基于损失模式共振的光纤湿度传感特性研究

Research on the sensing properties of lossy mode resonance-based fiber optic humidity sensor

摘要:

提出一种基于高分子湿敏材料涂覆的光纤损失模式共振(lossy mode resonance,LMR)湿度传感器,以多模光纤为基底,使用层层自组装(layer-by-layer assembled,LBL)方法在纤芯表面沉积二氧化钛(titanium dioxide,TiO₂)以激发LMR效应,并通过理论和实验验证了其对于折射率变化的敏感性。以聚乙烯醇(polyvinyl alcohol,PVA)和聚酰亚胺(polyimide,PI)分别作为湿敏材料制作LMR湿度传感器,通过观察吸收光谱中共振峰的偏移来实现对周围环境湿度变化的监测。实验结果表明,两种传感器都能实现湿度的传感,且表现出相近的传感特性,其中PVA传感器在60%RH—90%RH湿度区间,灵敏度最高可达到2.94 nm/%RH,两种传感器湿度灵敏度高、可逆性、重复性好,在湿度检测领域有广泛的研究和应用前景。

Abstract:

A lossy mode resonance (LMR)-based fiber optic humidity sensor coated with polymeric humidity-sensitive materials is proposed.Titanium dioxide (TiO₂) is deposited on the multimode fiber core using the layer-by-layer assembled (LBL) technique to excite LMR effects.The refractive index sensitivity of the LMR sensor is systematically investigated through both theoretical analysis and experimental validation.Two distinct humidity sensors are fabricated by employing polyvinyl alcohol (PVA) and polyimide (PI) as the functional sensing layers, respectively,where humidity detection is achieved by monitoring the resonance wavelength shift in the absorption spectrum. Experimental results demonstrate that both sensors exhibit effective humidity-sensing capabilities with comparable performance characteristics. Notably,the PVA-based sensor achieves a maximum sensitivity of 2.94 nm/%RH (relative humidity) within the 60%RH—90%RH range. Owing to their high sensitivity,excellent reversibility,and outstanding repeatability,the proposed sensors exhibit significant potential for practical applications in humidity monitoring.