  In the context of field theory in curved spacetimes, it is known that
suitable background spacetime geometries can trigger instabilities of fields,
leading to exponential growth of their (quantum and classical) fluctuations ---
a phenomenon called $\textit{vacuum awakening}$ in the quantum context, which
in some classical scenarios seeds $\textit{spontaneous
scalarization/vectorization}$. Despite its conceptual interest, an actual
observation in nature of this effect is uncertain since it depends on the
existence of fields with appropriate masses and couplings in strong-gravity
regimes. Here, we propose analogues for this gravity-induced instability based
on nonlinear optics of metamaterials which could, in principle, be observed in
laboratory.
