Research On Cladding Mode Resonance Sensing Characteristics Based On Triple Cladding Quatez Specialty Fiber

In recent years, fiber optic sensor has received extensive attention and research due to its unique advantages, and it has been successfully used in many areas, such as aerospace, construction engineering, biomedicine, etc. However, the balance between the simple structure and the superiority performance of these sensor is becoming a “bottleneck” which has already restricted the development of this field. Utilizing the structure characteristics of multi-cladding fiber, the cladding mode resonance fiber sensor makes the light transmitted from core and cladding couple with each other, so as to realize the detection of the measurement physical quantity. This sensor has the advantages of simple structure, controllable mode excitation, high sensitivity, no-cross sensitivities and so on, which opens up a new way for the research and application of the special fiber optic sensor. Thus, it is of great significance to carry out the relevant theoretical and experimental research around its characteristics.In this paper, the cladding mode resonance phenomenon of the triple cladding quartz specialty fiber(TCQSF) and the characteristics of this sensor have been analyzed specifically based on coupled mode theory. The concrete contents include:Firstly, the background and the significance of the research is introduced. The domestic and international research status of the mode coupling optical fiber sensor are analyzed by introducing its preparation methods and sensing principle. The research contents and innovation of this article are proposed.Then, the normal mode theory and the coupled mode theory, which are used to analyze multi-cladding fiber, are introduced. Utilizing the coupled mode theory, the effective model of the TCQSF is established. The mode field distribution, characteristic equation and dispersion curves of this model are calculated and obtained, also the relationship between the length and transmission spectrum of the sensor is established.Next, a straight forward experiment is performed to study the temperature sensing properties of this cladding mode resonance sensor. With the temperature increasing, the changes of TCQSF structure parameters are analyzed based on the thermal-optic effect and thermal expansion effect. The relationship between different temperature and wavelength drift is studied experimentally.Once more, the curvature sensing characteristics of this sensor is studied. The field distribution of each mode in TCQSF under different curvature conditions is analyz ed. The relationship between different curvature and wavelength drift is studied experimentally.Finally, the characteristics of the sensor based on TCQSF which is dislocation welding with the single mode fibers is studied. The relationship between the size of the dislocation and refractive index sensitivity is analyzed. The refractive index and temperature characteristics of the sensor are tested and discussed.