光子晶体光纤耦合损耗的数值研究

光子晶体光纤(PCF)与普通单模光纤(SMF)以及不同结构光子晶体光纤之间的耦合损耗是急待解决的问题,采用光子晶体光纤的本地正交函数模型,对光子晶体光纤与普通单模光纤以及不同结构光子晶体光纤之间的耦合损耗进行了分析计算,得到了耦合损耗随光子晶体光纤结构参量以及波长的变化关系,给出了最优耦合的光子晶体光纤的结构参量。结果表明,PCF的孔距Λ是影响PCF与SMF耦合损耗的最主要因素,当Λ为某个特定值时,PCF与SMF的模场半径相等,耦合损耗最小,偏离这个特定值时的耦合损耗都会增大;PCF之间的耦合损耗取决于它们孔距的差异;此外由于模场半径与波长有关,当波长为某个特定值时,PCF与SMF模场半径相等,此时耦合损耗也最小。因此,在PCF设计过程中应综合考虑这些相关因素。

Number study on the coupling loss of the photonic crystal fiber

The coupling loss between photonic crystal fiber(PCF),single mode fiber(SMF),and other PCF with different structure is an urgent problem to be solved today. The local orthogonal functions model of PCF was applied to theoretical analysis of the coupling loss between PCF,SMF and PCF with different structures. The relation between coupling loss and the structural parameter of PCF and mode wavelength was obtained,and the optimal structural parameter was given. The result shows that(1)the main factor that affects the coupling loss between PCF and SMF is the hole space A of PCF. When the hole space is fixed to a certain value and the mode radii of PCF and SMF are the same,the coupling loss reaches its minimum value,i. e.,any deviation from this value will increase the coupling loss;(2)The coupling loss between PCFs is determined by the difference of their hole spaces. As the mode radius depends on mode wavelength,the coupling loss will also be in its minimum value when wavelength keeps constant and the mode radii of PCF and SMF are the same. Therefore,the factors should be comprehensively considered in the design process of PCF.