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Research On The Sensing Properties Of Integrated Interferometer Based On Multimode Fiber

Posted on:2015-06-14Degree:MasterType:Thesis
Country:ChinaCandidate:Y Y YangFull Text:PDF
GTID:2348330518472225Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Optical fiber sensing is the important research field of fiber optics. Compared with the traditional sensors, the optical fiber sensor has high sensitivity, anti-electromagnetic interference, corrosion resistance and other advantages which can achieve the goals that traditional sensor can't. Michelson and Mach-Zehnder optical fiber sensor are two commonly used types. However, their industrial production is difficult, because they recommend high requirements in two fiber lengths and the external environment due to the dual optical path structure. The emergence of special fiber makes the two arms structure interferometer can be integrated into one fiber, which increases the degree of integration and makes its application more widely. Then, the sensor based on modal interference with simpler structure and stronger anti-interference is presented. Modal interference sensor can be established by tapering, core offset splicing, core diameter mismatch and other methods.In the paper, we proposed the SMSMS-based Mach-Zehnder interferometer and SMS-based Michelson interferometer using the multimode fiber (MMF) and conventional single-mode fiber (SMF) due to the large mode mismatch. For both of the structure, the sensing element is the SMF. For the SMSMS structure, the SMF between the two MMFs servers as the sensing element whose coating is stripped away, while for the SMS strcture, the sensing element is a section of SMF which is fusion spliced after the MMF and its coating is tripped away. Firstly, we use the Beamprop Software for simulation: simulate the mode field distribution in the multimode fiber, and simulate and analyze that the cladding mode distribution in the SMF which is excited by the different length of MMF when the multimode fiber is coupled with the single mode fiber. Secondly, we produce the SMSMS-based Mach-Zehnder interferometer and SMS-based Michelson interferometer; measure the transmission spectrum of the two kinds of interferometer with different lengths of the MMF,and do the Fast Fourier Transform (FFT) to obtain the spatial spectrum of them; analyze the temperature and refractive index (RI) sensing properties of the interferometer; build the experimental set up,and do a lots experiments on the temperature and RI properties to obtain the different response of different MMF length on temperature and RI sensitivity. From the experimental results, it can be seen that the both structure are of good temperature sensitivity and the RI corresponding response of the interferometer with different MMF length is inconsistent, moreover, it can be seen that the sign of the sensitivity is inversed.
Keywords/Search Tags:optical fiber sensor, multimode fiber, optical fiber modal interferometer, SMSMS, temperature and refractive index
PDF Full Text Request
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