A. K. Nowak

Emission polarization control in semiconductor quantum dots coupled to a photonic crystal microcavity

We study the optical emission of single semiconductor quantum dots weakly coupled to a photonic-crystal micro-cavity. The linearly polarized emission of a selected quantum dot changes continuously its polarization angle, from nearly perpendicular to the cavity mode polarization at large detuning, to parallel at zero detuning, and reversing sign for negative detuning. The linear polarization rotation is qualitatively interpreted in terms of the detuning dependent mixing of the quantum dot and cavity states. The present result is relevant to achieve continuous control of the linear polarization in single photon emitters.

Single-photon emission by semiconductor quantum rings in a photonic crystal

Photon correlation measurements on single InAs/GaAs quantum rings embedded in a photonic crystal lattice demonstrate single-photon emission with g(2)(0) values of 0.4 and photon antibunching between the exciton and biexciton emissions. The measured photon antibunching times of the excitons are longer than that of the biexcitons, resulting in the time asymmetry of the exciton-biexciton photon cross-correlation. Phonon sidebands due to the piezoelectric coupling of excitons to acoustic phonons broaden the emission lines and shift them to lower energies at low excitation intensity.

Single photon emission and quantum ring-cavity coupling in InAs/GaAs quantum rings

Different InAs/GaAs quantum rings embedded in a photonic crystal microcavity are studied by quantum correlation measurements. Single photon emission, with g (2) (0) values around 0.3, is demonstrated for a quantum ring not coupled to the microcavity. Characteristic rise-times are found to be longer for excitons than for biexcitons, resulting in the time asymmetry of the exciton-biexciton cross-correlation. No antibunching is observed in another quantum ring weakly coupled to the microcavity.

Single photon emission dynamics of InP-InGaP quantum dots under p-shell excitation

Single photon emitters based on InP/GaInP quantum dots have been studied under p-shell excitation by time-resolved photoluminescence and photon correlation spectroscopy. By tuning the excitation energy in resonance with quantum dot excited states, we observe a marked decrease of the antibunching time as a result of the increased excitation rate for decreasing energy detuning. A similar behavior is observed by increasing the pump power. The spectral dependence of the antibunching rate follows the energy profile of the excited state, as measured by photoluminescence excitation.

Microcavity‐Mediated Coupling of Two Distant InAs/GaAs Quantum Dots

We demonstrate the effective coupling between two distant quantum dots embedded in a photonic crystal microcavity. Time‐resolved measurements reveal the simultaneous coupling of both quantum dots to the cavity mode by the Purcell effect. The cavity mediates an interaction between the quantum dots which is evidenced by the increase in the emission intensity of each dot upon the resonant excitation at the excited state of the other one. A linear polarization rotation is observed in one of the dots when the detuning from the cavity mode is varied, which is explained in terms of the hybridization of the quantum dot states and the cavity mode.

Dynamics of InP/(Ga,In)P quantum‐dot single‐photon emitters

The dynamics of single photon emitters based on InP/(Ga,In)P quantum dots (QDs) has been studied by time‐resolved photo luminescence (TRPL) and photon correlation spectroscopy (PCS) up to 50 K. The increase of temperature produces marked effects on the exciton photoluminescence (PL) decay time (τX) and on the anti‐bunching time (τR) in the second order photon correlation function. Both times are found to depend on the QD size. A competition of the thermally activated Dark‐to‐Bright (D→B) exciton transition and the thermal excitation of the carriers to‐ and from the QD give a good qualitative understanding of the observed results. Resonant excitation at the QD p‐states produces a marked decrease of τR together with the appearance of time bunching in a longer time scale.