Angle resolved spectroscopy of polariton stimulation under non-resonant excitation in CdTe II-VI microcavity

We present some experimental study of CdTe II-VI microcavity polaritons generated by strong non-resonant optical excitation. We first compare spectra of luminescence under high excitation and white light reflectivity showing that the polariton stimulation occurs in the strong coupling regime. In a second part we present a measurement of the integrated polariton emission intensity versus the excitation power: the stimulated emission exhibits an exponential behaviour which excludes a polariton/polariton quadratic collision process. In a third part we present an angle-resolved experiment showing that the stimulation peak is dispersion free while the residual spontaneous emission keeps its usual dispersion curve; we exclude a simple scattering phenomenon due to surface roughness and discuss the possibility of real space shrinkage or polariton collisions within a coherent population inspired by the theoretical work of Ciuti and co-workers