  We study the light scattering by plasmonic and dielectric symmetric trimers
to investigate the existence of polarization-independent Fano resonances.
Plasmonic hybridization theory is revealed to hide simple physics, and we
instead provide a simplified model for hybridization to derive a plasmonic
trimer's eigenmodes analytically. This approach is demonstrated to accurately
recreate full wave simulations of plasmonic trimers and their Fano resonances.
We are subsequently able to deduce the grounds for modal interference in
plasmonic trimers and the related formation of Fano resonances. However, by
taking advantage of the generality of our simplified hybridization approach, we
are also able to investigate the eigenmodes of all-dielectric trimers. We show
that bianisotropic coupling channels between high-index dielectric
nanoparticles are able to increase the capacity for Fano resonances, even at
normal incidence. We finally provide the first experimental measurements of
sharp, polarization-independent Fano resonances from a symmetric all-dielectric
trimer, with very good agreement to the predicted response from our simplified
hybridization theory.
