双芯光子晶体光纤中的模式干涉

应用全矢量超格子叠加模型分析了双芯光子晶体光纤(PCF)的模式特征.双芯PCF的基模和二次模分别由偏振方向不同的两个偶模和两个奇模组成，讨论了这四个模式的模式电场奇偶性.基于对双芯PCF模式电场奇偶性的认识，讨论了光纤中的矢量模式干涉问题.分析表明，不同偏振态模式的干涉不会引起芯间的功率转移，双芯PCF的芯间功率耦合是由相同偏振模式的干涉引起的.在相同偏振模式干涉过程中，光功率在两个芯子中呈余弦振荡，光纤的两个芯子一般存在约π／2的相位差.还讨论了两个不同偏振方向的耦合系数与波长的关系. 关键词： 光子晶体光纤 双芯光纤 模式 干涉 耦合

Modal interference in dual-core photonic crystal fibers

The modal characteristics of dual-core photonic crystal fibers(PCFs) are analyzed by a full vector supercell lattice overlapping model. The fundamental and second-order modes of dual-core PCFs consist of a pair of even and odd modes with different polarization. The parity properties of the modal electric field for the fundamental and second-order modes are discussed. Based on the analysis of parity of the modal electric fields, we investigated the vector modal interference in dual-core PCFs.It is the interference between two same polarized modes that conributes to the inter-core coupling of power. It is shown that the optical power will oscillate from one core to the other and the phase difference between both cores is about π/2. The dependence of coupling coefficients for different polarization on wavelength is discussed.