Excitonic Nonlinearities of Semiconductor Microcavities in the Nonperturbative Regime (original) (raw)
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We investigate a GaAs/͑Ga,Al͒As Fabry-Pérot microcavity, into which ͑In,Ga͒As quantum wells have been inserted. The cavity is wedge shaped, i.e., the detuning between the bare-exciton resonance and the bare optical cavity mode depends on the spatial position on the sample. Linear transmission spectra reveal a well-resolved Rabi splitting of 8 meV at resonance, an inhomogeneously broadened exciton transition of 4-5-meV width, and an 0.7-meV-wide Fabry-Pérot mode. The time-resolved transmission exhibits deep beatings and a subpicosecond exponential decay: a behavior similar to that foreseen in the strong-coupling regime and in the absence of electronic disorder. Conversely, the four-wave mixing response appears weakly influenced by the cavity and not much different from what is expected for bare excitons. A photon echo, dephasing times as long as 50 ps, and only weak Rabi oscillations are observed. The experimentally observed features can be explained by a model based on the numerical solutions of the Maxwell-Bloch equations. This model confirms the dramatic influence structural disorder in the quantum wells has on the coherent nonlinear exciton-photon dynamics.
Non-linear coupling of polariton and dark exciton states in semiconductor microcavities
Solid State Communications, 2005
We report a new mechanism of non-linear coupling of optically active and dark crystal states. We observe experimentally pronounced beats of the intensity of photoluminescence from a bottleneck region of the exciton-polariton band in a microcavity in the strong coupling regime and at strong pumping. These beats are extremely sensitive to the pumping intensity and vanish for weak pumping. We show theoretically that coherent polariton-polariton scattering which leads to the mixing between bright and dark exciton states can be responsible for this effect.
Physical Review B, 1999
A comprehensive theoretical and experimental study of linear exciton-light coupling in single and coupled semiconductor microcavities is presented: emphasis is given to angular dispersion and polarization effects in the strong-coupling regime. The phase delay in the dielectric mirrors carries a nontrivial angle and polarization dependence. The polarization splitting of cavity modes increases with internal angle as sin 2 eff . Comparison with experimental results on a GaAs-based cavity with In 0.13 Ga 0.87 As QW's shows that a quantitative understanding of polariton dispersion and polarization splitting has been achieved. Coupling of two identical cavities through a central dielectric mirror induces an optical splitting between symmetric and antisymmetric modes. When QW excitons are embedded in both cavities at antinode positions, the system behaves as four coupled oscillators, leading to a splitting of otherwise degenerate exciton states and to separate anticrossing of symmetric and antisymmetric modes. These features are confirmed by experimental results on coupled GaAs cavities with In 0.06 Ga 0.94 As QW's. Finally, the polarization splitting in a coupled cavity is analyzed in detail and is in good agreement with the experimental findings. ͓S0163-1829͑99͒03407-4͔ PRB 59 5083 EXCITON-LIGHT COUPLING IN SINGLE AND . . .
Theory of transient optical nonlinearities in semiconductor microcavities
2003
We present a theory of ultrafast time-resolved nonlinear spectroscopy in semiconductor microcavities including the influence of many-body and correlation effects beyond mean-field calculations. The theory, in close agreement with a number of experimental results, shows that semiconductor microcavities provide a unique tool for measuring the spectrum of four-particle correlations. We apply the theory to analyze the polariton parametric amplification in semiconductor microcavities. The obtained results demonstrate that excitonexciton collisions can be controlled and engineered to produce almost decoherence-free collisions for the realization of completely optical microscopic devices.
Intrinsic non-linearities in exciton-cavity-coupled systems
1999
We investigate the mechanisms leading to the optical non-linearities observed on a strongly excited semiconductor microcavity containing quantum wells. This study of a coupled exciton–cavity system is possible owing to the availability of a sample of exceptionally high quality, permitting to exclude effects of disorder and inhomogeneous broadening. Sub-picosecond pump and probe experiments are performed, in the regime of an incoherent exciton gas of high density.
Nonlinear Emission of Semiconductor Microcavities in the Strong Coupling Regime
Physical Review Letters, 2000
We report on the nonlinear laserlike emission from semiconductor microcavities in the strong coupling regime. Under resonant continuous wave excitation we observe a highly emissive state. The energy, dispersion, and spatial extent of this state is measured and is found to be dispersionless and spatially localized. This state coexists with luminescence that follows the usual cavity-polariton dispersion. It is attributed to the amplification of luminescence by a parametric gain due to cavity-polariton scattering. Despite the resonant excitation at 1.6 K, we observe no sign of Bose-Einstein condensation nor Boser action.
Off-branch polaritons and multiple scattering in semiconductor microcavities
2001
Exciton polaritons are the normal modes of the strong light-matter coupling in semiconductor microcavities. 1 Such half-light half-matter quasiparticles have sharply distorted energy dispersions and a pronounced nonlinear behavior, inherited from the cavity photon and quantum well exciton components, respectively. After the first nonlinear emission studies under nonresonant pumping, 2, 3 a significant acceleration of research has been devoted to the regime of resonant excitation.
Physical Review B, 1998
The narrowing of the exciton features in the optical spectra of quantum microcavities usually referred to as a motional narrowing is described within a simple semiclassical approach taking into account the exciton inhomogeneous broadening and assuming wave-vector conservation in the plane of the cavity. Good agreement with existing experimental data is achieved. The narrowing of exciton-photon modes in calculated spectra, however, cannot be called ''motional'' since no in-plane motion or quantization of excitons was assumed in the model. ͓S0163-1829͑98͒04704-3͔ *
Magnetic-field modulated exciton-exciton interaction in semiconductor microcavities
Journal of Applied Physics, 2010
We study the quantum-well magnetoexcitons by the variational method in the strong coupling regime of excitons with microcavity photons. In such strong coupling regime, we find that the coupling between the exciton internal state and center of mass motion can be neglected. Through the calculations, we find that the magnetic field can reduce the exciton exchange interaction to 30% as L w = 30 nm with L w being the quantum well width. This is in contrast to the magnetic-field enhancement in the exciton Rabi splitting. In this work, we obtain that a magnetic field can enhance the exciton Rabi splitting up to 1.6 times in the case of L w = 30 nm. They both originate from the local enhancement in the exciton internal state due to the magnetic field. In addition, we analyze the behavior of the magnetic response of the exciton energy, Rabi splitting, and exchange interaction in manipulating the polariton parametric scattering, and widening the microcavity applications.