Temperature Characteristics Of Embedded Twin-core Hollow Optical Fiber Sensors

Embedded twin-core hollow fiber is a kind of special type fiber with special geometrical structure,the theory and experiment research about the shape changing of this fiber have been demonstrated in this article.In order to use this fiber to fabricate high sensitivity optical fiber temperature sensors,we have fabricated M-Z interferometer and LPFG based on this fiber and conducted a series of theory and experiment researches at the same time.As fellows are some specific works:We set up finite-element models of embedded twin-core hollow fiber which can be used to make the theory analysis in thermal tapering process,and analyzed fiber's strain characters by stimulating fiber's thermal tapering process through ANSYS.We got the graph curves with different pulling speed.We analyzed the theoretical process of fiber's thermal collapse,and stimulated the whole process through ANSYS,then we obtained fiber's collapsed deformation at different heating parameters and analyzed the influences of collapsed deformation caused by heating temperature and heating time.We made the image processing for end surface of embedded twin-core hollow fiber and measured geometry size at end surface of fiber.We fabricated M-Z interferometer and researched impacts of transmission spectrum at different bend extends.Then we experimented temperature characters of our fabricated interferometer and the results indicate that: peak wavelength will move to short wavelength direction with increase of temperature;different wavelength has different temperature sensitivities and the temperature sensitivity increases with the increase of wavelength.We built a platform for LPFG's fabricating and fabricated some LPFGs in different parameter with method of heating collapse.We researched the impacts of LPFG's transmission spectrum at the changes of different fabrication parameters.In the end we made series of theory analysis and experimented LPFG's temperature characters,the results indicate:LPFG's resonance peak wavelength will move to long wavelength directions with the increase of temperature,and it has the same characters at both warming and cooling process,LPFG owns a good heating stability and its temperature sensitivity is 33pm/?.In summary,the two fiber sensors which fabricated by embedded twin-core hollow fiberhave a higher temperature sensitivity.