基于石墨烯和模间干涉的光纤气体传感器

为了实现对空气中有毒、有害气体进行精确监测预报，提出了一种石墨烯包裹的拉锥与错位级联型光纤气体传感器.包裹在光纤锥形传感区域的单层石墨烯和错位熔接的光纤导致的模间干涉，会使沿光纤表面传输的倏逝场得到大幅增强，提高了对折射率的灵敏度，其灵敏度可以达到1.2×10⁴nm.随着石墨烯表面吸附的气体分子量的增加，复合波导的有效折射率会发生规律性的变化，从而引起干涉波长的衰减和移动，进而通过检测输出光信号的变化而实现气体分子浓度的检测.研究表明，该传感结构具有体积小、机械强度好、光谱品质好、灵敏度高等优点.

Optical Fiber Gas Sensor Based on Graphene and Intermodal Interference

In order to precisely monitor and forecast noxious and harmful gases in the air， an optical fiber gas sensor was proposed including a section of tapered and dislocated optical fiber， and the tapered region was coated with graphene. The tapered fiber sensing area which was wrapped with graphene and intermodal interference caused by the dislocation of fiber would substantially increase evanescent field， which transmitted along the surface of fiber， and would have a significant sensitizing effect on the gas sensing of the optical waveguide. At the same time， the gas molecules adsorbed on the surface of graphene would lead to change of the effective refractive index of the composite waveguide， resulting in the corresponding wavelength drift and attenuation. By detecting the change of the output optical signal， the concentration of gas molecules could be detected. Based on this principle， the sensor realized a gas sensitivity of 1.2×10⁴nm. The research shows that the sensing structure has the advantages of small volume， good mechanical strength， good spectral quality and high sensitivity etc.