基于温度自补偿的光子晶体光纤光栅的应变传感特性研究

Strain sensing characteristics of photonic crystal fiber Bragg grating based on temperature self-compensation

在正六边形包层空气孔中填充特定负折射率温度系数材料,通过温度自补偿实现非温度依赖的应变传感检测。基于耦合模理论,建立传感分析模型,结合控制变量法对不同温度和波长下的模式有效折射率进行数值分析。在包层空气孔填充不同液体材料,探究基模以及一阶光波模式的谐振波长对温度的不敏感特性,并对PCFBG中不同光波模式的温度/应变传感特性进行对比研究。计算结果表明,在包层空气孔填充材料I,环境温度由-20℃升至100℃,基模光场的反射峰中心波长仅漂移2.3pm,应变灵敏度达到1.234 8pm/με;在包层空气孔填充材料II,一阶光波模式仅漂移4.6pm,应变灵敏度为1.311 8pm/με。表明在光子晶体光纤包层空气孔中填充对应的温度补偿材料能有效实现具备温度稳定性的高灵敏度应变传感监测。

A temperature self-compensating strain sensor is demonstrated by filling specific material with negative temperature coefficient of refractive index in the cladding air holes of hexagonal photonic crystal fiber Bragg grating（PCFBG）.Based on coupled mode theory,we establish theoretical analysis model.And then,combined with control variable method,we make an numerical analysis about the change of effective refractive index in different temperatures and wavelengths.Through inserting different liquid materials in the cladding air holes,we find that the resonance wavelength of fundamental mode or the firstorder optical mode cannot be sensitive to the temperature.On the basis of that,we study temperature and strain sensitivity sensing properties of different modes in PCFBG.The experimental results show that when the environment temperature is increased from-20℃to 100℃,the reflection spectra of fundamental mode drift 2.3pm and the sensitivity of strain is up to 1.234 8pm/μεwhen filling material I in the cladding air holes;those of the first-order mode drift 4.6pm and the sensitivity of strain is up to1.311 8pm/μεwhen filling material II in the cladding air holes.As a result,it can achieve temperature insensitive strain measurement when to specific material with negative temperature coefficients refractive index is filled in the cladding air holes of photonic crystal fiber.