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A chemical sensor based on surface plasmon resonance on surface-modified optical fibers

Posted on:1994-09-17Degree:Ph.DType:Dissertation
University:Virginia Polytechnic Institute and State UniversityCandidate:Bender, William John HavercampFull Text:PDF
GTID:1478390014492312Subject:Chemistry
Abstract/Summary:
A sensor is described which utilizes the phenomenon of surface plasmon resonance to detect changes in refractive index of chemical or biochemical samples applied to a surface modified optical fiber.; The sensor is constructed by polishing a short section of the lateral surface of an optical fiber to its evanescent field surrounding the fiber core. One or more thin films are applied to the polished section of the fiber to produce the sensing element. One of the films is the metal silver, which acts as the support for the surface plasmon.; Under the proper conditions, TM polarized energy propagating in the fiber can be coupled to a surface plasmon electromagnetic mode on the metal film. This coupling depends on the wavelength, the nature of the fiber, the refractive index and thickness of the thin films applied to the fiber, and the refractive index of a chemical sample in contact with the modified surface. The fiber to plasmon coupling is seen as a large attenuation of the light reaching the distal terminus of the fiber.; A dispersion equation is derived which predicts the conditions necessary to achieve resonance on both the three layer (fiber/metal/chemical sample) and four layer (fiber/metal/overlay/sample) geometries. Details of sensor construction and instrumental design are given, along with experiments which illustrate the feasibility of SPR generation on an optical fiber and verify the predicting power of the dispersion equations. A comparison is given between the fiber-based instrument and classical prism-based SPR devices.; Several possible future improvements and applications of the device are given, along with possible sensor and instrumental configurations.
Keywords/Search Tags:Sensor, Surface plasmon, Fiber, Chemical, Resonance, Refractive index
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