  Exciton-polariton solitons are strongly nonlinear quasiparticles composed of
coupled exciton-photon states due to the interaction of light with matter. In
semiconductor microcavity systems such as semiconductor micro and nanowires,
polaritons are characterized by a negative mass which when combined with the
repulsive nonlinear exciton-exciton interaction, leads to the generation of
bright polariton solitons. In this work we investigate the dynamics of bright
exciton-polariton solitons in a finite-size microcavity waveguide, for which
radiative losses are assumed balanced by the external pumping. An exact
bright-soliton solution to the model equations of motion, consisting of a
periodic train of polariton pulses, is obtained in terms of Jacobi elliptic
functions. Exact analytical expressions corresponding to the energies of both
photonic and excitonic components of the pulse train are found. Results suggest
that the size (i.e. the length) of a microwire waveguide plays a relevant role
in obtaining a quantitative estimate of the energy that could be conveyed by
polariton solitons propagating in the medium.
