非对称大边孔微结构光纤偏振拍长稳定性的优化

Optimization of Polarization Beat-length Stability of the Microstructure Fiber with a Larger Asymmetric Hole Near the Core

针对纤芯一侧具有一个大边孔微结构光纤的特点,分别在两个正交方向上进行压缩或伸展,采用全矢量有限差分波束传播法模拟了不同压缩因子对应的双折射色散曲线,通过线性度最好的双折射色散曲线进一步限定压缩因子取值范围,较快地获得了偏振拍长最平坦的色散曲线,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1.0μm～2.0μm波长范围内,偏振拍长的相对变化率约为4.2%,带宽达到600nm,这种具有非对称大边孔微结构光纤适合制作宽带1/4波片.

A microstructure fiber with a larger asymmetric hole near the core is squeezed or expanded in orthogonal directions. The birefringence dispersion with different deformation factor is simulated by the full-vector finite-dif- ference beam propagation method. The range of the deformation factor is able to be further limited by the birefrin- gence dispersion curves. The most flat curve of polarization beat length is obtained quickly. A suitable expansion factor is found by optimizing the design. The wavelength sensitivity of polarization beat-length is effectively re- duced. The relative variation of polarization beat-length is about 4.2% and its bandwidth is up to 800nm over 1.0 ~ 2.0μm. This microstructure fiber is very suitable for making wideband fiber-optic quarter wave-plate.