Research On Vibration Sensors Based On Optical Fiber And Waveguide

In recent years, with frequent outbreaks of earthquakes, continuous explorationon ocean sonar detection and prospecting for oil, etc, the vibration sensors quicklybecome a hot research worldwide, especially fiber and waveguide vibration sensor.Because of the fiber’s unique advantages, in the study on ocean detection andmechanical vibration, optical fiber and optical waveguide vibration sensors havebeen widely used.Fiber and waveguide vibration sensors, especially sensors of cantilever,micro-cantilever, conical structured detectors, which has become more integratedand cheap, have a bright future. In this paper we focus our attention on figuring outfrequency response feature of cantilever fiber and waveguide stimulated by soundwave.In this paper, the fabrication methods of cantilever, micro-cantilever andconical structured fiber are studied. And some experiments have been done aboutmicro-cantilever beam and tapered fiber processing, which find out the parameters,such as transmission power and scan speed of femtosecond laser, as well as thetransmission power of CO2laser when tapering the fiber. An1.67mW laser outputpower and a scan speed of160μm/s would be fine when curving the cantileverstructure in the fiber, while in the waveguide, the output power should be about2.68mW and speed should be limited between160μm/s and200μm/s.In this paper, firstly, we analyze the vibration characteristics of a cantileverbeam. Then analyze the modal of tapered optical fiber and cantilever of differentsize with finite element analysis software PATRAN to figure out the first three ordervibration mode function and the inherent vibration frequency. We take the first-ordervibration frequency values as our experimental reference value, and discuss thetransfer mode of tapered fiber.In the experiment, we use the single frequency audio signal as the stimulus,stimulate cantilever beam of different structures and different sizes. We useLABVIEW to do real-time monitoring, and program in MATLAB to do dataacquisition and analysis. Finally we draw the resonance peak and spectral responserange which means we can draw desired spectral range by designing appropriatecantilever structure.