菱形晶格多孔光纤偏振拍长的波长敏感性优化

Optimized Design for Beat-Length Stability of the Holey Birefringence Fiber with Diamond Lattice

针对菱形晶格多孔光纤，应用全矢量有限差分光束传播法分析了纤芯附近一对特殊气孔、本底气孔以及对角线上的气孔间距对偏振拍长波长敏感性的影响，初步得出包层结构的优化参数，再通过横向伸缩形变引入两种新的非对称结构，进一步抑制多孔光纤原有双折射随波长的非线性变化，在降低偏振拍长波长敏感性的同时包层结构的几何参数也获得了较大的误差容限，结果表明，偏振拍长的中值为132．5mm，在波长1．2～1．7μm范围内，相对变化率小于土4％，同时优化后包层结构的几何参数误差容限大于0．1μm，为制作多孔光纤宽带消色差波片提供了较为可行的工艺参数。

For the holey fiber with diamond lattice, the influence of the special holes near the core, the bottom holes and the pitch of diagonal holes on the wavelength sensitivity of polarization beat length is analyzed. The preliminary optimal cladding structure parameters are obtained. Then two new asymmetric structures are introduced through the lateral deformation. The holey fiber original non-linear variation of birefringence with wavelength is further suppressed. The wavelength sensitivity of the polarization beat length is reduced while a larger error tolerance of the cladding structure geometrical parameters is obtained. The results show that the median value of polarization beat length is about 132.5 mm and the relative variation of polarization beat length is less than ~ 4 % in wavelength range of 1.2~ 1.7 μm while the error tolerance of optimized geometric parameters is greater than 0.1 μm. The more feasible process structure parameters are provided for drawing the achromatic holey fiber wave plates with broadband.