in 1929. Polaritons were first considered theoretically by Kirill Borisovich Tolpygo. They were termed light-excitons in Soviet scientific literature. That name was suggested by Solomon Isaakovich Pekar, but the term polariton, proposed by John Hopfield, was adopted.

Coupled states of electromagnetic waves and phonons in ionic crystals and their dispersion relation, now known as phonon polaritons,