矩形晶格微结构光纤偏振拍长稳定性的优化

Optimization of Polarization Beat Length Stability of Rectangular Lattice Microstructure Optical Fiber

针对纤芯两侧具有一对大圆孔的矩形晶格微结构光纤，分别在两个正交方向上进行压缩或伸展，利用多种非对称结构的双折射相互平衡与补偿，抑制双折射随波长的非线性变化。应用全矢量有限差分波束传播法数值模拟分析了横向伸缩形变对模式双折射和偏振拍长色散特性的影响。通过优化设计，找出了合适的伸缩因子，有效降低了偏振拍长的波长敏感性。在1．0～2．0μm波长范围内，偏振拍长值在90．7～95．3mm之间变化，相对变化率约为5％。这种矩形晶格微结构光纤适于制作宽带1／4波片。

A rectangular lattice micro-structure optical fiber with a pair of large circular holes near the core is squeezed or expanded in orthogonal directions. Nonlinear variation of birefringence with wavelength is suppressed by the compensation and equilibrium among the birefringence of multiple asymmetric structures. The influence of lateral deformation on modal birefringence and polarization beat length dispersion is analyzed by full-vector finite-difference beam propagation method. A suitable expansion factor is found by optimizing the design. The wavelength sensitivity of polarization beat length is effectively reduced. The polarization beat length changes in the range of 90. 7 95.3 mm and the relative variation is about 5 % in the wavelength range of 1.0-2.0μm. This fiber is very suitable for making wideband fiber-optic quarter wave plate