基于交替光栅和石墨烯复合结构的折射率传感器

Refractive Index Sensor Based on Alternating Grating and Graphene Composite Structure

为了消除折射率动态检测中环境温度漂移的干扰,提出了一种基于交替光栅和石墨烯复合结构的超材料传感器。利用时域有限差分法数值模拟了传感器结构设计参数对共振光谱的影响规律并研究了耦合机理,同时优化了设计结构。研究结果证明,复合结构传感器具有多通道和超窄线宽双重光谱特性,且近红外频段高吸收光谱是由F-P腔共振效应、磁激元共振效应和相消干涉耦合激发产生的。基于不同共振模式下折射率和温度敏感度的差异性,选择两个共振峰峰位波长作为信息载体,借助矩阵方程获得的温度补偿后的折射率传感灵敏度可达358.6 nm/RIU。结果表明,所提传感器可对1~1.6 RIU超大折射率范围的样品进行实时动态监测,同时能消除温度漂移的影响,更具实用性。

To eliminate the interference of ambient temperature drift in the dynamic refractive index measurement,we propose a refractive index sensor based on a metamaterial structure with alternating grating and graphene.The effect of structure parameters on the response spectra is numerically simulated by the finite-difference time-domain method,the coupling mechanism is analyzed,and the designed structure is optimized.The research results indicate that this sensor with a composite structure possesses the dual spectral characteristics of multi-channel and ultra-narrow linewidth.In addition,the high absorption spectrum at near-infrared region is attributed to the coupling and excitation by F-P cavity resonance effect,magnetic polariton resonance effect,and destructive interference.Based on the differences in refractive index and temperature sensitivity under different resonance modes,with two resonant peak position wavelengths as information carrier and under the help of a matrix equation,the refractive index sensitivity reaches 358.6 nm/RIU after temperature compensation.The results show that the proposed sensor is effective in the real-time dynamic monitoring of samples in the wide refractive index range(1--1.6 RIU),and can avoid the influence of temperature drift,and thus it has more practicability.