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长周期光纤光栅是一种性能优良的光纤无源器件,在光纤传感方面用途广泛。利用高频CO2激光器在涂覆层没有剥除的光纤上刻写了长周期光纤光栅,进行了液体浓度传感特性实验研究。实验结果表明:带涂覆层的长周期光纤光栅的谐振波长与峰值损耗对液体浓度变化不敏感,涂覆层可以缓冲外界环境折射率变化对长周期光纤光栅特性的影响。若考虑传感应用中的机械强度要求,在相同条件下带涂覆层的长周期光纤光栅更适合作为对环境折射率不敏感的传感元件使用。
Long-period fiber gratings are excellent fiber-optic passive components and are used in a wide range of fiber sensing applications. Long-period fiber gratings were inscribed on high-frequency CO2 lasers without any stripping of the coating layer, and liquid concentration sensing characteristics were experimentally studied. The experimental results show that the resonance wavelength and peak loss of the long-period fiber grating with coating are insensitive to the change of liquid concentration. The coating can buffer the influence of the change of the refractive index of the external environment on the characteristics of the long period fiber grating. Considering the mechanical strength requirements in sensing applications, long-period fiber gratings with a coating under the same conditions are more suitable as sensing elements insensitive to the environmental refractive index.