双S型光纤结构的传感特性

Sensing Characteristics of Daul S-shape Optical Fiber Structure

在剥除涂覆层的单模光纤上熔成两个间距为25mm的S型结构,构成双S型全光纤马赫-曾德干涉仪.入射光经过第一个S型结构时部分光被激发到包层,经过第二个S型结构时重新进入纤芯传播,S型结构中光纤的纤芯模和包层模耦合产生干涉.利用干涉光谱测量外界因素的响应并用于温度、折射率和微位移的测量.实验结果表明,温度、折射率和微位移的灵敏度分别为69pm/℃,132.64nm/RIU,-178pm/μm,且具有很好的线性度.该传感结构为全光纤结构,制作简单,易于实现且成本低.

A section of the single mode optical fiber stripping coated layer was discharged into two S-shape in a splicer at a distance of 25 mm and a Mach-Zehnder interferometer based on daul S-shape structure was formed.Part of the light can be excited into the cladding mode at the first S structure and return to the core mode at the second one.The S structure leads to the coupling between the core mode and the cladding mode and generates interference.Using the interference spectra to measure the response to external factors like temperature,refractive index,and micro displacement.Experimental results show that the sensitivities of temperature,refractive index and micro displacement are 69pm/℃,132.64nm/RIU,-178pm/μm,respectively,and the measurement has a good linearity.The sensor has the merits of all-fiber structure,easy-fabricated and low-cost.