  Self-assembly processes provide the means to achieve scalable and versatile
metamaterials by "bottom-up" fabrication. Despite their enormous potential,
especially as a platform for energy materials, self-assembled metamaterials are
often limited to single phase systems, and complex multi-phase metamaterials
have scarcely been explored.We propose a new approach based on sequential
self-assembly that enables the formation of a two-phase metamaterial composed
of a disordered network metamaterial with embedded nanoparticles. Taking
advantage of both the high-spatial and high-energy resolution of electron
energy loss spectroscopy, we observe inhomogeneous localization of light in the
network, concurrent with dipolar and higher-order localized surface plasmon
modes in the nanoparticles. Moreover, we demonstrate that the coupling strength
deviates from the interaction of two classical dipoles when entering the strong
coupling regime. The observed energy exchange between two phases in this
complex metamaterial, realized solely through self-assembly, implies the
possibility to exploit these disordered systems for plasmon-enhanced catalysis.
