  We analyse from a theoretical point of view the optical properties of arrays
of carbon nanotubes filled with silver. Dependence of these properties on the
different parameters involved is studied using a Transfer Matrix formalism able
to work with tensor-like dielectric functions and including the full
electromagnetic coupling between the nanotubes. We find these structures
exhibit very strong linear optical response and hence could be used as
spectroscopic enhancers or chemical sensors in the visible range. Very
localised surface plasmons, created by the electromagnetic interaction between
the capped silver cylinders, are responsible of this enhancing ability.
Enhancements of up to $10^6$ in the Raman signal of molecules absorbed on these
arrays could be obtained.
