S. I. Novikov

Polariton multistability and fast linear-to-circular polarization conversion in planar microcavities with lowered symmetry

The multistability of cavity-polariton systems with lowered symmetry (e.g., in laterally strained microcavities) allows implementing a few picoseconds long switching from linear to almost circular polarization of the cavity transmission under a resonant linearly polarized optical pump with slowly changing intensity. This effect has been observed in a high-Q GaAs microcavity using spectrally narrow 70 ps long pump pulses.

Bistability and nonequilibrium transitions in the system of cavity polaritons under nanosecond-long resonant excitation

The polarization dependence of nonequilibrium transitions in a multistable cavity-polariton system is studied under a nanosecond long resonant optical excitation at the normal and magic angle incidences with various polarizations of the pump beam. The temporal correlations between the frequency, intensity, and optical polarization of the intra-cavity field, which all undergo sharp threshold-like changes due to the spin dependent interaction of cavity polaritons, are visualized. The observed dynamics cannot be reproduced within the conventional semi-classical model based on the Gross-Pitaevskii equations. To explain the observed phenomena, it is necessary to take into account the unpolarized exciton reservoir which brings on additional blueshift of bright excitons, equal in the

Bose-einstein condensation of exciton polaritons in high-Q planar microcavities with GaAs quantum wells

\sigma^+

Transient spectroscopy of near-condensate modes in the system of exciton polaritons in a semiconductor microcavity

and

Spin dynamics of a vortical condensate of exciton polaritons in a GaAs microcavity

\sigma^-

Effect of the modulation of the polariton potential on the polarization instability of stimulated polariton-polariton scattering in planar gaas microcavities

polarization components. This model explains the effect of polarization instability under both pulsed and continuous wave resonant excitation conditions, consistently with the spin ring pattern formation that has recently been observed under Gaussian shaped excitation.

Effect of Coulomb interaction on exciton-polariton condensates in GaAs pillar microcavities

Condensation of exciton polaritons in planar microcavities with GaAs/AlAs quantum wells in the active area has been studied. It has been found that an increase in the lifetime of polaritons up to ∼10–15 ps when the Q factor of a microcavity exceeds 7000 makes it possible to detect Bose-Einstein condensation of polaritons with a dominant (>90%) photon component. Condensation occurs under thermodynamically nonequilibrium conditions in lateral traps with diameters ∼10 μm formed due to long-range fluctuations of the polariton potential. The violet shift of the polariton emission line at the condensation threshold significantly exceeds the energy of the repulsive interaction between polaritons in the condensate. It has been shown that the shift is mainly due to a decrease in the oscillator strength of bright excitons in lateral traps, caused by the localization of photoexcited long-living dark excitons.

Spin and density patterns of polariton condensates resonantly excited in strained planar microcavities with a nonuniform potential landscape

A transient spectroscopy technique for studying near-condensate modes of exciton polaritons in high-quality-factor planar semiconductor microcavities is proposed. It is demonstrated that, under the conditions of coherent external pumping, the transition to the upper steady state of an optically bistable condensate is accompanied by the excitation of near-condensate modes. They manifest themselves in the appearance of transient oscillations of the polariton intensity as the system switches to the upper branch of the S-shaped bistable pump dependence of the intensity. Analysis of the time-resolved spectra of these oscillations provides information on interactions in the system and the evolution of the exciton-polariton condensate density.

Nonlinear route to intrinsic Josephson oscillations in spinor cavity-polariton condensates

The temporal dynamics of a spinor exciton-polariton condensate in a high-quality anisotropic GaAs microcavity under pulsed resonant excitation with light possessing a nonzero orbital angular momentum is investigated. The phenomenon of spatial separation of the spin components of the polariton condensate upon pumping with a coherent superposition of two beams with opposite circular polarizations and orbital angular momenta is observed. The key factors for the observation of this effect are the lateral anisotropy of the microcavity that causes a splitting between the linear components of the polariton ground state and the occurrence of opposite orbital angular momenta for the two spin components of the condensate. The experimental results are in qualitative agreement with the theoretical model of the phenomenon developed in JETP Lett. 104, 827 (2016).

Loss of coherence in cavity-polariton condensates: Effect of disorder versus exciton reservoir

The polarization characteristics of the stimulated polariton-polariton scattering signal under resonance excitation in the vicinity of the inflection point of the polariton dispersion curve are investigated in the absence and in the presence of exciton-potential modulation imposed by a surface acoustic wave. It is found that the spatial modulation of the exciton potential leads to an abrupt decrease in the effective critical pump density above which the polarization of the scattering signal changes. This opens the way for the use of acoustic waves to control the polarization of the stimulated scattering signal in polariton systems.