We propose and experimentally demonstrate a highly sensitive temperature sensor based on cascaded high birefringence fiber loop mirrors (HiBi-FLMs) with the Vernier effect. The two HiBi-FLMs have almost the same free spectrum range (FSR), which can be regarded as two scales of different periods of an optical Vernier-scale, and act as the fixed part and the sliding part, respectively. A Gauss fitting algorithm is introduced to fit the Vernier spectrum envelope to accurately trace the spectral shift of the envelope. The temperature sensitivity and temperature resolution of the cascaded configuration are much larger than those of the individual HiBi-FLMs due to the Vernier effect. The experimental result shows that the temperature sensitivity of the proposed sensor can be improved from ${-}{1.723}\;{\rm nm}/^\circ {\rm C}$ (single HiBi-FLM) to ${-}{43}\;{\rm nm}/^\circ {\rm C}$ (cascaded configuration) by employing the Vernier effect, and the temperature resolution is enhanced from ${\pm} {0.029}^\circ {\rm C}$ to ${\pm} {0.001162}^\circ {\rm C}$. The amplification factors for temperature sensitivity and temperature resolution are both 24.96, which shows good agreement with the theoretical predictions. The proposed sensor with huge temperature sensitivity, high resolution, and simple configuration may be a promising candidate for some applications that need precise temperature control.

中文翻译：

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基于带游标效应的级联HiBi-FLM的高灵敏度温度传感器

我们提出并实验证明了一种具有级联高双折射光纤环形镜（HiBi-FLM）并具有游标效应的高灵敏度温度传感器。这两个HiBi-FLM具有几乎相同的自由光谱范围（FSR），可以将其视为光学游标刻度尺不同周期的两个刻度尺，分别用作固定部分和滑动部分。引入了高斯拟合算法来拟合游标频谱包络，以准确跟踪包络的频谱偏移。由于游标效应，级联配置的温度灵敏度和温度分辨率比单个HiBi-FLM的温度灵敏度和温度分辨率大得多。实验结果表明，所提出的传感器的温度灵敏度可以从$ {-} {1.723} \; {{rm nm} / ^ \ circ {\ rm C} $（单HiBi-FLM）通过Vernier效应到$ {-} {43} \; {\ rm nm} / ^ \ circ {\ rm C} $（级联配置），温度分辨率从$ { \ pm} {0.029} ^ \ circ {\ rm C} $到$ {\ pm} {0.001162} ^ \ circ {\ rm C} $。温度敏感性和温度分辨率的放大因子均为24.96，与理论预测值吻合良好。所提出的传感器具有巨大的温度敏感性，高分辨率和简单的配置，对于某些需要精确温度控制的应用而言，可能是一个有前途的候选对象。