Dynamics of Amplification and Lasing in Nano-Plasmonic Metamaterials

The talk will discuss the rich physics of amplification and lasing in nano-plasmonic metamaterials. Starting from fundamental electrodynamic and quantum-mechanical principles we introduce a rigorous theoretical model for the spatial and temporal interaction of light-waves with free and bound electrons inside and around metallic (nano-) structures and gain media. A unique 3D auxiliary-equation finite-difference time-domain (AE-FDTD) framework allows us to self-consistently study on the nano-scale the dynamics and impact of the coherent plasmon-gain interaction, nonlinear saturation, field enhancement, radiative damping and spatial dispersion. Using numerical pump-probe experiments on a nano-plasmonic (double-fishnet) metamaterial structure with dye molecule inclusions we investigate the build-up of the inversion profile and the formation of the plasmonic modes in the low-Q cavity. We find that full loss compensation may occur in a regime where thereal part of the effective refractive index of the metamaterial becomes morenegative compared to the passive case and identify a transition to lasing. Our results provide a deep insight into how dynamic internal processes affect the over-all optical properties of active photonic metamaterials revealing the fundamental physical properties of practical loss-compensated plasmonic nanostructures and nano-plasmonic lasers and fostering new approaches to aninnovative design.