Dephasing of Excitonic Polaritons Confined in GaAs Thin Films

We report the dephasing of excitonic polaritons due to propagation in GaAs thin films measured using a reflection-type pump–probe technique. The rise time of the transient signal due to the propagation of excitonic polaritons decreases with an increase in temperature. This decrease originates from the dephasing of excitonic polaritons. From the analysis based on exciton–phonon scattering, the interaction with optical phonons mainly characterizes the dephasing process of exciton polaritons. Moreover, the result of the comparison of the temperature dependence of the damping factor estimated from the rise time with that estimated from the photoluminescence width indicates that an interaction with optical phonons in the propagation process is larger than that in the momentum relaxation process.