Research On Optical Fiber Sensor Based On Down-Taper Shape Structure

Optical fiber sensor based on down-taper shape fusion structure is mainly investigated in this thesis.Three kinds of relative fiber sensor is designed in the thesis mainly designs.The first sensor is constructed by a down-taper and a peanut shape structure,the second optical fiber sensor based on a down-taper structure spliced with a long-period fiber grating,the third optical fiber sensor is made by a Down-taper—multimode fiber-peanut structure.Using three fiber sensors to analysis their performance in physical quantities experiments.The main work of this thesis is as follows:1.The typical fiber structures based on different fiber interferometer are introduced.The modal interference theories of M-Z interferometer are mainly stated,and the manufacture process of the down-taper structure is introduced.The energy distribution in fiber core was simulated by Rsoft when the light goes through the down-taper with different diameter.2.An optical fiber cascade sensor based on peanut shape structure and down-taper structure is proposed.The background and measuring principle of the liquid level,refractive index are introduced,respectively.Experiments are carried out for the measurement of these two parameters with the sensor of different length.According to the experimental results,study and analysis are done to this sensor.3.A fiber sensor based on a down-taper shape structure spliced with long-period fiber grating(LPG)is proposed,the length of the LPG is 40 mm,and there is a 10 mm single mode fiber between the down-taper shape structure and the LPG,so the entire length of this sensor is 50 mm.Introduction of some basic measuring principle of the curvature and temperature are done and carried out two physical experiments with the sensor.With these two experiments,the corresponding sensitivity is brought into the sensitivity matrix to achieve simultaneous measurement of curvature and temperature.4.A fiber sensor based on a down-taper-multimode fiber-peanut shapestructure is proposed.The transmittance spectra obtained from these fiber sensors with different lengths are discussed.Experimental studies were carried out to study the effects of different lengths on curvature and temperature.