用于光纤振动传感的盘片式振动增敏研究

Study on disk vibration sensitization for optical fiber vibration sensing

目前光纤传感器增敏的研究方向主要从改变光纤自身结构和成分的角度出发或者借助外部封装工艺来实现增敏效果,导致传感器研发制作的成本和时间都会大幅提升。为满足地震勘探和结构安全监测中分布式光纤传感系统对振动测量的实际需要,设计了一种基于马赫—曾德尔干涉仪(MZI)光纤干涉的盘片式振动增敏结构,结合弹性力学与光纤弹光效应对其灵敏度进行了推导;使用有限元方法分析了盘片参数对灵敏度的影响,通过对增敏结构的合理设计及优化确定了盘片的尺寸。基于此结构设计的振动传感器有效工作频率范围为0.1~2.5kHz,灵敏度可达6988.2 rad/gn,对于60 m外的震源可以采集到有效振动信号,能够满足振动监测领域的实际需要以及系统运行的经济性。

At present,research direction of optical fiber sensor sensitization is mainly from the angle of changing the structure and composition of the optical fiber itself or through the external packaging process to achieve sensitization effect,which result in a significant increase in the cost and time of sensor research and development.To meet the practical needs of distributed optical fiber sensor system for vibration measurement in seismic prospecting and structural safety monitoring,a disc-type vibration-sensitizing structure based on Mach-Zehnder optical fiber interference is designed,and its sensitivity is deduced by combining elastic mechanics and optical-elastic effect.The influence of disk parameters on sensitivity is analyzed by finite element method,and the size of disk is determined by rational design and optimization of sensitizing structure.The effective working frequency range of the vibration sensor designed based on this structure is 0.1~2.5 kHz,and the sensitivity can reach 6988.2 rad/gn.For a source beyond 60 m,the effective vibration signal can be collected,which can meet the actual needs in the field of vibration monitoring and the economy of the system operation.