  Metamaterials, artificial media structured on the subwavelength scale offer a
rich paradigm for developing unique photonic functionalities ranging from
negative index of refraction and directionally asymmetric transmission to
slowing light. Here we demonstrate that a combination of carbon nanotubes with
a photonic metamaterial offers a new paradigm for the development of nonlinear
media with exceptionally strong ultrafast nonlinear response invaluable in
photonic applications. It is underpinned by strong coupling between weakly
radiating Fano-type resonant plasmonic modes and the excitonic response of
single-walled semiconductor carbon nanotubes. Using a "combinatorial" approach
to material discovery we show that the optical response of such a composite
system can be tailored and optimized by metamaterial design.
