  In this paper we theoretically show that the Raman scattering by a core-shell
micron or submicron particle with epsilon-near-zero metamaterial shell and
silica spherical or cylindrical core can combine useful features of
cavity-enhanced and surface-enhanced Raman scattering. The cavity resonance
together with the plasmon resonance lead to the giant enhancement of the field
inside the metashell which is performed as a layer of silver or gold
nanoparticles and is penetrable for molecules to be detected. This approach
results in the significant increase of both effective volume in which molecules
are affected by enhanced electric field and Raman gain averaged over this
volume.
