Jeong Chang Yeong, Kim Myunghwan, Kim Sangin
Department of Electrical and Computer Engineering, Ajou University, Suwon 443-749, South Korea.
Opt Express. 2013 Jul 15;21(14):17404-12. doi: 10.1364/OE.21.017404.
We propose a novel plasmonic waveguide structure, which is referred to as a circular hybrid plasmonic waveguide (HPW) and consists of a metal wire covered with low- and high-index dielectric layers. The circular HPW exhibits two distinctly different modes, namely, the strongly localized mode and the extremely low-loss mode. Our numerical calculation demonstrates that the strongly localized mode exhibits 10 order scale in normalized mode area and can be performed even in tens of nanometer sizes of waveguide geometry. In the extremely low-loss mode, the HPW exhibits ultra-long propagation distance of more than 10μm that can be achieved by forming the dipole-like hybrid mode and properly adjusting the radius of the metal wire. It is also shown that, even with this long-range propagation, the mode area of the dipole-like hybrid mode can be maintained at subwavelength scale. The simultaneous achievement of a small mode area and ultra-long propagation distance contributes to the ultra-high propagation distance to mode size ratio of the waveguide. The HPW results are very helpful for plasmonic device applications in the fields of low-threshold nanolasers, ultrafast modulators, and optical switches.
我们提出了一种新型的等离子体波导结构，称为圆形混合等离子体波导（HPW），它由覆盖有低折射率和高折射率介质层的金属线组成。圆形HPW呈现出两种截然不同的模式，即强局域模式和极低损耗模式。我们的数值计算表明，强局域模式在归一化模式面积上呈现10阶规模，甚至在几十纳米尺寸的波导几何结构中也能实现。在极低损耗模式下，HPW通过形成偶极子状混合模式并适当调整金属线的半径，可实现超过10μm的超长传播距离。研究还表明，即使有这种长距离传播，偶极子状混合模式的模式面积也能保持在亚波长尺度。小模式面积和超长传播距离的同时实现有助于提高波导的传播距离与模式尺寸之比。HPW的结果对于低阈值纳米激光器、超快调制器和光开关等领域的等离子体器件应用非常有帮助。
