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掺铒孔辅助导光光纤是由掺铒的高折射率纤芯、低折射率包层和少量的空气孔组成.采用有限元法分析了掺铒孔辅助导光光纤的模式特性;给出了数值计算截止波长和模场直径的方法;提出了改进的平均粒子数反转度迭代算法来数值计算掺铒光纤放大器的增益和噪声系数.研究空气孔对掺铒孔辅助导光光纤的截止波长、模场直径和放大器的增益系数的影响.发现:减小相对孔芯距的值,可使截止波长向短波长移动,减小模场直径的值;当孔的相对大小较大时,截止波长、模场直径和增益的最大值基本上不随孔的相对大小的增大而改变.最后,综合考虑掺铒光纤基模和二阶模的截止波长、与普通单模光纤的熔接损耗、放大器的增益和噪声系数等因素,优化设计了掺铒孔辅助导光光纤的四个结构参量——纤芯半径、纤芯与包层的折射率差、相对孔芯距和孔的相对大小.
The erbium-doped aperture-assisted light guide fiber is composed of erbium-doped high refractive index core, low refractive index cladding and a small amount of air holes. The mode characteristics of erbium-doped aperture-assisted light guiding fiber are analyzed by finite element method Numerical method to calculate cutoff wavelength and mode field diameter, and an improved iterative algorithm of average particle number inversion is proposed to numerically calculate the gain and noise figure of erbium-doped fiber amplifier.The effect of air hole on the cutoff wavelength , The mode field diameter and the gain factor of the amplifier. It is found that decreasing the value of the relative hole-core distance can make the cutoff wavelength shift to the short wavelength and reduce the value of the mode field diameter. When the relative size of the hole is larger, The maximum wavelength, mode field diameter and gain basically do not change with the relative size of the hole.Finally, considering the cut-off wavelength of the fundamental mode and the second-order mode of erbium-doped fiber, Gain and noise figure, the four structural parameters of the erbium-doped fiber assistant-guided fiber - the core radius, the refractive index difference between the core and cladding, the relative core spacing and the relative size of the holes, are optimized.