SPASER as a complex system: femtosecond dynamics traced by ab-initio simulations

Abstract

Integrating coherent light sources at the nanoscale with spasers is one of the most promising applications of plasmonics. A spaser is a nano-plasmonic counterpart of a laser, with photons replaced by surface plasmon polaritons and the resonant cavity replaced by a nanoparticle supporting localized plasmonic modes. Despite the large body of experimental and theoretical studies, the understanding of the fundamental properties of the spaser emission is still challenging. In this work, we investigated the ultrafast dynamics of the emission from a core-shell spaser by developing a rigorous first-principle numerical model. Our results show that the spaser is a highly nonlinear system with many interacting degrees of freedom, whose emission sustain a rich manifold of different spatial phases. In the regime of strong interaction we observed that the spaser emission manifests an irreversible ergodic evolution, where energy is equally shared among all the available degrees of freedom. Under this condition, the spaser generates ultrafast vortex lasing modes that are spinning on the femtosecond scale, acquiring the character of a nanoparticle with an effective spin. Interestingly, the spin orientation is defined by spontaneous symmetry breaking induced by quantum noise, which is a fundamental component of our ab-initio model. This opens up interesting possibilities of achieving unidirectional emission from a perfectly spherical nanoparticle, stimulating a broad range of applications for nano-plasmonic lasers as unidirectional couplers, random information sources and novel form of photonics neural-networks.

Anapole-Assisted Low-Power Optical Trapping of Nanoscale Extracellular Vesicles and Particles

“…Our proposed anapole nanotweezer (ANT) harnesses the optical anapole states to confine light to the nanoscale and generate an enhanced optical gradient force on nanoscale NVEPs. We note that optical anapoles are actively investigated for optoelectronic applications such as anapole lasers 26 and for second-harmonic generation 27 due to their highly enhanced fields. While nearfield optical trapping using anapole states have been theoretically proposed by us and others, no experimental demonstration has been reported to date.…”