提出了一种新型超宽带双芯光子晶体光纤偏振分束器.应用全矢量有限元法,系统地研究了光纤结构参数对偏振分束器带宽和偏振分束器长度的影响.分析结果表明:增加掺氟区折射率,既能提高分束器带宽,也能减少分束器长度;增大光纤中空气孔的孔距及孔径与孔距比,可以增加分束器的带宽,但同时也会导致分束器的长度增大,使得器件尺寸增大.因此,在设计中需兼顾分束器的带宽和长度来选取光纤的结构参数.通过结构参数的优化,设计出一种短长度、高消光比和超宽带的偏振分束器,其长度为7.362 mm,消光比高于20 dB的带宽为600 nm.
A novel broadband polarization beam splitter(PBS) based on dual-core photonic crystal fiber is proposed. With a full-vector finite element method, the effects of structural parameters of fiber on the bandwidth and length of PBS are systematically investigated in detail. Numerical results indicate that an increase in the index of fluorine-doped region can not only broaden the bandwidth but also shorten the length of PBS. An increase in the diameters of air hole and hole pitch in an optical fiber can broaden the bandwidth of PBS, however, lengthen the length of PBS at the same time. Thus, it is necessary to balance the bandwidth and length of PBS when selecting the fiber structure parameters. Through optimizing the fiber structure parameters mentioned above, a kind of ultra-broadband PBS is achieved. When the extinction ratio is greater than 20 dB, the length of PBS is as short as 7.362 mm and its bandwidth is more than 600 nm.