Investigation of plasmonic waveguides for strong confinement and long-range propagation

Abstract

Electronics can be fabricated at nm-scale dimensions and a high level of integration on a single chip. However, electronics is limited in speed by heat generation and interconnect delay time issues to about 10 GHz. Photonics can provide ultrafast data rates but it is limited in size by the fundamental laws of diffraction. Plasmonics offers the ability to combine the size of electronics and the speed of photonics by using Surface plasmon polaritons that are the result of interaction between the surface plasmon and the external electromagnetic field. In this thesis, we have designed waveguides using Channel plasmon polaritons (CPP) and hybrid plasmonic modes. First, we have investigated the upside-down channel plasmon polariton waveguide. This waveguide can be fabricated with KOH anisotropic wet etching and selective dry etching. And we have calculated the distribution of field intensity, the effective index, propagation length and mode area of CPP mode in the waveguide using FEM (Finite-element Method) tool. We have obtained that the mode becomes strongly confined as the gold film is thinner and the top apex angle becomes sharper. Second, we have investigated the hybrid long-range plasmonic waveguide. This waveguide uses a slot effect to confine the field in narrow region filled a material with low permittivity and has longer propagation length. The fabrication is simple by using e-beam lithography, dry etching and thin film deposition with Au, Er2O3 films and SOI wafer. We have calculated the effective index, propagation length, mode area and confinement factor of hybrid long-range plasmonic mode in the waveguide using FEM and FDTD (Finite-Different Time-Domain) method by changing the thickness of Au and Er2O3 layers. We have obtained that the propagation length ~0.88mm, mode area ~0.04 and confinement factor ~0.89 respectively.