  Active nanophotonic materials that can emulate and adapt between many
different spectral profiles -- with high fidelity and over a broad bandwidth --
could have a far-reaching impact, but are challenging to design due to a
high-dimensional and complex design space. Here, we show that a metamaterial
network of coupled 2D-material nanoresonators in graphene can adaptively match
multiple complex absorption spectra via a set of input voltages. To design such
networks, we develop a semi-analytical auto-differentiable dipole-coupled model
that allows scalable optimization of high-dimensional networks with many
elements and voltage signals. As a demonstration of multi-spectral capability,
we design a single network capable of mimicking four spectral targets
resembling select gases (nitric oxide, nitrogen dioxide, methane, nitrous
oxide) with very high fidelity (${>}\,90\%$). Our results are relevant for the
design of highly reconfigurable optical materials and platforms for
applications in sensing, communication and display technology, and signature
and thermal management.
