  Selecting nanocomposites for photonic switching applications requires
optimizing their thermal, nonlinear and two-photon absorption characteristics.
We simplify this step by defining a compound figure of merit (FOM_{C}) for
nanocomposites of noble metals in dielectric based on criteria that limit these
structures in photonic applications, i.e. thermal heating and two-photon
absorption. The device independent results predict extremely large values of
FOM_{C} for a specific combination of the metal and insulator dielectric
constant given by \epsilon_{h}=\frac{\epsilon_{1}-\epsilon_{2}}{2}, where
\epsilon_{h} is the dielectric constant of the host and \epsilon_{1} and
\epsilon_{2} are the real and imaginary parts for the metal.
