Fig. 2: Polarization behaviour of a polariton pulse excited resonantly to the TE dispersion branch.

a Dispersion of two spin-split polariton modes \(\hbar \omega _{{\text{TE}},{\text{TM}}}(k,r_0)\) at position r₀ = 70 μm. The origin zero energy corresponds to \(\hbar \omega (0,0)\). The red blurry spot indicates the position and schematic spectral distribution of the probe pulse. The probe pulse of 5-ps duration is resonant to the TE polariton mode, i.e., k_p = k_t and ω_p = ω₀ at r₀. The inset schematically shows the orientation in real space of the effective magnetic field Ω(k) (grey arrows) and the pseudospin of polaritons belonging to the TE (blue arrows) and TM (red arrows) branches. b Trajectories on the Poincaré sphere of the Stokes vector characterizing polarization of the polariton pulse for different polarizations of the probe pulse (indicated in the panel). The black arrows indicate the direction with respect to the evolution in time. c Evolution of the intensity and d–f polarization components of the polariton pulse. g Time-integrated spatial distribution of the normalized intensity and h–j polarization components of the polariton pulse. The polarization of the probe pulse is taken as right circular for (c)–(j)