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长周期光纤光栅的折射率敏感特性 总被引:1,自引:0,他引:1
利用光波导的耦合模理论分析了长周期光纤光栅(LPFG)的折射率传感特性,给出了LPFG 的谐振波长相对于环境折射率变化时的漂移量解析表达式.对 LPFG 的折射率传感特性进行了数值模拟.结果表明:在光栅周期不变的情况下,当包层折射率小于且接近外界环境折射率时,波长的漂移量增大,且对应的模次越高、包层半径越小、包层折射率越小,波长漂移量越大,即 LPFG 对应于外界折射率传感灵敏度得到显著提高;当外界环境折射率大于包层折射率时,光栅的谐振波长将近似不变. 相似文献
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为了提高长周期光纤光栅对环境介质折射率的传感灵敏度,提出一种长周期光纤光栅的周期和包层半径的结构优化.基于长周期光纤光栅的耦合模理论,分析了长周期光纤光栅的周期和包层半径的大小分别与环境介质折射率传感灵敏度的关系,讨论了长周期光纤光栅的周期和包层半径对折射率传感的影响以及控制光栅周期与包层半径对折射率传感的重要性.为使优化的长周期光纤光栅具有实用性,谐振波长设计在1.55 μm的常规波长范围,经过多次摸拟实验,提出最佳优化参量为:Λ=380 μm,rcl=17 μm,对环境介质折射率从1.26~1.38不同值的实验测试,折射率传感灵敏度达到0.000 12,长周期光纤光栅的结构优化获得理想的预期效果. 相似文献
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《Current Applied Physics》2020,20(10):1103-1109
We demonstrate a highly efficient, broadband fiber-optic intermodal converter. The technique relies on a long period grating mechanically induced in a two-mode fiber. A compact, portable apparatus was designed and fabricated, where period-variable metallic corrugation is implemented to form periodic micro-bends along the fiber. The coupling strength between the interacting fiber modes and the grating period can be tuned continuously and individually using two control knobs in the apparatus. Experimental results show that the complete coupling between the LP01 and LP11 modes is achieved, which is confirmed by an observed over-coupling while increasing the grating strength. For the short fiber length of <1.9 cm (33 grating periods), large band-rejection of −32.5 dB was obtained at resonance. The band rejection efficiency over 98.6% have been achieved in the entire communication C-band. As the grating strength increased, two over-couplings were observed at resonance, which indicates the high efficiency of the device. Experimental results are confirmed by our numerical simulations. 相似文献
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The performance of long period fiber grating (LPFG) sensors written in single cladding and double cladding fibers have been compared by using a fast responding interrogation system based on intensity modulation. Temperature and dynamic strain monitoring using this system have been demonstrated. This system is capable of resolving strain to 0.2 and 0.4 με at a loading frequency of 20 Hz, and temperature resolution to 0.02 and 0.19 °C by using LPFG in the single cladding (SC-LPFG) and double cladding (DC-LPFG), respectively. 相似文献