基于正方形格子的空芯光子带隙光纤的模式特性和泄漏损耗

Modal characteristics and leakage loss of hollow-core photonic bandgap fibers based on a square lattice

利用全矢量有限元法计算和分析了基于正方形格子的空芯光子带隙光纤的模式特性和泄漏损耗.通过分析发现,圆正方形空气孔按正方形格子排列的空芯光子带隙光纤可以实现宽带和有效的单模运转.随后对正方形格子空芯光子带隙光纤的泄漏损耗进行了全面分析,通过分析发现纤芯直径和包层空气孔间距的变化对泄漏损耗的影响较小,但可以通过调节包层空气孔间距来实现给定的波长具有最小的泄露损耗;圆化直径对泄漏损耗的影响较前两个因素要大,且存在一个最佳的圆化直径即dc/d=0.4;包层空气孔的层数是影响泄漏损耗的主要因素,每增加两层空气孔泄漏损耗大约会降低两个数量级.

In this paper the modal characteristics and leakage loss of hollow-core photonic bandgap fibers based on a square lattice with rounded square air holes was investigated by using a full-vector finite element method. It was found that hollow-core photonic bandgap fibers with air core arranged in square lattice can operate in the broad bandgap single mode. The leakage loss was analyzed comprehensively. Simulations show that the core diameter and the hole-to-hole spacing have a small influence on leakage loss, but for a given wavelength the desired lowest leakage loss could be obtained by tuning the value of hole-to-hole spacing, while the rounded diameter has a larger influence on leakage loss than the former factors and it has an optimal value dc/ d = 0.4. The number of cladding rings plays a key role in the leakage loss and the leakage loss is reduced by nearly 2 orders of magnitude per 2 additional cladding rings.