基于粗锥结构级联LPFG的双包层光纤多参量传感器

Multi-parameter Sensor Based on Waist-enlarged Taper with Double Cladding Fiber Cascade LPFG

提出了一种基于模间干涉的测量温度、折射率和轴向应变的光纤传感器.在单模光纤与双包层光纤熔接点处形成粗锥,再与两个周期不同的长周期光纤光栅级联,由于模场失配,激发高阶模,形成三个谐振峰,且对不同参量有不同的灵敏度响应,通过解调三个谐振峰的波长漂移,利用系数灵敏度矩阵,可以测量温度、折射率和轴向应变.实验结果表明,温度在25℃~75℃范围内,灵敏度分别为60.07 pm/℃,6.47 pm/℃和103.83 pm/℃;折射率在1.3355~1.3595范围内,灵敏度分别为−56.64 nm/RIU,34.02 nm/RIU和−214.84 nm/RIU;轴向应变在200με~1400με范围内,灵敏度分别为−2.14 pm/με,−3.61 pm/με和−2.59 pm/με,且分辨率分别为1.29℃、0.00042 RIU和21.42με.该传感器具有灵敏度高、线性度良好等优点,可广泛应用于多参量测量领域。

A optical fiber sensor based on modular interference is proposed to measure temperature,refractive index and axial strain.Waist-enlarged taper is formed at the splice point of a single-mode fiber and a double-cladding fiber,which is then cascaded with two long-period fiber gratings with different periods.Due to the mismatch of the mode fields,the higher-order cladding modes are excited,three resonance peaks are formed,which have different sensitivity responses to different parameters.Therefore,by demodulating the wavelength shift of the three resonance peaks and using the coefficient sensitivity matrix,temperature,refractive index and axial strain can be measured.The experimental results show that the sensitivity is 60.07 pm/℃,6.47 pm/℃and 103.83 pm/℃in the temperature range of 25℃~75℃,the refractive index is in the range of 1.3355~1.3595,and the sensitivity is-56.64 nm/RIU,34.02 nm/RIU and−214.84nm/RIU,the axial strain is in the range of 200~1400με,the sensitivity is−2.14 pm/με,−3.61 pm/μεand−2.59 pm/με.The resolution is 1.29℃,0.00042 RIU and 21.42μεrespectively.The sensor has high sensitivity,good linearity and other advantages,can be widely used in the field of multiparameter measurement.