Random lasing based on a nanoplasmonic hybrid structure composed of (Au core)-(Ag shell) nanorods with Ag film

Metallic films are widely used as electrodes in micro-cavities. However, the quenching effect of metal films is generally considered fatal for lasing, and presents a major obstacle to the development of electrically pumped lasers. In this article, we report on the dramatic performance enhancement of random lasing assisted by a plasmonic hybrid structure composed of (Au core)-(Ag shell) nanorods deposited on Ag film (Au@Ag NRs-Ag film). This study reveals that the Au@Ag NRs-Ag film hybrid structure can more effectively enhance the lasing properties than independent Au@Ag NRs or Ag film. Besides, compared with hybrid structures composed of Ag film with Au nanorods or Au nanospheres, the gain medium deposited on Au@Ag NRs-Ag film has the lowest lasing threshold: only 12.5% of that of the neat gain medium. As a unique plasmonic hybrid nanostructure, Au@Ag NRs-Ag film exhibits a stronger localized electrical field and scattering effect than the hybrid structures composed of Ag film with regular Au nanoparticles. This is attributed to the broader and stronger plasmonic absorption of Au@Ag NRs, as well as to the stronger plasmonic coupling between the localized surface plasmons of Au@Ag NRs and the delocalized surface plasmon polariton of Ag film. Our results could provide a simple way to effectively avoid the negative effects of metal films and realize a lower pumped threshold.