高阶模滤除法抑制蓝宝石光纤光栅反射谱带宽  

Reducing bandwidth of sapphire crystal fiber gratings based on rejecting higher order mode method

作　　者：王艳红[1] 王高[1] 郝晓剑[1] 

机构地区：[1]中北大学仪器科学与动态测试教育部重点实验室,山西太原030051

出　　处：《红外与激光工程》2012年第11期3075-3078,共4页Infrared and Laser Engineering

基　　金：山西省太原市科技局明星专项(120247-20);重点实验室青年基金项目

摘　　要：蓝宝石光纤布拉格光栅在超高温恶劣环境下参数测试领域具有广泛的应用前景。但由于蓝宝石光纤本身的特性,不能支持单模传播,其反射谱带宽较宽,对测量精度造成了影响。利用光纤弯曲滤除高阶模的方法,使蓝宝石光纤实现基模传输。针对目前商用的150μm芯径蓝宝石光纤,基于耦合模理论,通过一系列数值计算,得出了能够满足基模传输且不损耗基模能量的弯曲半径,并得出了弯曲半径与布拉格中心波长的漂移特性。通过数值计算和优化设计,在一定弯曲半径下,反射谱带宽可减小到3 nm。这一结果大大提高了蓝宝石光纤布拉格光栅传感器的测量灵敏度,为蓝宝石光纤光栅在高精度、超高温测试场合的使用提供了方法和理论依据。Sapphire fiber Bragg gratings （FBG） have broad application prospects in the parameters measurement in harsh environment with ultra-high-temperature. But sapphire FBG＇s reflection spectrum bandwidth is wider because sapphire fiber cannot support a single mode propagation, which has impact on measurement accuracy. In this paper, the fiber bending method for filtering out higher order mode was proposed, and the sapphire fiber fundamental mode transmission was achieved. Based on the coupled mode theory, a series of numerical calculations were completed for the current commercial 150 μm core diameter sapphire fiber. According to the calculation results, the bending radius of meeting the fundamental mode transmission was achieved without energy loss of the fundamental mode. Besides, drift characteristice of the bending radius and the Bragg wavelength were also gotten. By numerical calculation and design optimization, the reflection spectrum bandwidth could be reduced to 3 nm under a certain bending radius. This result greatly improves the measurement sensitivity of the sapphire fiber Bragg grating sensors, and provides methods and theoretical basis for sapphire fiber grating used in high- precision, ultra- high-temperature test occasions.

关 键 词：蓝宝石光纤布拉格光栅 耦合模理论 高阶模 反射谱 弯曲损耗 

分 类 号：TN25[电子电信—物理电子学]