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Study Of High Quality Subwavelength Microfiber Fabrication Process And Microknot Gas Sensing Property

Posted on:2014-02-19Degree:MasterType:Thesis
Country:ChinaCandidate:W Q YiFull Text:PDF
GTID:2268330401965427Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Optical fiber is the most important media for modern communication system andoptical fiber sensing technology. With the development of modern technology, there isan increasingly demand for miniature photonic devices based on optical fiber.Microfiber is a recently appeared novel micro-structure, its outstanding characters suchas compact size, low loss and that a large proportion of light transmitted outside thefiber core as evanescent waves, have made it one of the promising fields in fiberoptical sensing. How to conveniently manufacture high-quality microfibers at low costand apply them to the most challenging gas sensing field remain problems for allresearchers at home and abroad.This article firstly summarized various manufacture processes of the microfiber aswell as its applications in different fields, and then elaborated on the microfiber knotresonator, a photonic device made of microfiber, according to its classification. Thebasic transmission theory of microfibers was introduced as well as its manufactureprocess using alcohol flame brush method. To overcome the shortcomings of themanufacture method mentioned above, a new drawing method of motorized translationstage was adopted, and successfully obtained microfibers of different sizes withuniformed diameters and good surface quality in the experiments.Furthermore, the optical light transmission theory of microfiber knot resonatorswas derivated and adopted Matlab software to simulate its light transmission charactersand discussed several factors which could have severe impact on the output field of thestructure. Then present one of microfiber’s characters that a large proportion ofevanescent field propagating outside the fiber could feel the external refractive indexchange and lead to the transmission peak drift, this phenomenon could find itsapplication in gas sensing. After detailed description of the microfiber knot resonatormanufacture method adopted before, putting forward a new fabrication method thedouble tapered drawing method. This new way could improve the extinction ratio from5dB to10dB as well as the Q factor because of the optimization of the structure’soptical coupling efficiency and resulted in the upgrade of its detection resolution. Tested new microfiber knot resonator’s gas sensing property by free volatilization ofchemical liquid in confined space, its sensitivity for acetone is115.3nm/(mol/L) and52.3nm/(mol/L) for ammonia water, and the corresponding resonant peak drift isproportional to the concentration of the volatile organic compounds.Finally, from the basic principle of Mach-Zehnder interferometer, we brieflydiscussed several kinds of fiber Mach-Zehnder interferometer system and elaboratedthe principle and manufacture methods for them, then adopted Matlab software tosimulate its transmission characteristics. Based on the work described above, a hybridstructure of micro fiber knot resonator and Mach-Zehnder interferometer was proposed,and its transmission characteristics were theoretical and experimental studied, thisstructure can realize multi-parameter monitoring, improve the extinction ratio and actas a refractive index sensor as well.
Keywords/Search Tags:Micro-nano fiber, fiber knot resonator, fiber drawing system, gas sensing, Mach-Zehnder interferometer
PDF Full Text Request
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