We theoretically analyze plasmonic gap-mode nanocavities covered by a thick cladding layer at telecommunication wavelengths. In the presence of high-index cladding materials such as semiconductors, the first-order hybrid gap mode becomes more promising for lasing than the fundamental one. Still, the significant mirror loss remains the main challenge to lasing. Using silver coatings within a decent thickness range at two end facets, we show that the reflectivity is substantially enhanced above 95 %. At a coating thickness of 50 nm and cavity length of 1.51 μm, the quality factor is about 150, and the threshold gain is lower than 1500 cm(-1).
Abstract-In this paper, we investigate the effect of cladding layers on a hybrid plasmonic nanowire cavity. A decent confinement factor and moderate modal loss can be achieved for lasing. Within a certain index range of the cladding layer, the fundamental hybrid plasmonic mode is well confined inside the narrow gain region and becomes the most promising lasing mode. Our results also indicate that the mirror loss can be reduced if the refractive index of the cladding layer is properly chosen. An estimated cold-cavity quality factor of 87, corresponding to a threshold gain of about 1072 cm −1 , is achievable at a cavity length of 10.13 μm for the lasing mode.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.