편광유지 광자결정 광섬유를 이용한 편광 간섭형 진동 센서에 관한 연구

Abstract

In this thesis, a polarimetric optical fiber vibration sensor was implemented by incorporating a Sagnac birefringence interferometer composed of polarization-maintaining photonic crystal fiber (PM-PCF). A 8-cm-long thread of PM-PCF was used as the sensor head of the proposed sensor, and the sensor response to various types of vibration was investigated. In order to investigate the vibration response of the proposed sensor for single-frequency vibration, a vibration with a fixed frequency was applied to the sensor head by using a cylindrical piezoelectric transducer. In the case of the single-frequency vibration measurement, the sensor response was investigated for a frequency range of 1-8000 Hz. The proposed sensor allowed the detection of vibration, of which amplitude corresponded to an effective static strain of ~6.75 με(rms) over a single-frequency vibration range of 1-5000 Hz. It was observed that the sensor response started to deteriorate from 5000 Hz in the single-frequency vibration measurement, and then the sensor response to naturally damped vibration was also examined by utilizing a metal cantilever beam and a few weights. It is found from the examination that the sensor response is related with initially applied stress in the naturally damped vibration measurement.