Gas refractometry using hollow core photonic bandgap fiber

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.advisor Shavrin, Igor Parameswaran Iyer, Siddharth 2015-04-22T12:04:12Z 2015-04-22T12:04:12Z 2015-03-30
dc.description.abstract Over the last two decades, much research has been carried out on sensors based on photonic crystal fibers. Their unique structure comprising of a periodic array of air holes running along their length provides optical properties that are highly suited for refractometer sensors. The thesis presents a fiber-optic interferometric gas refractometer which is capable of spectrally resolved measurements of both real and imaginary parts of the complex refractive index. The refractometer is based on an earlier fiber based Mach-Zehnder-type refractometer design that was used to determine the refractive index of air-acetylene mixture. The aim of the thesis was to improve the device design in order to ascertain the refractive index of pure acetylene. The device adopts a hollow-core photonic bandgap fiber as both a sample cell and a waveguide. This provides the best overlap between probing light and the analyte. In addition, it requires a very small volume of the analyte due to the small dimensions of the fiber, and the sample cell can be made long while keeping the device compact. The complex refractive index of approx. 96 percent pure acetylene was measured within the optical C band where the gas has a number of pronounced resonance frequencies. The measurement was repeated in approx. 500 Pa air and was used as reference for interpreting the results for acetylene. The optical absorption and refractive index change of acetylene over the resonance frequencies were analyzed and its absorption coefficient and refractive index were calculated. The demonstrated capability of this device to measure the real and imaginary parts of the refractive index of an analyte has important implications in the sensor industry. en
dc.format.extent 48 + 6
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.title Gas refractometry using hollow core photonic bandgap fiber en
dc.type G2 Pro gradu, diplomityö en Sähkötekniikan korkeakoulu fi
dc.subject.keyword gas refractometer en
dc.subject.keyword hollow core photonic bandgap fiber en
dc.subject.keyword Mach-Zehnder interferometer en
dc.subject.keyword complex refractive index en
dc.subject.keyword fiber sensor en
dc.identifier.urn URN:NBN:fi:aalto-201504232419
dc.programme.major Optoelectronics and Photonics fi
dc.programme.mcode ELEC004Z fi
dc.type.ontasot Master's thesis en
dc.type.ontasot Diplomityö fi
dc.contributor.supervisor Ludvigsen, Hanne
dc.programme EST - Master’s Programme in Micro and Nanotechnology fi
dc.location P1 fi

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