采用有限元方法和耦合模理论,分析了圆型大空气孔微结构光纤Bragg光栅的光谱特性,并进行了数值计算。结果表明,随纤芯半径的增大,此类光纤光栅纤芯模式和包层模式的谐振峰向长波长方向漂移。随包层空气孔半径的增大,包层谐振峰向长波方向漂移,并逐渐趋于稳定值。随包层空气孔中填充材料折射率的增大,纤芯模式谐振峰中心波长不变,而第一二三阶包层谐振峰向长波长方向具有明显漂移。

Based on the finite element method and coupled mode theory, the characteristics of the reflection spectrum of the large-air-hole micro-structured optical fibers Bragg grating was analyzed and numerically calculated. The results show that the resonance wavelength of the core mode and the cladding mode of the grating would shift to the longer wavelength as the increase of the radius of the core, the resonance wavelength of the cladding mode tend to be a fixed value as the increase of the radius of the air holes in the cladding. However, the resonant wavelength of the core mode wouldnt change as the refractive index of the filled in the air holes increased while the resonant wavelength of first, second and the third modes have a great shift.