Is there such a thing as a bare polariton?

Question

When dealing with photons in matter, I have seen it treated in many ways depending on the material, this leads to exciton polaritons (when dealing with electrons and holes), plasmaritons (dealing with plasma density waves) and phonon polaritons (coupling to lattice vibrations), magnon polaritons (to spin waves) and so on. However is there such a thing as just a bare polariton (not related to other quasiparticles)? In which kind of materials is it relevant? Is it the same as an uncoupled photon?

Would photons in an ideal transparent media with index $n\neq 1 $ be considered polaritons? Or are we always explicitly assuming that if $n\neq1$ photon interact with other quasiparticles so they must be called polariton-[insert quasiparticle here]?

Answer 1

Term polariton was coined in image of term polaron, which is by definition an electron dressed by photon cloud - i.e., and excitation of an electron-phonon system:

A polaron is a quasiparticle used in condensed matter physics to understand the interactions between electrons and atoms in a solid material. The polaron concept was proposed by Lev Landau in 19331 and Solomon Pekar in 1946[2] to describe an electron moving in a dielectric crystal where the atoms displace from their equilibrium positions to effectively screen the charge of an electron, known as a phonon cloud. This lowers the electron mobility and increases the electron's effective mass.

There is some ambiguity about what is defined as polariton, since different fields use this term to denote different things. The definition used in Wikipedia is the one coming from quantum optics and Bragg lattices:

In physics, polaritons are quasiparticles resulting from strong coupling of electromagnetic waves with an electric or magnetic dipole-carrying excitation.

In this sense polarons and polaritons are different from conduction electrons, holes, plasmons, phonons, magnons, etc. - the latter group represents quasiparticles arizing from quantization of the respective fields, whereas polaritons and polarons are by definition composit particles, resulting from the interaction of two (or more) fields.