摘要
依据光纤波导中的电磁场传输基本理论，计算了光纤波导中的电磁场分布、约束系数及色散系数随折射率的变化关系，开展了γ射线对融石英材料及色散位移光纤的辐射实验。实验验证了理论计算结果，得到了折射率及色散系数随吸收剂量的变化关系。计算及实验结果均表明：1）光纤的折射率随吸收剂量的增加而增大，辐射效应使电子密度增大是折射率改变的主要因素。2）折射率的变化会引起传输模式的场强分布变化，从而导致光纤的辐射感生波导损耗；在吸收剂量0～2000Gy内，光纤仍满足弱导边界条件，能够维持对传输模式的约束。3）光纤的色散系数随吸收剂量的增加而增大，在吸收剂量0～500Gy内，光纤色散增加量呈逐渐饱和趋势；暴露在核辐射环境中的长距离光纤，其快脉冲光波信号将产生展宽畸变。
Based on the basic theory describing the electromagnetic wave transmission in optical fiber waveguides, the electromagnetic field distribution, confinement factor, and dispersion coefficient, which change with the refractive index of the optical fiber, were calculated. The y-ray radiation experiments on fused silica and dispersion-shifted fiber were carried out, demonstrating the calculation results. The refractive index and dispersion coeffi- cient varying with the absorbed dose of the fiber irradiated by the y-rays were obtained. The experimental and theoretical results show that： 1） the refractive index of the optical fiber increase with the absorbed doses, and the main causes for its increase is the increase of the electron density induced by y-ray radiation; 2） the changes in the refractive index would cause the variations in the field distribution of the transmission mode, resulting in radiation- induced waveguide losses; and within the dose range of 0-2 000 Gy, the optical fiber would still meet the weakly guiding boundary conditions and maintain the confining ability on the transmission mode; 3） fiber dispersion coefficient increases with the absorbed dose, and within the dose range of 0 - 500 Gy, the fiber dispersion coefficient exhibits a gradual increase in the amount of saturated trends, and therefore leading to distortion of the fast pulsed signals resulted from pulse period spreading.
出处
《现代应用物理》
2015年第3期202-208,共7页
Modern Applied Physics
基金
国家自然科学基金资助项目(11275148)
关键词
Γ辐射
光纤波导
折射率
电磁场分布
约束系数
色散系数
gamma-ray radiation
optical fiber waveguide
refractive index
distribution of electromagnetic field
confinement factor
dispersion coefficient
