提出了以聚酰亚胺(PI)为感湿材料的三耦合点单微环新型湿度传感器。外界湿度变化使得聚酰亚胺SOI微环谐振特性发生变化, 最终通过谐振波长的漂移量确定湿度值。讨论了不同部位感湿时系统的传感特性, 并且选择了最佳湿敏元件。数值模拟结果表明: 与传统的单微环传感器相比, 新型传感器具有较高灵敏度和测量范围, Through端口的自由频谱范围可提高3倍。三耦合点单微环谐振器整体结构可作为最佳湿敏元件, 该传感器在10%RH~80%RH相对湿度范围内, 灵敏度可达到0.98 nm/%RH, 该结构为制备高灵敏度可集成微型湿度传感器件提供了一定的理论依据。

A novel optical humidity sensor based on single microring with three couple points was proposed, and polyimide (PI) was used as the moisture material. The transmission characteristics of the PI microring vary with the environmental humidity, which leads to the shift of the output optical spectrum. Humidity was measured by detecting the drift of the output spectrum, meanwhile, the optimal humidity sensing part was selected and the sensing properties of different sensing-parts were discussed. The numerical results show that the sensitivity and the sensing-range are improved obviously and the free spectral range (FSR) of the structure is tripled compared to the conventional single microring sensor. Moreover, the whole structure of single micro-ring with three couple points could be served as the optimum sensing part. The sensitivity of the humidity sensor is up to 0.98 nm/%RH and the sensing relative humidity range is from 10%RH to 80%RH. The structure in this paper is of great importance to low-cost and high sensitivity humidity sensor.