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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80 nm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1.14 nm,其敏感度达到折射率变化~5×10-4谐振波长改变20 pm。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 new type of long-period fiber grating sensor coated with metal film is proposed. The sensor based on surface plasmon resonance with three-layer structure is divided into two parts. The grating part is made by continuous CO2 laser pulse, and the metal film is made by vacuum coating. The grating is coated with thin metal films of various thicknesses to excite the surface plasmon wave. The fiber grating sensor is used to measure the refractive index of the liquid and to study the characteristics of its reflection resonance spectrum. At standard pressure, the gratings coated with a silver film of 80 nm change the grating resonant wavelength by 1.14 nm from water (ns = 1.33) to alcohol (ns = 1.36) with a sensitivity of ~ 5 × 10 -4 resonance Wavelength changes 20 pm. The study found that different thicknesses of different metal films show different sensitivities. The sensitivity of this reflective long-period fiber grating sensor is obtained by comparing the grating’s resonant wavelength in air, water, alcohol, glycerol, and in their mixture solution. It provides a useful reference for fabricating a high-performance FBG sensor for measuring the refractive index.