Plasmonic Quantum Dot Nanolaser: Effect of 'Waveguide Fermi Energy'

This study models quantum dot (QD) plasmonic nanolaser. A metal/semiconductor/metal (MSM) structure was considered to attain plasmonic nanocavity. The active region (semiconductor layers) contains the following: QD, wetting layer (WL), and barrier layers. Band alignment between layers was used to predict their parameters. Momentum matrix element for transverse magnetic (TM) mode in QD structure was formulated. Waveguide Fermi energy was introduced and formulated, for the first time, in this work to cover the waveguide contribution (Ag metal layer) in addition to the active region. The high net modal gain was obtained when the waveguide Fermi energy was considered which meant that the increment comes from the material gain, not from the confinement factor. The obtained results were reasoned the high gain due to the change in waveguide Fermi energy in the valence band, where the valence band QD states are fully occupied that are referring to an efficient hole contribution.