Numerical Analysis of a GaAs-Based Hybrid Plasmonic Waveguide with Nanoscale Optical Confinement and Low Losses

Abstract

A numerical analysis of a hybrid plasmonic waveguide (HPW) for deep subwavelength optical confinement and long-range propagation with low loss is presented here. Two types of material platforms, namely, Si/SiO2/Au and GaAs/SiO2/Ag, were analyzed to optimize the HP waveguide. The mode character, an important and crucial design parameter for HP waveguides, was calculated based on the coupled mode theory, providing the coupling strength between the SPP and optical mode. As for the Si/SiO2/Au HP waveguide, the coupling strength varied from 0.47 to 0.60 with a mode area ranging from 0.0002/μm2 to 0.001/μm2 and mode character near to the SPP mode character (i.e., |a+(tsi, w, td)|= 0.47). While for the GaAs/SiO2/Ag HP waveguide, the coupling strength varied from 0.57 to 0.69 with a mode area ranging from 0.0002/μm2 to 0.0004/μm2 and mode character to SPP approached as |a+(tGaAs, w, td)|= 0.49. Finally, a finite element method (FEM) model was used to investigate the modal properties. The simulation analysis shows that at td = 10 nm the GaAs/SiO2/Ag waveguide gives 50% larger propagation length (205 μm), ten times smaller mode area (0.0002) with 60% lower modal propagation loss (0.021 db/μm), and 20% stronger coupling strength (0.62) with HPP mode character as 0.48 as compared to Si/SiO2/Au.