Research On Sensing Characteristics Of Modal Interferometers Based On Tapered All-solid Photonic Bandgap Fiber

The emergence of all-solid photonic bandgap fiber has solved the problems in the air-core photonic bandgap fibers, such as difficulty of fabrication and splicing to single-mode fibers. The all-solid photonic bandgap fiber is the structure that guides modes with the bandgao effect. Due to its unique light-guilding characteristics, it has been widely used in optical fiber communication and sensor areas. In recent years, integrating the modal interferometer within an optical fiber has become a important topic for many research groups. This interferometer is featured with compactness, high intergration, stability, and so on.. This paper mainly discuses fabrication of two kinds of modal interferometers based on all-solid photonic bandgap fibers and their potential applications in measurement of refractive index, temperature, and/or strain stress.Firstly, we propose an approach for a modal interferometer structure based on all-solid photonic bandgap fiber, and investigate its light guiding properties. We utilize the welding machine to fabricate two different sizes of the modal interferometers, measure the temperature and refractive index responses, theoretically describing the mechanisms, and analyze the influence of structure sizes.Secondly, we propose and fabricate an all-solid photonic bandgap fiber modal interferometer with two tapers. Using a splicer, we introduce two abrupt fiber tapers to realize the modal coupling and interference. Good interference fringes are observed. The temperature and stress responses are investigated and discussed in detail.We have theoretically described the mechanism of of the modal interferences based on the tapered all-solid photonic bandgap fibers. Our research not only provides a deep understanding to the modal interference in the bandgap fiber, but only provides a useful investigation on such interferometers based on all-solid bandgap waveguides. We believe that the proposed devices have many potential application in optical communication and sensing fields..