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Research On Sensing Properties And Key Preparation Techniques Of Material-filled Or Film-covered Photonic Crystal Fibers

Posted on:2019-02-18Degree:DoctorType:Dissertation
Country:ChinaCandidate:G W AnFull Text:PDF
GTID:1488306338979789Subject:Detection Technology and Automation
Abstract/Summary:PDF Full Text Request
Due to its flexible structure design and excellent optical performance,photonic crystal fiber(PCF)is one of the research hotspots in the field of new photoelectric devices.Optical fiber sensing has the advantages of anti-electromagnetic interference,high sensitivity,good insulation,and can realize distributed measurement.The porous properties of photonic crystal fibers are beneficial to expand or enhance their performance by filling photoelectric functional materials.The D-shaped and coating treatment of photonic crystal fiber will help to enhance the coupling between the evanescent field and the measured analytes.Due to the special structure of photonic crystal fiber,the difficulty of fabrication technology has been restricting the development of photonic crystal fiber in sensing field.In this paper,the sensing characteristics of material-filled and film-covered photonic crystal fibers are studied numerically,and the preparation and filling processes of photonic crystal fibers are experimentally studied.The photonic crystal fibers prepared in the laboratory are also detected.The main work is as follows:1.The background and development history of photonic crystal fiber are introduced,and the sensing principle and application method in sensing field are described.The wave theory and numerical simulation method of electromagnetic wave transmission in photonic crystal fiber are given systematically.The application and advantages of finite element method in the design of photonic crystal fiber are emphatically analyzed,and the preparation technology of photonic crystal fiber at home and abroad is described in detail.2.The sensing mechanism of photonic crystal fiber refractive index sensor with a rectangular lattice structure is analyzed by means of mode control and coupling theory.A dual-core photonic crystal fiber refractive index sensor with a rectangular cladding lattice array is proposed based on the periodic coupling effect of the core energy of dual-core photonic crystal fiber.According to the high birefringence effect of rectangular lattice single core photonic crystal fiber,a Sagnac interferometric-based refractive index sensor is proposed.The advantages of photonic crystal fiber with rectangular lattice cladding in the sensing field are further analyzed:Compared with the triangular lattice,the photonic crystal fiber with rectangular lattice is more conducive to the diffusion of the core energy because of its lower binding capacity to the core conduction mode.Therefore,the ability to perceive external refractive index changes is stronger and sensor sensitivity is higher.3.Several Au film coated D-shaped and quasi-D-shaped photonic crystal fiber refractive index sensors that do not need to be filled with analytes are proposed based on the surface plasmon resonance theory.The refractive index sensing characteristics can be controlled by the coupling effect between the core mode and the SPP mode.The numerical results show that in the case of the cladding structure with the same hole pitch and air filling factor,the double-channel sensing can be better realized when the cladding air holes are of a rectangular lattice structure or photonic crystal fibers whose sensing region are designed with quasi-rectangular lattices and this type of sensor has a higher sensitivity than the fibers with a triangular lattice structure.4.The photonic crystal fiber preparation experiment was systematically carried out,several key parts of the optical fiber drawing tower were improved,and the process parameters of photonic crystal fiber preparation were optimized.The relationship among the furnace temperature,sending speed and traction speed and its influence on the effect of the formed fiber are analyzed.During the preparation process,two major technical problems were discovered and solved:(1)Concentricity of optical fiber coatings.The method of using the red laser beam to interfere is proposed to solve the problem of low concentricity of fiber coating layer which is caused by the high traction speed and the insufficient degree of alignment of the drawing tower.The experimental results show that the change of coating thickness in the range of ±5?m can be detected successfully by this method,and the concentricity of the coating can be corrected by means of fine-tuning the mould and changing feed volume.(2)A set of maintenance device which can achieve controllable cladding structure and pressure adjustable effect has been designed and manufactured.By designing the control and feedback system and selecting the appropriate micro-pressure control solenoid valve and controller,the collapse rate of the cladding cores during the preparation of the photonic crystal fiber can be greatly reduced.The fabrication of Ag filled photonic crystal fiber is preliminarily carried out and its femtosecond laser transmission characteristics are tested.5.The transmission spectrum of the photonic crystal fiber was measured according to the Mach-Zehnder(M-Z)interferometry.The photonic crystal fiber with a length of 5cm is welded by single-mode optical fiber.By appropriately adjusting the arcing parameters of the fusion splicer,the degree of collapse of the weld zone can be controlled,so that the energy of the cladding mode can be transmitted and can interfere with the core conduction mode in the terminal.The experimental results show that the sensor exhibits highly RI sensitivity which is found to be 326nm/RIU.It also proves that our photonic crystal fiber can be applied to the refractive index sensing and detection field.
Keywords/Search Tags:Photonic crystal fiber, Material filling or coating, Pressure controllable device, Surface plasmons, Refractive index sensor, Interferometric sensor
PDF Full Text Request
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