Experimental Observation of Purcell-Enhanced Spontaneous Emission in a Single-Mode Plasmonic Nanocavity

Abstract

Fast and energy-efficient nanoscale light sources operating at the near-infrared (near-IR) spectral range are essential for next-generation optical interconnect and computation systems. Here, we report the experimental observation of ultrafast spontaneous emission enabled by the Purcell enhancement in an asymmetric coaxial plasmonic nanocavity, utilizing InGaAsP multiple quantum wells (MQW) as the optical gain material. By intentionally displacing the metal core from the center of the cavity, we break the cavity’s symmetry and achieve high Purcell factors attributed to the extremely small mode volume on the order of (0.02 × (λ0/n a)3). Notably, we achieve a measured shortest spontaneous emission lifetime of 24 ps, corresponding to a remarkably high Purcell factor of 74 and a modulation bandwidth of 6.65 GHz. This advancement marks a significant step toward the realization of on-chip nanoscale light sources for applications in the telecom regime.