Resonant-tunnelling-assisted crossing for subwavelength plasmonic slot waveguides

Sanshui Xiao,Niels A Mortensen

doi:10.1364/oe.16.014997

Abstract

We theoretically investigate properties of crossing for two perpendicular subwavelength plasmonic slot waveguides. In terms of symmetry consideration and resonant-tunnelling effect, we design compact cavity-based crossing structures for nanoplasmonic waveguides. Our results show that the crosstalk is practically eliminated and the throughput reaches the unity on resonance. Simulation results are in agreement with those from coupled-mode theory. Taking the material loss into account, the symmetry properties of the modes are preserved and the crosstalk remains suppressed, while the throughput is naturally lowered. Our results may open a way to construct nanoscale crossings for high-density nanoplasmonic integration circuits.

Highlights

It is of great interest for guiding light at deep subwavelength scales in optoelectronics, partly because it may enable ultra-density integration of optoelectronic circuits
The propagation constant β (= βR + jβI) of surface plasmon polaritons can be obtained by solving the dispersion equation: ε1 p εmk ex p(kw) ex p(kw) where k and p, the functions of β, are the wave numbers of Surface plasmon polaritons (SPPs) in dielectric and metal, respectively, ε1 and εm are the dielectric constants of the medium in guide region and metals, respectively, and w is the width of the waveguide
Numerical results are calculated by finite-element method (FEM) in frequency domain, which agree well with those from the coupled-model theory

Summary

Introduction

It is of great interest for guiding light at deep subwavelength scales in optoelectronics, partly because it may enable ultra-density integration of optoelectronic circuits. Surface plasmon polaritons (SPPs) waveguides, which utilize the fact that light can be confined at metal-dielectric interface, have shown the potential to guide and manipulate light at deep subwavelength scales[5, 6, 7, 8, 9, 10, 11, 12]. Waveguide crossings require low intersection loss, low crosstalk, and compact dimensions. Several designs have been proposed for low-loss, low-crosstalk crossing of silicon-on-insulator nanophotonic waveguides [13, 14, 15]. We analysis the intersection loss of nanoplasmonic waveguide and design compact intersections with no crosstalk, based on resonant tunnelling effect. Except for the dispersion of the SPP waveguide, the calculations mentioned below are performed by the finite-element method (FEM) in frequency domain

Dispersion of surface plasmon polariton waveguide

Direct crossing for two perpendicular plasmonic waveguides

Findings

Summary