Semiclassical theory of excitonic polaritons in a planar semiconductor microcavity (original) (raw)

Exciton–polaritons of a 2D semiconductor layer in a cylindrical microcavity

Journal of Applied Physics, 2020

We describe exciton-polariton modes formed by the interaction between excitons in a 2D layer of a transition metal dichalcogenide embedded in a cylindrical microcavity and the microcavity photons. For this, an expression for the excitonic susceptibility of a semiconductor disk placed in the symmetry plane perpendicular to the axis of the microcavity is derived. Semiclassical theory provides dispersion relations for the polariton modes, while the quantum-mechanical treatment of a simplified model yields the Hopfield coefficients, measuring the degree of exciton-photon mixing in the coupled modes. The density of states (DOS) and its projection onto the photonic and the excitonic subspaces are calculated taking monolayer MoS2 embedded in a Si3N4 cylinder as an example. The calculated results demonstrate a strong enhancement, for certain frequencies, of the total and local DOS (Purcell effect) caused by the presence of the 2D layer.

Dispersion of bulk exciton polaritons in a semiconductor microcavity

Physical Review B, 1996

Dispersion of two-dimensional ͑2D͒ exciton polaritons in a semiconductor microcavity containing bulk excitons in a central layer has been considered using the transfer-matrix technique and Pekar's additional boundary conditions. Solving dispersion equations for TE and TM polarized light modes we have obtained angle-dependent complex self-energies of eigenpolariton states, which have been compared with frequencies of resonant features in the calculated spectra. In TM polarization a pronounced spectral feature associated with the longitudinal polariton mode has been found in the vicinity of the lowest transverse polariton state, so that the 2D-polariton dispersion has a form of double anticrossing in this region. In the strong-coupling regime, the polariton splitting ͑Rabi splitting͒ decreases with an increasing index of the confined polariton state. Splittings between spectral dips exceed strongly Rabi splittings for higher exciton states. ͓S0163-1829͑96͒02343-0͔

Condensation of Semiconductor Microcavity Exciton Polaritons

Science, 2002

A phase transition from a classical thermal mixed state to a quantum-mechanical pure state of exciton polaritons is observed in a GaAs multiple quantum-well microcavity from the decrease of the second-order coherence function. Supporting evidence is obtained from the observation of a nonlinear threshold behavior in the pump-intensity dependence of the emission, a polariton-like dispersion relation above threshold, and a decrease of the relaxation time into the lower polariton state. The condensation of microcavity exciton polaritons is confirmed.

Crossover from exciton to biexciton polaritons in semiconductor microcavities

2000

Pump-probe measurements in a microcavity containing a quantum well show that a population of circularly polarized (s1) excitons can completely inhibit the transition to s2 one-exciton states by transferring the oscillator strength to the biexcitonic resonance. With increasing pump intensity the linear exciton-polariton doublet evolves into a triplet polariton structure and finally into a shifted biexcitonpolariton doublet.

Exciton polaritons in single and coupled microcavities

Journal of Luminescence, 2000

Recent work on strong coupling exciton}polariton phenomena in single and coupled microcavities is presented. We describe experiments for single cavities where the strong coupling nature of the excitations manifests itself. It is also shown that coupled cavities enable optically induced coupling between macroscopically separated exciton states to be achieved, and polaritons with strongly anisotropic properties to be realised. Results for both inorganic and organic microcavities are presented.

Theory of polariton photoluminescence in arbitrary semiconductor microcavity structures

Physical Review B, 1996

A quantum theory of quantum well polaritons in semiconductor microcavities is developed. The model takes into account the coupling between the exciton level and the structured continuum of electromagnetic modes relative to the particular geometry of the microcavity. A general equation for the polariton dispersion is obtained as a function of the cavity and exciton parameters. The equation is valid in both weak and strong coupling regimes and reproduces the existing measurements of microcavity polariton dispersion. A model for the polariton luminescence is then derived from the theory. It is possible to define a polariton decay rate only when the resonances in the polariton density of states can be considered as quasimodes. The two limiting cases of very weak and very strong coupling regimes are consequently identified. In these cases the polariton radiative probabilities are derived for light emitted on the left and right sides of the microcavity separately. The influence of the microcavity structure on the polariton dispersion and radiative rates is discussed and in particular the role of the microcavity leaky modes is described in detail. A discussion of the luminescence mechanism in the intermediate coupling case is also presented.

Polariton quantum boxes in semiconductor microcavities

Applied Physics Letters, 2006

We report on the realization of polariton quantum boxes in a semiconductor microcavity under strong coupling regime. The quantum boxes consist of mesas, etched on the top of the spacer of a microcavity, that confine the cavity photon. For mesas with sizes of the order of a few microns in width and nm in depth, we observe quantization of the polariton modes in several states, caused by the lateral confinement. We evidence the strong exciton-photon coupling regime through a typical anticrossing curve for each quantized level. Moreover the growth technique permits to obtain highquality samples, and opens the way for the conception of new optoelectronic devices.

Magnetic field tuning of exciton-polaritons in a semiconductor microcavity

Physical Review B, 2015

We detail the influence of a magnetic field on exciton-polaritons inside a semiconductor microcavity. Magnetic field can be used as a tuning parameter for exciton and photon resonances. We discuss the change of the exciton energy, the oscillator strength and redistribution of the polariton density along the dispersion curves due to the magnetically-induced detuning. We have observed that field-induced shrinkage of the exciton wave function has a direct influence not only on the exciton oscillator strength, which is observed to increase with the magnetic field, but also on the polariton linewidth. We discuss the effect of the Zeeman splitting on polaritons which magnitude changes with the exciton Hopfield coefficient and can be modelled by independent coupling of the two spin components of excitons with cavity photons.

GaAs microcavity exciton-polaritons in a trap

physica status solidi (b), 2008

We present a simple method to create an in-plane lateral potential in a semiconductor microcavity using a metal thin-film. Two types of potential are produced: a circular aperture and a onedimensional (1D) periodic grating pattern. The amplitude of the potential induced by a 24 nm-6 nm Au/Ti film is on the order of a few hundreds of µeV measured at 6 ~ 8 K. Since the metal layer makes the electromagnetic fields to be close to zero at the metal-semiconductor interface, the photon mode is confined more inside of the cavity. As a consequence, the effective cavity length is reduced under the metal film, and the corresponding cavity resonance is blue-shifted. Our experimental results are in a good agreement with theoretical estimates. In addition, by applying a DC electric voltage to the metal film, we are able to modify the quantum well exciton mode due to the quantum confined Stark effect, inducing a ~ 1 meV potential at ~ 20 kV/cm. Our method produces a controllable in-plane spatial trap potential for lower exciton-polaritons (LPs), which can be a building block towards 1D arrays and 2D lattices of LP condensates.