论文部分内容阅读
利用长周期光纤光栅(LPFG)的双峰谐振效应,结合LPFG传感器工作于近相位匹配转折点(PMTP)附近的高灵敏度,提出了一种新型的长周期光纤光栅应变传感器的设计方法。利用LPFG相位匹配条件,分析了长周期光纤光栅近PMTP附近的双峰谐振特性、应变传感特性,发现双峰波长间距对微小应变具有很高的响应度和线性度。进一步讨论了光栅结构参数和包层直径对双峰LPFG应变灵敏度的影响,发现光栅周期对该传感器的应变灵敏度、线性度和应变测量范围具有很大的影响;光栅长度对谐振峰高度和宽度有较大影响,直接关系到传感器寻峰精度;通过增大包层直径,可以进一步增大应变灵敏度。结果表明,通过选取适合的光栅结构参量和包层半径,该传感器应变灵敏度可比一般长周期光纤光栅应变传感器的应变灵敏度提高2个数量级。这为设计高应变灵敏度双峰谐振LPFG应变传感器提供了结构优化的理论支持。
Based on the bimodal resonance effect of long period fiber grating (LPFG) and the high sensitivity of LPFG sensor operating near the PMTP, a novel design method of long period fiber grating strain sensor is proposed. Based on LPFG phase matching condition, the bimodal resonance and strain sensing characteristics near PMTP of long period fiber grating are analyzed. It is found that the bimodal wavelength spacing has high responsivity and linearity to the micro strain. The effects of grating structure parameters and cladding diameter on the bimodal LPFG strain sensitivity are discussed. The grating period has a great influence on the strain sensitivity, linearity and strain measurement range of the sensor. The grating length has a significant influence on the resonant peak height and width A greater impact, is directly related to the peak-seeking accuracy of the sensor; by increasing the cladding diameter, you can further increase the strain sensitivity. The results show that the strain sensitivity of this sensor can be increased by 2 orders of magnitude compared with the strain sensitivity of a general long-period FBG strain sensor by selecting suitable grating structure parameters and cladding radius. This provides structural optimization of theoretical support for designing bimodal resonant LPFG strain sensors with high strain sensitivity.