摘要
提出了一种新型的单端面反射的镀有金属膜的长周期光纤光栅传感器。这种基于表面等离子体谐振的具有三层结构的传感器分为两个部分，光栅部分用连续CO2激光脉冲制作，金属膜是由真空镀膜制成。在光栅上镀上各种不同厚度的薄金属膜来激发表面等离子体波，用这种光纤光栅传感器来测量液体的折射率，并研究它的反射谐振谱的特性。在标准气压下，镀有80nm银膜的光栅从水（ns=1.33）到酒精（ns=1．36）中光栅谐振波长改变了1．14nm，其敏感度达到折射率变化～5×10^-4谐振波长改变20pm。研究发现不同厚度的不同金属膜显示了不同的敏感度。通过比较光栅在空气，水，酒精，甘油，以及在它们的混合物溶液中的谐振波长，得到这种反射式的长周期光纤光栅传感器的敏感特性。为制作一种高性能的用来测量折射率的光纤光栅传感器提供了一个有益的参考。
A novel single-ended reflecting Long Period Fiber Grating （LPFG） sensor with thin metal film overlay and the sensing system is described. An all-fiber reflection LPFG sensor with three-layer structure （core, cladding and metal） based on Surface Plasma Resonance （SPR） is established experimentally and fabricated with a pulsed CO2 laser writing system and vacuum evaporation coating system. Different nm-thick thin metal films are deposited on the reflected LPFG sensor for the excitation of Surface Plasma Waves （SPWs） and the characteristics of the reflection resonance spectra of the LPFG sensor for measuring refractive index of fluids are studied. In atmosphere condition, the peak wavelength shiiis about 1.14 nm as the sensor with only 80nm Ag film coated is put from water （ns=1.33） into alcohol （ns=1.36）.With the accuracy of wavelength measurement （20pm）, the SPR-LPFG sensors are expected to have a sensitivity to detect ns （surroundings refractive index） with a change of-5×10^-4. It is found that different thicknesses of different metal films show different measuring sensitivity. Through the comparison of the resonance wavelength obtained in air, water, alcohol, glycerin and their mixture solution, different sensitivities of the reflected SPR-LPFG sensors have been achieved. The proposed SPR-LPFG sensing scheme offers an efficient platform for achieving high performance fiber sensors for measuring ambient refractive index.
出处
《光电工程》
CAS
CSCD
北大核心
2009年第7期144-150,共7页
Opto-Electronic Engineering
基金
安徽省教育厅自然科学基金项目(KJ2008B26ZC)
