Enhanced lasing assisted by the Ag-encapsulated Au plasmonic nanorods.

Threshold reduction and emission enhancement were reported for the waveguided random lasing, assisted by the Ag-encapsulated Au nanorods (Au@Ag NRs). The blend of tris(8-hydroxyquinolinato)aluminum (Alq₃) and 4-(dicyanomethylene)-2-tert-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4 H-pyran (DCJTB), which comprise the typical donor-acceptor lasing system, is used as the gain media. Compared with the Ag nanoparticles and Au nanorods, Au@Ag NRs exhibited the broad absorption spectra of localized surface plasmon resonance (LSPR) with multiple peaks, which sufficiently overlapped with both absorption and emission spectra of the donor-acceptor system of the gain media. This unique plasmonic characteristic of Au@Ag NRs leads to the lower lasing threshold and enhances the lasing efficiency by the effects of both enhancement of localized electromagnetic field and scattering.