IOP PUBLISHING JOURNAL OF OPTICS J. Opt. 15 (2013) 035503 (9pp) doi:10.1088/2040-8978/15/3/035503 Hybrid plasmonic waveguide incorporating an additional semiconductor stripe for enhanced optical confinement in the gap region Yusheng Bian 1 , Zheng Zheng 1 , Xin Zhao 1 , Lei Liu 1 , Yalin Su 1 , Jiansheng Liu 1 , Jinsong Zhu 2 and Tao Zhou 3 1 School of Electronic and Information Engineering, Beihang University, Beijing 100191, People’s Republic of China 2 National Center for Nanoscience and Technology, No.11 Zhongguancun Beiyitiao, Beijing 100190, People’s Republic of China 3 Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102, USA E-mail: zhengzheng@buaa.edu.cn Received 13 September 2012, accepted for publication 11 January 2013 Published 4 February 2013 Online at stacks.iop.org/JOpt/15/035503 Abstract A hybrid plasmonic waveguide consisting of a thin high-index dielectric stripe embedded inside the gap between a metallic substrate and a semiconductor ridge is presented for the purpose of enhanced optical confinement in the gap. By engineering the key geometrical parameters of the stripe, both of the power ratios resided inside the whole gap and the silicon ridge can be enhanced greatly. A power confinement ratio as large as 0.54 in the overall gap region is achievable, for a structure with a 200 nm-wide, 90 nm-thick silicon-stripe embedded in the center of a 100 nm-thick silica gap, which is nearly 50% improvement over that of the corresponding conventional hybrid waveguide. Meanwhile, with the introduction of the 90 nm-thick silicon stripe, the effective mode area of the waveguide exhibits a reduction of 50%–60% with a reasonable propagation length around 25–65 μm for different stripe widths. A study on the influence of possible fabrication imperfections reveals that the modal property is quite robust and highly tolerant to these errors. Such a hybrid plasmonic waveguide with enhanced optical confinement and moderate modal loss may enable the realization of ultra-compact passive components, nanolasers with low pumping thresholds, and other potential applications. Keywords: waveguide, surface plasmon, integrated photonics (Some figures may appear in colour only in the online journal) 1. Introduction Surface plasmons (SPs) have been regarded as the key to break down the fundamental diffraction limit in conventional photonics systems, as they offer the unique potential to guide and route light at the truly nanometer scale [1]. Along with other attractive properties, such as simultaneously supporting the transmission of light and delivering electric signals through the same chip [2], strong local field enhancement that induces high sensitivity against an index change near metallic surfaces [3], they offer unprecedented opportunities for a number of interesting applications and hold great promise for the realization of on-chip integrations of electronic and photonic components in the 1 2040-8978/13/035503+09$33.00 c  2013 IOP Publishing Ltd Printed in the UK & the USA