摘要
提出并研制了一种结构简单、成本低廉的全光纤型高温-应变组合传感器,其结构是在具有微气泡腔的在线型Fabry-Perot干涉仪(FPI)后级联一个高频CO2激光脉冲写入的长周期光纤光栅(LPFG)。FPI通过采用商用化的熔接机熔接普通单模光纤(SMF)和多模光子晶体光纤(MPCF)形成,两类光纤间的空气泡形成FP干涉腔,由于MPCF具有较大的数值孔径并且其包层具有较大的空气孔,所以MPCF-FPI的干涉条纹具有较大的信噪比和对比度;并且,光纤的表面张力使气泡腔的表面足够光滑,不会降低熔接点的极限强度,从而确保了FPI是一种理想的耐高温应变传感器。高频CO2激光脉冲写入的LPFG能耐800℃高温,且具有较高的温度敏感性。通过分别监测MPCF-FPI和LPFG的波长漂移量,实现应变-高温的同时测量。实验结果表明,本文研制的传感器,其应变灵敏度为2.7 pm/με,温度灵敏度为0.07 nm/℃,可满足实际应用的要求。
An optical fiber high-temperature strain sensor is proposed and fabricated which is formed by combining an in-line photonic crystal fiber Fabry-Perot interferometer（FPI） with an air bubble cavity and a long-period fiber grating（LPFG） written in a standard single mode fiber using high-frequency CO2 laser.The in-line FPI was constructed by directly splicing a mutimode photonic crystal fiber（MPCF） to a conventional single mode fiber with a commercial splicer.The air microbubble inserted between the two fibers has two smooth glass-air interfaces separated by a distance L as two reflective mirrors of the FPI.Due to big air holes in the cladding of MPCF and its large numerical aperture,this device has higher signal-to-noise ratio and fringe contrast.In addition,the bubble usually does not reduce the ultimate strength of a fusion splice,the since surface tension ensures that they have smooth walls which do not serve as stress concentrations or crack nucleation sites,so such a FPI can be used as an ideal strain sensor under high temperatures.The LPFG written by high-frequency CO2 laser can survive high temperatures up to 800 ℃ and has relatively high temperature sensitivity.Therefore,simultaneous measurements of high-temperature and strain can be realized by monitoring the wavelength shifts of the FPI and LPFG.The experimental results show that this method has strain sensitivity of 2.7 pm/με and temperature sensitivity of 0.07 nm/℃,meeting the requirements for practical applications.
出处
《光电子．激光》
EI
CAS
CSCD
北大核心
2011年第7期1067-1071,共5页
Journal of Optoelectronics·Laser
基金
国家科技重大专项资助项目(2008ZX05041-008)
中央高校基本科研业务费资助项目(CDJZR10120002)
