【摘要】 提出了一种双包层单模光纤传感器结构,根据波导理论推导出了光纤中导模变为泄漏模时,外包层折射率与双包层结构参量之间的关系,获得了这种光强调制型传感器可测量的折射率变化范围。利用已知热光系数的材料制作的温度传感器,从实验上证实了理论分析结果,并由理论与实验结果的分析得到了传感器的工作原理是:导模变为泄漏模后,输出光强与外包层一定范围的折射率变化有准线性关系。获得了在55~105℃的温度范围内的具有准线性响应的温度传感器,光强变化范围达到了39 dB;提出了利用一种围栏结构在光纤上涂覆敏感材料的简便方法,用琼脂糖制作出了插入损耗仅0.5 dB、相对湿度(RH)在30%~100%范围具有准线性响应、光强变化范围接近9 dB的光纤湿度传感器。更多还原

【Abstract】 A new type of sensor based on a doubly cladding single-mode optical fiber is proposed.The measurable range of the refractive index changes for the sensors is analyzed theoretically and demonstrated experimentally,which corresponds to the case that the fundamental mode in the fiber becomes leaky.Based on the analysis for the theoretical and the experimental results,the principle of the sensor is got.The output of the optical power of the sensor is almost inversely proportional to the refractive index of the outer cladding in some range of variation after the base mode in the fiber becoming leaky.A sensor with a linear response in the temperature range of 55~105 ℃ and an optical power variation of 39 dB is obtained.A new method of recoating hydrogels on optical fibers is verified.A humidity sensor fabricated by agarose shows a power variation of 9 dB in the moisture range of 30%~100%RH and insertion loss of 0.5 dB.更多还原