lobes intensity is monitored, the externaldisturbance that caused the changes of output light intensity can be measured.The intermodal interference in panda fiber and bow-tie fiber, however, have notbeen examined roundly. In this letter the intermodal interference charateristics of bothfundamental and second-order modes in Hi-Bi panda fiber and bow-tie fiber areinvestigated thoroughly. This paper provides the theory foundation and experiment set upfor building new types of fiber-optic sensors such as voltage transducers and straingauges based on intermodal interference of panda fiber and bow-tie fiber.The main works in this paper as follows.Firstly, we introduced the background for this research, the development status ofintermodal interference technology and PMF today. Then the problems in designingoptical sensors with panda fiber or bow-tie fiber are proposed.Secondly, applying the finite-element method the von Mises stress patterns,propagation characteristics and electronic interference distributions ofLP0 1andLP11in panda fiber and bow-tie fiber are analyzed.Thirdly, the intermodal interfernce characteristics of panda fiber, ellptical core fiberand two-hole photonic crystal fiber are analysised comparatively which is useful fordesigning intermodal interference sensors with proper two-mode fiber which can improvethe performance of the sensors.At last, an experiment was set up to verify the feasibility of modular interferencesensors based on panda fiber. Further more, the modular interference beat lengthLMand intermodular interference progation constant differenceΔβare calculated with thissystem. The experiment results indicate that the two modular interference output lobes’ intensity will exchange with each other when extern strain is applied on the panda fiber.The results in this paper provide theory foundation and experimental verification forbuilding novel fiber-optic sensors based on modular interference technology with Pandafiber and bow-tie fiber.