Polariton spin beats in semiconductor quantum well microcavities (original) (raw)
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Physical Review B, 2005
Microcavity polariton spin dynamics is investigated in high-finesse microcavities under resonant excitation using polarization-and time-resolved secondary emission spectroscopy. Using an appropriate calibration procedure, the instantaneous polariton occupation numbers of the modes with k Ϸ 0 wave vectors can be determined. When the phase-matching conditions are achieved, we show that Coulomb scattering dominates the other processes, and that stimulation occurs when the occupation of the k Ϸ 0 final state with a given mode polarization approaches unity. Under elliptically polarized light, we show that the stimulated polariton scattering leads to an increase with time of the circular polarization of the k Ϸ 0 states, while the linear polarization dynamics is characterized first by a fast drop to negative or zero values immediately after the excitation pulse, followed by weak-amplitude nonperiodic oscillations. The latter are interpreted as the manifestation of the pseudospin precession of the pumped polariton modes around the self-induced exchange effective field.
Motion of Spin Polariton Bullets in Semiconductor Microcavities
Physical Review Letters, 2011
The dynamics of optical switching in semiconductor microcavities in the strong coupling regime is studied by using time- and spatially resolved spectroscopy. The switching is triggered by polarized short pulses which create spin bullets of high polariton density. The spin packets travel with speeds of the order of 106m/s due to the ballistic propagation and drift of exciton polaritons from high to low density areas. The speed is controlled by the angle of incidence of the excitation beams, which changes the polariton group velocity.
Spin quantum beats in semiconductor microcavities in the strong coupling regime
2002
We have observed polariton spin quantum beats under transverse magnetic field and circular polarization excitation (Voigt configuration) by time-resolved photoluminescence spectroscopy. The temporal behaviour of the beats strongly differs depending on whether the excitation is resonant or not with the lower polariton branch. As in bare quantum wells, we show that this is the consequence of the hole spin instability under non-resonant excitation. In both cases, we evidence a dependence on the cavity detuning d of the electron effective Landé g-factor (g eff). This is attributed to strong coupling regime, where the bare electron Landé g-factor is depends on the polariton exciton component. All these characteristics are well described by a simplified model, which takes into account the transfer dynamics between two classes of polaritons.
Polariton spin dynamics in III-V semiconductor microcavities
Physica Status Solidi (c), 2005
Time resolved measurements have been performed on a III–V semiconductor microcavity in a two beam configuration. Resonant excitation of the lower polariton branch in the parametric amplification regime is provided by a CW laser impinging at 16.5º and the system is subsequently perturbed via a pulsed laser for different angles of incidence. The polarization state of the emission at k‖ = 0 is investigated for different polarization combinations of the CW and pulsed laser. We discuss the interplay between these beams in affecting the polariton spin dynamics. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Polariton Spinor Interactions in a GaAs-based microcavity
We report on spinor polariton interactions in GaAs based microcavity. This investigation is carried out by means of heterodyne polarized pump-probe spectroscopy. The results reveal the magnitude and the sign of interaction strength between polaritons with parallel and anti-parallel spins. We clearly show the dependence of the attractive and repulsive interaction constants with the cavity detuning. We evidence the strong influence of the biexciton resonance on the attractive interaction strength. Our modelization based on Gross-Pitaevskii equation reproduces the experimental observations. PACS numbers: 78.67. De, 71.36.+c Microcavity exciton polaritons are quasiparticles resulting from the strong coupling between excitons and photons . Polaritons exhibit mutual interactions coming from their excitonic content and light effective mass inherited from the photon. Moreover, the collected photons emitted from the cavity allow to read out the polaritons properties. As a matter of fact, a polariton fluid is an ideal tool for investigating quantum phenomena in solid-state systems. Polariton interactions in semiconductor microcavities play a crucial role in a wide variety of topics ranging from nonlinear optical effects, polariton superfluidity to Bose Einstein condensation. Their quantum coherence properties have been extensively investigated since the observation of polariton parametric processes [2-6]. First signs indicating spontaneous quantum degeneracy of polaritons appeared with the observation of stimulated emission under non-resonant excitation . In 2006, polariton Bose-Einstein condensation was demonstrated for the first time . Since then, many experiments have been performed to assess the superfluidity of polaritons, as well as the observation of full [10] and half quantized vortices, the demonstration of polariton flowing without scattering , and of solitons . The observation of the Bogoliubov excitations has been performed after initial indications of the linearization of the polariton dispersion .
Spin waves in semiconductor microcavities
Physical Review B
We show theoretically that a weakly interacting gas of spin-polarized exciton-polaritons in a semiconductor microcavity supports propagation of spin waves. The spin waves are characterised by a parabolic dispersion at small wavevectors which is governed by the polariton-polariton interaction constant. Due to spin-anisotropy of polariton-polariton interactions the dispersion of spin waves depends on the orientation of the total polariton spin. For the same reason, the frequency of homogeneous spin precession/polariton spin resonance depends on their polarization degree.
Anisotropic polariton scattering and spin dynamics of cavity polaritons
Solid State Communications, 2005
We describe the spin-dynamics of exciton-polaritons in semiconductor microcavities in the strong coupling regime. Using the Liouville equation for the spin-density matrix in the Born-Markov approximation we obtain kinetic equations taking into account polariton-acoustic phonon and polariton-polariton scattering. We describe both the 'polariton laser' regime (nonresonant excitation) and 'optical parametric oscillator' regime (resonant excitation at the magic angle). We obtain a good agreement with experimental data on the dynamics of polarization of light emitted by microcavities.
Polarization dependence of nonlinear wave mixing of spinor polaritons in semiconductor microcavities
Physical Review B, 2016
The pseudo-spin dynamics of propagating exciton-polaritons in semiconductor microcavities are known to be strongly influenced by TE-TM splitting. As a vivid consequence, in the Rayleigh scattering regime, the TE-TM splitting gives rise to the optical spin Hall effect (OSHE). Much less is known about its role in the nonlinear optical regime in which four-wave mixing for example allows the formation of spatial patterns in the polariton density, such that hexagons and two-spot patterns are observable in the far field. Here we present a detailed analysis of spin-dependent fourwave mixing processes, by combining the (linear) physics of TE-TM splitting with spin-dependent nonlinear processes, i.e., exciton-exciton interaction and fermionic phase-space filling. Our combined theoretical and experimental study elucidates the complex physics of the four-wave mixing processes that govern polarization and orientation of off-axis modes.
Quantum beats between light and dark polariton states in semiconductor microcavities
physica status solidi (c), 2004
We observe experimentally pronounced beats of the intensity of photoluminescence from a bottleneck region of a microcavity in the strong coupling regime. These beats are extremely sensitive to the pumping intensity and vanish for the weak pumping. We show theoretically that the process of polariton-polariton scattering leading to the mixing between bright and dark polariton states is responsible for this effect.
Spin quantum beats in CdMnTe microcavity
physica status solidi (c), 2005
CdMnTe quantum well embedded in CdMgTe/CdMnTe microcavity is studied by time-resolved Kerr rotation experiments under in-plane magnetic field and quantum beatings corresponding to at least three distinct frequencies are observed. Whereas the lowest gigahertz frequency is clearly identified with Mn spin precession in the quantum well, terahertz beatings can be due to both polariton formation and valence band states mixing in the magnetic field. However, the experiments indicate unambiguously that there is no beatings between coherently excited polariton states in the absence of magnetic field, in contrast with the proposed model, which predicts the beatings at Rabi frequency in zero field.