Light In Microcavities Research Articles

Optical anisotropy and pinning of the linear polarization of light in semiconductor microcavities

We report strong experimental evidence of the optical anisotropy in a CdTe-based microcavity: the polarization of light is pinned to one of the crystallographic axes independently of the polarization of the excitation. The polarization degree depends strongly on the excitation power, reaching almost 100% in the stimulated regime. The relaxation time of the polarization is about 1 ns. We argue that all of this is an effect of a splitting of the polariton doublet at k = 0 . We consider different sources for the splitting and conclude that the most likely one is optical birefringence in the mirrors and/or the cavity.

Exciton–polaritons in organic microcavities

We review shortly the main peculiarities of the regime of strong coupling between light and electronic transitions in planar organic microcavities. We consider the excitation spectrum, new relaxation processes, and point out a suppression of bimolecular quenching of excitations, which is particularly important for non-linear processes in organic materials. This review is dedicated to the memory of Gerald Small.

Optical Spin Hall Effect

A remarkable analogy is established between the well-known spin Hall effect and the polarization dependence of Rayleigh scattering of light in microcavities. This dependence results from the strong spin effect in elastic scattering of exciton polaritons: if the initial polariton state has a zero spin and is characterized by some linear polarization, the scattered polaritons become strongly spin polarized. The polarization in the scattered state can be positive or negative dependent on the orientation of the linear polarization of the initial state and on the direction of scattering. Very surprisingly, spin polarizations of the polaritons scattered clockwise and anticlockwise have different signs. The optical spin Hall effect is possible due to strong longitudinal-transverse splitting and finite lifetime of exciton polaritons in microcavities.

Quantum beats between light and dark polariton states in semiconductor microcavities

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. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Nonlinear dissipation and the quantum noise of light in semiconductor microcavities

Our work presents a theoretical study on the behaviour of the noise spectra of the light reflected by a microcavity containing a semiconductor quantum well. In the case of very small nonlinear dissipation, we have obtained significant squeezing, even though we have assumed a small nonlinear excitonic interaction. We show that the nonlinear dissipation destroys the squeezing and decreases the photonic and excitonic densities in the microcavity.

Polarisation rotation in resonant emission of semiconductor microcavities

We present the semi-classical theory of the non-linear propagation of polarized light in semiconductor microcavities. This formalism explains the mysterious rotation of the polarization plane of light emitted by a microcavity in the regime of stimulated scattering observed recently. The model describes the stimulated four-wave mixing in microcavities. We show that the exciton spin-splitting induced by the polarized pumping is responsible for giant resonant Faraday rotation of the polarization plane of light emitted by the cavity.

Polariton laser and polariton superfluidity in microcavities

Excitons coupled to light in microcavities form exciton–polaritons (polaritons) having very light effective masses. These 2-dimensional quasiparticles exhibit local condensation or Kosterlitz–Thouless phase transition towards superfluidity, allowing for polariton lasing at temperatures that could be higher than 300 K. Polariton lasers are devices producing monochromatic and coherent light spontaneously emitted by Bose-condensed exciton–polaritons. They do not require inversion of population and, theoretically, have no threshold. We show great advantages of cavity polaritons with respect to excitons to achieve bosonic phase transition. We review experimental and theoretical activity that has been developed in this research field since the discovery of strong exciton-light coupling in microcavities 10 years ago. We present basic thermodynamic properties of polariton systems modeled as a weakly interacting Bose gas at equilibrium. We present an analysis of the relaxation kinetics of cavity polaritons in the framework of a semiclassical Boltzmann equation. The main obstacle that prevents polariton condensation is their finite lifetime: polaritons disappear before they have time to condense. We discuss the ways to improve their relaxation kinetics in real structures.

Electron Acceleration by Light in Semiconductor Microcavities

Electron Acceleration by Light in Semiconductor Microcavities

Electron Acceleration by Light in Semiconductor Microcavities

We theoretically consider effects linked to the electron–exciton-polariton scattering in semiconductor microcavities. The scattering matrix element is derived analytically in the Born approximation. The pump–probe optical experiment is simulated using rate equations. The stimulated electron–exciton-polariton scattering is shown to result in the creation of picosecond pulses of spin-polarized electrical current in the plane of a doped semiconductor microcavity.

Squeezed states and the quantum noise of light in semiconductor microcavities

A theoretical investigation of the quantum noise in the light reflected by a microcavity containing a semiconductor quantum well is presented. Squeezing is predicted when scattering processes have a low efficiency. Exciton-phonon scattering is shown to destroy the non-classical effects and to yield excess noise in the output field.

Faraday rotation of light in a microcavity

Faraday rotation of light in microcavities is studied theoretically. The reflection and transmission spectra are calculated. It is shown that in the region of the spectrum corresponding to a characteristic mode of the cavity the Faraday rotation is strongly intensified and the polarization of the light changes substantially.

Enhanced diffraction of light in GaAs microcavities

We theoretically analyze the diffraction of light by gratings that are photogenerated in Fabry–Perot microcavities. The coupled-wave theory of volume gratings is combined with appropriate boundary conditions to yield expressions for the diffraction efficiency. Multiple round trips within the cavity are seen to increase the effective grating thickness and therefore the efficiency. Numerical calculations specific to GaAs microcavities show that the diffraction efficiency can be enhanced by more than 2 orders of magnitude at the resonant wavelengths.