Studies of the Dispersion Relation of the Z1,2 Exciton-Polaritons in CuBr by the Two-Photon-Resonant Raman Scattering

Dispersion relations of the multicomponent Z 1,2 exciton-polaritons for K //[111] and K //[110] are determined by the two-photon-resonant Raman scattering via the excitonic molecule state, and there appears the significant anisotropy between them. These polariton dispersions are self-consistently analyzed by the theoretical forms of the symmetry-breaking effect due to a finite wave vector, where the K -linear, the heavy- and light-mass, and the warping effects are confirmed. The effective mass of the lowest molecular state is determined.