A Plasmonic quantum dot nanolaser: effect of “waveguide Fermi energy” on material gain

Abstract

This work studies the gain from plasmonic quantum dot (QD) nanolaser. A metal/semiconductor/metal (MSM) structure was considered to attain plasmonic nanocavity with active region contains: 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. High net modal gain was obtained when the waveguide Fermi energy was taken into account which means that the increment comes from the material gain not from the confinement factor. The change in waveguide Fermi energy in the valence band explained the high gain, where the valence band QD states are fully occupied referring to an efficient hole contribution.