A CW-Pumped Dye Nanolaser With an Optimized Nanocavity

Abstract

Plasmonic nanolasers, which are promising coherent light sources for integrated photonics, super-resolution imaging, and ultrasensitive sensing applications, face the challenge of high thresholds due to inherent losses in plasmonic nanocavities. While considerable efforts have been made to improve the Q factor, typically quantified by the full width at half maximum (FWHM), intensity (ΔI) is another critical feature of plasmonic resonance. However, the combined influence of both the Q factor and resonance intensity of a plasmonic nanocavity on nanolasing threshold has not been sufficiently explored, as experimentally controlling one variable while keeping the other constant is challenging. Here, an ultra-low threshold plasmonic nanolaser is demonstrated by systematically optimizing the plasmonic nanocavity. By carefully controlling both the FWHMs and resonance intensities of the plasmonic resonators, a record low threshold of 2.6 µJ cm⁻² for a dye-based nanolaser is achieved at room temperature– an order of magnitude lower than previous records. In addition, nanolasing under continuous-wave (CW) excitation is reported at room temperature gained by the same dye molecule. The results provide new insights into the design of high-performance plasmonic nanolasers and offer a promising path toward realizing applications of nanoscale coherent light sources.