超低损耗孔助光纤弯曲性能优化设计

建立了弯曲光纤的二维轴对称有限元分析模型，对初始光纤弯曲性能进行了有限元分析，分别计算其弯曲损耗，有效模场面积和连接损耗；选取芯层到下陷层距离b，下陷层宽度c，下陷层深度t，空气孔孔径r为设计变量，以弯曲损耗和连接损耗最小为目标，利用正交试验和灰度关联分析相结合的方法对光纤弯曲性能进行了多因素多目标优化设计。研究结果表明:优化后光纤弯曲损耗从0.127 8 dB/m减小到1.749 810-4 dB/m；有效模场面积从94.741 m2减小到82.37 m2；连接损耗由0.174 3 dB减小到5.80510-4 dB。与标准单模光纤对比发现，新型光纤在弯曲半径为3 mm的情况下，有效模场面积从209.21 m2减小到82.3 m2，连接损耗从7.535 8 dB减小到5.80510-4 dB，大大地降低了光纤的连接损耗。新型光纤在小半径弯曲情况下，也能保证系统的传输质量。

Optimization design of bending performance for ultralow loss hole assisted fiber

A two-dimensional axisymmetric finite element model for fiber bending was established. The fiber bending performance was analyzed by finite element method. The fiber bending loss, the effective mode field area and the splice loss were calculated respectively. The multi-objective orthogonal optimization was combined with gray relational analysis method in the design for fiber bending performance which was carried out taking the bending loss and splice loss as objective functions, taking the distance b from the core to the trench, the width of trench c, the depth of trench t and the radius of air holes r as design variables. The results show that the bending loss of optimized fiber decreases from 0.127 8 dB/m to 1.749 810-4 dB/m, the effective mode field area of optimized fiber decreases from 94.741 m2 to 82.37 m2, the splice loss of optimized fiber reduces from 0.174 3 dB to 5.80510-4 dB. Compared with the standard single-mode fiber, it is found that the effective mode area of the proposed fiber decreases from 209.21 m2 to 82.3 m2 with the bend radius of 3 mm and the splice loss decreases from 7.535 8 dB to 5.80510-4 dB. The proposed fiber can also ensure the transmission quality of the system in the case of small bending radius.