Study On Photonic Crystal Fiber Mach-zehnder Interometer Based On Waist-enlarged Technology

Due to obvious advantages of compact structure,anti-electromagnetic interference,easy fabrication,high sensitivity and others,the optical fiber sensors have been widely used in machinery,bridge,architectural structure and health monitor at bending deformation of high precision instruments and equipment.Because of the photonic crystal fiber(PCF)structure has flexible design,that makes it have many peculiar features,and become a hot research topic in the field of optical fiber sensing.Based on theory of Mach-Zehnder interferometer,the method of excessive fusion splicing,core-offset splicing to prepare Mach-Zehnder interferometer and optical sensing properties are studied.The curvature and strain sensing properties of waist-enlarged PCF taper sensor are studied in detail.The main research contents are as follows:Firstly,fiber interferometric sensor,curvature and strain sensors are introduced in research.Based on the analysis of the basic theory of Mach-Zehnder interferometer and the photonic crystal structure used in the experiment,the transmission mode,output interference spectrum and other results were simulated,then the relationship between the different modes of interference and the length of the different sensing zones and the transmission spectra is established;Secondly,the preparation method and the sensing characteristics of the direct splicing and waist-enlarged PCF taper sensor are studied.The experiment analyzed curvature and strain sensing characteristics of different sensing zones and the different wavelengths of the same sensor;Thirdly,the sensing characteristics of core-offset splicing and waist-enlarged PCF taper sensor are studied.The effects of different splicing misalignment and PCF length on the curvature and strain sensing properties of the sensor are studied experimentally;Finally,the method and the sensing characteristics of corroded and waist-enlarged PCF taper sensor are studied.The influence of different fiber diameters on the curvature and strain sensing properties of the sensor are analyzed in the experiment.