Plasmonic enhanced lasers of nano-colloidal fluids
  Localized surface plasmon resonances have recently attracted considerable attention due to their ability to dramatically enhance near-field optical intensities and boost nanoscale light-matter interactions. Here we demonstrate unambiguously that polyhedral silver nanoparticles can be tailored to promote enhanced coherent emission from organic dye dispersions in a cavity. In particular, we observe that nanoparticles supporting resonances close to the absorption peak of the dye yield to more efficient lasing, up to one order of magnitude, which is also evidenced by the narrowing of the emission spectral line down to 3 nm. Moreover we observe emission saturation and energy dependent spectral shifts associated with Kerr effects, which demonstrate the general relevance of non-resonant nonlinearities in plasmonic enhanced laser emissions. Works in this area will contribute to the design of novel kind of laser sources providing ultra-short pulsed operation and structural tunability. 
Neda Ghofraniha, Pascal Andr\`e, Andrea Di falco and Claudio Conti
physics.optics cond-mat.soft