为提高系统的测量范围、灵敏度与线性度, 利用拉锥光纤替代均匀光纤, 进行表面等离子共振光纤传感器性能优化研究.通过大功率激光熔融拉锥工艺, 结合圆环靶磁控溅射制备了锥形光纤等离子共振探头;利用光纤光谱仪, 在1.33-1.43RIU折射率变化范围内, 以探头的表面等离子共振吸收谱对称性、吸收谱半高全宽的稳定性, 以及探头共振吸收波长分辨率为指标, 进行探头性能测试与筛选;利用筛选出的探头, 基于调频光谱原理构建闭环检测系统;在相同检测对象与检测环境条件下, 以阿贝折射率仪测量结果为参照, 对均匀探头与锥形探头的检测结果进行比较.结果表明, 在1.33-1.43 RIU范围内, 相对于均匀光纤探头0.00032 RIU的测量准确度、2 600 nm/RIU的波长分辨率, 锥形探头可在较大折射率变化范围内, 以较好的线性度, 实现0.00003 RIU测量灵敏度和约4 500 nm/RIU的波长分辨率.

For the sake of optimizing its measure range,sensetivity and linearity, a tapered Surface Plasmon Resonance (SPR) fiber probe was applied as the substitution of the uniform fiber probe because of its abundant lossy modes.Simulation results and experimental data shew that this tapered probe had a SPR asorption spectrum with better symmetry and its resonance wavelength could change responsing to a bigger range of measured refractive index with a stable wavelength resolution. After constructing a closed-loop SPR fiber sensors based on the tapered probe according to frequency modulation principle, the deionized water sucrose and ethanol solution, whose refractive index value ranged from 1.33 RI unit (RIU)to 1.43 RIU with different concentration, were elected as measurand.The measured results were analyzed and verfied using an Abel refractive index meter.The experimental results demonstrated that the closed-loop SPR fiber-optic sensors with a tapered SPR probe had the sensitivity of 0.00003 RIU, wavelength resolution of 4500 nm/RIU and with better performance in terms of dynamic range, sensetivity and linearity, than that with a uniform SPR probes.