Silicon Waveguides at the Mid-Infrared

In this paper, we propose a detailed study of various novel waveguides made using doped silicon at the mid-infrared (MIR) range. These waveguides support a plasmonic-like mode with nanoscale confinement in the MIR. We also demonstrate a simple mechanism for tuning the plasma resonance through controlling the doping level of silicon. Moreover, the dispersion characteristics of the doped silicon devices are analyzed for different applications at the MIR region. We also investigated various phenomenon such as negative dispersion, which can be utilized for slow light and metamaterial applications, and epsilon-near-zero characteristics that can be used for extraordinary transmission. The MIR dispersion is studied thoroughly for the slot structure and the rectangular shell structure. The potential for biological and environmental sensing for the aforementioned structures is investigated as well. In addition, we demonstrated the use of the waveguide as a slow light medium; this was facilitated as the dispersion relations reached giant values in the order of 10⁵ at the resonance.