Graphene-enhanced hybrid plasmonic nanolaser with an ultra-high figure of merit for refractive index sensing.

Hybrid plasmonic nanolasers have attracted significant attention as active sensing platforms that combine strong optical field confinement with coherent light generation beyond the diffraction limit. In this study, we propose a hybrid graphene-CdS plasmonic nanolaser for highly sensitive refractive index sensing. The device integrates a CdS nanowire with a multilayer silica aerogel/graphene/silica stack, forming a hybrid plasmonic cavity that supports strong plasmon-exciton coupling and low-loss optical feedback. Finite element simulations demonstrate a narrow linewidth of 5.8 nm, a high quality factor of 530, and a high sensitivity of 1324 nm/RIU, yielding a figure of merit (FOM) of 228 RIU-1. Compared with previously reported plasmonic and nanolaser-based sensors, the proposed design exhibits a substantial enhancement in both sensitivity and detection resolution. These results highlight the potential of graphene-assisted hybrid plasmonic systems for real-time, label-free biochemical and environmental sensing applications, paving the way toward ultra-compact, tunable, and energy-efficient optical sensors.