设计了基于断环结构的全固光子带隙光纤,其背景材料为熔石英而断环结构由若干掺杂的高折射率介质柱构成.基于平面波展开法计算得到的态密度图和Bloch模场分布表明,该种光纤中的一个高阶带隙可以得到调节并被极大展宽,带隙调节的基本原理是断环可以同时控制包层介质柱的线偏振模式的角向和径向模式阶数.研究表明,断环中的介质柱数目决定了受影响最小的一组线偏振模式的最高角向阶数,而带隙宽度受介质柱尺寸影响很大.这一宽的高阶带隙可以用来设计带隙中心分别在800和1550nm、带宽分别为488和944nm的全固光子带隙光纤,且带隙内的缺陷模式具有典型的正常-零-反常色散特性.
The design of all-solid photonic bandgap fibers based on a high-index broken ring is investigated,where the background material is silica and the broken ring consists of several individual high-index rods.Density of states maps and Bloch mode field distributions obtained by plane wave expansion method show that a high-order bandgap in such fibers can be engineered and broadened.The principle is that both the azimuthal and the radial orders of the LP modes of the high-index rods in the cladding can be controlled by the broken ring.It is demonstrated that the highest azimuthal order of the group of less affected LP modes is determined by the rod number and the bandgap width is largely affected by the rod size.The high-order bandgap can be used to design all-solid photonic bandgap fiber with broad transmission ranges of 488 nm and 944 nm for a center wavelength of 800 nm and 1550 nm,respectively,and the transmission window features the typical normal-zero-anomalous dispersion profile.