Giant Net Modal Gain of plasmonic quantum dot nanolaser

This work studies the net modal gain from plasmonic quantum dot (QD) nanolaser. A metal/semiconductor/metal (MSM) structure was considered to attain plasmonic nanocavity with active region contains: QDs, 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. Giant 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 net modal gain, where the valence band QD states are fully occupied referring to an efficient hole contribution. (paper)