Some aspects of polaritons and plasmons in materials

We have studied the interaction of optical phonons with photons. So, we have calculated the coupled modes of photons and transverse optical phonons and likewise, the dielectric function. We have found an alternative relation of the splitting between the frequencies of the longitudinal optical (LO) and transverse optical (TO) phonons in crystals. Likewise, we have studied the plasmon resonance frequency. We have determined the phonon–photon and the plasmon–photon coupling constant in ionic crystals and in metals, respectively, which is very close to the elastic force constant, and we have evaluated the bulk modulus. Further we have applied these results to tetrahedrally bonded III–V semiconductors.