倾角对闪耀光纤光栅辐射模耦合波长的影响

Effect of tilted angle on radiation coupling wavelength in tilted fiber Bragg gratings

不同角度下,闪耀光栅发生辐射模耦合的波长有所不同。文章利用相位匹配条件定性分析了辐射模耦合波长随倾斜角度的变化;使用耦合模方程对闪耀光栅的透射谱特性进行数值仿真,仿真结果与相位匹配条件分析得到的结果一致:若设计Bragg波长保持不变,当光栅倾角变大时,发生辐射模耦合的波长变短。通过比较0～45°范围内s和p偏振情况下耦合波长的差异,得出辐射模耦合的偏振依赖特性,此特性可用于传感检测。

The wavelength at which the strongest radiation-mode coupling occurs is related with the tilted angle of the tilted fiber Bragg grating. The relationship is qualitatively analyzed by phase matching conditions and numerically analyzed utilizingcouple mode equations. The conclusion from both methods agrees well： when the tilted angle increases, the coupling wavelength becomes shorter. The difference between s-polarized and p-polarized radiation-mode coupling of the dependence on grating tilted angle are compared, and the results show that the coupling strength greatly depends on the polarization state of the core mode which can be taken good advantage in sensor fields.