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Theoretical Research On Biosensing Based On Dual-Mode Microstructure Fiber Laser

Posted on:2014-10-30Degree:MasterType:Thesis
Country:ChinaCandidate:X Q GaoFull Text:PDF
GTID:2268330392964597Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Biosensors will not only promote biological technology by leaps and bounds, but also play an increasingly important role in many applications inculding health care, biomedical research, environment monitoring, homeland security and national defense construction. In this paper, the microstructured optical fiber provides the microfluidic channel for analyte. In order to form dual-mode laser resonant cavity, the long-period grating and fiber Bragg grating are cascaded in the microstructured optical fiber, whose facet is coated with metal. This transducer is based on perturbation of the simultaneous lasing of the core mode and a high-order cladding mode which is inflected by the analyte refractive index. The details are described as follows:Firstly, the basic idea and analyzing process of finite element method are discussed in detail. Meanwhile, this research focuses on the coupling mode theory about the index modulation fiber gratings and the coupled local-mode theory about structural change long period fiber gratings.Secondly, the theory of microstructured fiber gratings written through the refractive index modulation are described based on the modal properties of the microstructured optical fibers and coupled mode theory of fiber gratings. The mode couplings of long period microstructured fiber gratings written through the structural change are discussed with the coupled local-mode theory, and the simulations of transmission spectra are achieved. Based on the above methods, the transmission characteristics and mode couplings of various microstructured fiber gratings can be explained.Thirdly, a simplified model of equivalent refractive index biofilm is established to study the refractive index sensing properties of microstructured fiber gratings. The relationships between the resonance wavelength of fiber Bragg grating and the refractive index are obtained. The refractive index sensitivity of long period grating is achieved by numerical simulation, and the relationships between refractive index sensitivity and different fiber grating parameters are obtained. In addition, the refractive index sensitivity of the structural change long period grating is studied. Finally, using the fiber Bragg grating and long period fiber grating inscribed in micro structured optical fiber with the other active devices, the dual mode laser output is realized through the continuous optimization of each device parameter, then the feasibility of the biosensing system is theoretically proved.
Keywords/Search Tags:biosensor, fiber laser, microstruetured optical fiber, fiber Bragg grating, long period grating
PDF Full Text Request
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