保偏光纤转轴熔接Sagnac干涉环的光学游标效应及温度传感器

Vernier effect based on optical fiber Sagnac interference loop with two angle shift spliced polarization maintaining fibers and its application on temperature sensor

为了实现高灵敏度的温度传感,通过在基于保偏光纤Sagnac干涉仪的Sagnac环内增加一段保偏光纤,控制两段保偏光纤快轴熔接角度接近45°,设计并制造了保偏光纤转轴熔接Sagnac干涉环结构。在理论上通过Jones矩阵推导了保偏光纤转轴熔接Sagnac干涉环的干涉谱公式,基于仿真分析研究了主要参数对保偏光纤转轴熔接Sagnac干涉环输出特性的影响。仿真结果表明,保偏光纤转轴熔接Sagnac干涉环实现了光学游标效应,两段保偏光纤的平均长度、两段保偏光纤的长度差分别影响保偏光纤转轴熔接Sagnac干涉环输出干涉谱的波长间隔和包络周期;在实验中,将保偏光纤转轴熔接Sagnac干涉环应用在光纤温度传感器中。实验结果表明,在2cm的感温区域,保偏光纤转轴熔接Sagnac干涉环温度传感器的灵敏度就达到了-2.44nm/℃,是普通Sagnac干涉环温度传感器(-0.163nm/℃)的14.97倍。

An optical fiber Sagnac interference loop with two angle shift spliced polarization maintaining fibers was designed and fabricated to realize high-sensitivity temperature sensing.In the optical fiber Sagnac loop,two sections of polarization maintaining fibers were spliced with an intersection angle of 45° between their fast axes.The interference spectrum formula of the Sagnac interference loop by the Jones matrix was deduced theoretically.The influence of main parameters of the formula on the output characteristics of the Sagnac interference loop was studied in simulation.The simulation results show that vernier effect can be achieved in the optical fiber Sagnac interference loop with two angle shift spliced polarization maintaining fibers,of which the average length and the length difference affect wavelength intervals and envelope periods of output interference spectra of the Sagnac interference loop,respectively.In addition,the optical fiber Sagnac interference loop with twoangle shift spliced polarization maintaining fibers was applied as a fiber temperature sensor experimentally.The results show that the sensitivity of the proposed temperature sensor based on Sagnac interference loop is -2.44nm/℃ within 2cm temperature zone,which is 14.97 times as compared with that（-0.163nm/℃）of ordinary Sagnac loop sensors without vernier effect.