Research Of Fiber Sensor Based On Spherical-shape Fusion Splicing

Recent years,M-Z fiber sensor has become research hotspot because of the characteristic of small size,strong mechanical structure,and high sensitivity.The work of this thesis is to study the theory,fabrication,and application of M-Z fiber sensor based on spherical-shape structure,cascade the spherical-shape structure with other fiber structures to fabricate new sensor,and research on their performance in physical quantities experiments to testify their prospects in different applications.The specific contents of the paper are as follows:1.An M-Z fiber optic sensor with single mode fiber and spherical-shape structures is proposed.The theory and production method of the spherical-shape structure are introduced.The energy simulation of the fiber core when light propagate through the spherical-structure is performed by Rsoft software,and the spatial spectrum of the transmission spectrum is analyzed by fast Fourier transform.The liquid level experiments are performed and outcomes are analyzed,and the effect of changing the refractive index and the length of the sensor are also discussed.2.A fiber sensor based on SMS structure and spherical-shape structure for refractive index testing is fabricated.The SMS structure,which is composed of a short piece of MMF,can excited high order cladding modes,the cladding modes will interference with the core mode at the spherical-shape.Refractive index experiment and temperature experiment are operated and the temperature-refractive-index cross sensitivity is studied.3.We also proposed an M-Z optical fiber sensor based on core-offset and spherical-shape structure.The simulation of the energy in the fiber core at different offset value is performed and the outcomes have been fitted into curves.Two lengths of the sensor was fabricated,two dips of each sensor's spectrum are selected in order to monitor the wavelength shift.After the curvature and temperature experiment,sensitivity matrix is introduced to calculate the variations of curvature and temperature by substuting the sensitivities into the matrix,thus simultaneous measurement can be achieved.