Tunable synchronization and energy transport networks in plasmonic-dielectric nanoparticle assemblies

The collective optical response of plasmonic nanoparticle assemblies is described as a synchronization phenomenon. By mapping silver nanoparticles onto Kuramoto–Sakaguchi phase oscillators, we constrain their frequency and frustration phase to the system’s optical response rather than treating them as free parameters. In this model, co-dispersed carbon nanoparticles act as a multiplication factor and dielectric scatterers that amplify inter-particle coupling, lowering the synchronization threshold without shifting the intrinsic oscillator frequencies. Linear stability analysis reveals three additive routes to coherence: dielectric amplification, frequency detuning, and laser drive. Within the synchronized state, an active subgraph emerges where maximum-bottleneck paths dictate preferential energy-transport routes, yielding a percolation-type order parameter. In dense aggregates, asymmetrically placed mediators induce amplitude heterogeneity, rendering the reduced coupling non-reciprocal. This is predicted to produce a non-normal Jacobian that permits partial synchronization even at exact resonance. Finally, UV–vis spectroscopy of pulsed-laser-ablated AgC colloids is consistent with this theoretical mechanism, demonstrating that the plasmon band exhibits super-additive intensification as carbon content increases while maintaining a fixed spectral position.