Research On Sensing Theory And Technology For Liquid Core Microstructured Fiber

The flexibility of air hole structure design of microstructured fiber brings more optical performance advantages compared with traditional fibers,making it shine in the field of fiber sensing.Owing to the action of photonic bandgap effect,most part of the transmission light energy is limited in the central large air hole,which induces a greatly stronger interaction of the material filled in central hole and the light propagation in the same the central hole,thus leads more potential applications in the field of high sensitive sensors,optical fiber fluorescence sensing,light amplifier,Raman spectroscopy and other fields.Based on the summary of microstructured fiber sensor research status at home and abroad,an alcohol liquid sample of a large thermo-optic coefficient and a magnetic fluid of an effective magneto-optic coefficient are filled into the central air-hole to interact with the high intensity light in the same central hole of microstructured fiber to analyze the temperature sensitivity and magnetic field sensitivity theoretically and experimentally respectively.The main research contents of this paper are as following.Firstly,the optical property(propagating modes and corresponding mode dispersion property)is numerically analyzed for microstructured fiber with central air hole filled with temperature sensing material.The influence factors of interference spectrum are discussed based on the sensing principle of mode interference sensor,and optical fiber length,optical wavelength and thermo-optical coefficient of filling material on the sensitivity performance of the sensor are summarized.The theoretical temperature sensing performance of microstructured fiber with the central air hole filled with alcohol is completed.Secondly,three methods to collapse the cladding holes of microstructured fibers by fusion splicer are proposed,and the optimal technique is selected for the sensing fiber fabrication.Alcohol is selectively filled into the central hole of microstructured fiber to fabricate the temperature sensor to conduct the experiment,and the performance of the sensor is analyzed.Thirdly,the microstructured fiber temperature sensor without filling any material is prepared.Its structure is the same as that of the alcohol-filled central air hole sensor,which is used to explore the response characteristics of the fiber itself to temperature.The temperature measurement experiment of the sensor is also conducted,and the results are analyzed and compared with the temperature response of microstuctured fiber with central air hole filled with alcohol.Then,numerical simulation is conducted to analyze the propagating modes and mode dispersion characteristics when the magnetic fluid is filled in the central air hole of the microstructured fiber.The influence factor on the sensitivity is discussed and the responding magnetic field sensitivity is predicted in theory.Finally,the magnetic field generator is prepared by using the solenoid.After the fiber is pre-collapsed by the fusion splicer,the magnetic fluid is filled in the central air hole of the microstructured fiber to measure the magnetic field intensity,and the magnetic field sensing performance of the structure is analyzed.