Xu Ji, Shi Nannan, Chen Yilin, Lu Xinyi, Wei Hongyu, Lu Yunqing, Liu Ning, Zhang Baifu, Wang Jin
Appl Opt. 2018 May 20;57(15):4043-4047. doi: 10.1364/AO.57.004043.
This study reports on a cylindrical hybrid plasmonic waveguide (CHPW) consisting of a high-index dielectric core, a sandwiched low-index dielectric layer, and a metal cladding. The CHPW supports the TM mode with a radially polarized transverse component of the electric field. Optical fields can be significantly enhanced in the sandwiched low-index dielectric region with nanoscale thickness down to 5 nm, and tight mode confinement with the same order of the normalized mode area compared with that of the plasmonic waveguide is achieved. Moreover, the mode propagation loss is well compensated by adjusting dimensions of the waveguide to obtain a longer propagation distance. The calculated figure of merit reaches a value several times greater than that in the similarly reported structure. The results indicate that this novel type of hybrid structure can support the limited propagation of a radially polarized mode with good confinement and low loss, consummate the whole system of manipulating the cylindrical vector beams, and show great potential of applications for various integrated nano-photonic devices.
本研究报道了一种由高折射率介质芯、夹在中间的低折射率介质层和金属包层组成的圆柱形混合等离子体波导（CHPW）。CHPW支持具有径向极化电场横向分量的TM模式。在厚度低至5nm的纳米级夹在中间的低折射率介质区域中，光场可以得到显著增强，并且与等离子体波导相比，实现了具有相同归一化模式面积量级的紧密模式限制。此外，通过调整波导尺寸来补偿模式传播损耗，以获得更长的传播距离。计算得出的品质因数达到的值比类似报道结构中的值大几倍。结果表明，这种新型混合结构可以支持具有良好限制和低损耗的径向极化模式的有限传播，完善了操纵圆柱矢量光束的整个系统，并显示出在各种集成纳米光子器件中的巨大应用潜力。
