完整抛磨光纤光栅3层介质波导模型数值模拟

Numerical Simulation ofThree-layer Dielectric Waveguide Model of Integrity Polished Fiber Bragg Grating

应用3层结构光纤波导模型,借助计算软件改变外界折射率、剩余包层厚度等参数,对完整抛磨光纤光栅在外界环境影响下的Bragg波长变化进行数值模拟。数值模拟的结果表明,随着外部环境折射率的提高,有效折射率从初值渐骤升至最大值,后略有下降,Bragg波长表现为外界折射率接近纤芯折射率时,红移而又略回蓝移。在设定不同的外界折射率情况下,光纤光栅的有效折射率都呈现出当包层半径较大时保持不变,包层半径减小到某值后光纤光栅的有效折射率突然增加,达到顶峰的有效折射率仍小于各自的外界折射率。所得结果对于侧边抛磨光纤光栅的设计、液位测量和折射率传感技术具有重要的指导意义。

With the help of computing software,the Bragg wavelength change is simulated under the influence of the external environment using the three-layer fiber waveguide model.The result shows that if surrounding refractive index increases,effective index gradually swells to maximum level from the initial value with a slight decline.The Bragg wavelength red shifts and slightly blue are shifted back when external refractive index is close to the core refractive index. The effective refractive index of the fiber grating remains the same if the cladding radius is larger.But it could suddenly increase when the cladding radius reduces to a value.The effective refractive index of the peak is still smaller than the respective refractive index of the outside world.The results have important guiding significance for the side polished fiber Bragg grating design,level measurement and refractive index sensing technology.