S. Laurent

Influence of an in-plane electric field on exciton fine structure in InAs-GaAs self-assembled quantum dots

The influence of an in-plane electric field on the optical properties of single quantum dots is investigated. On a sample containing a plane of InAs∕GaAs dots, micrometer-size electro-optical structures were produced in order to apply an external electric field in the dot plane. A large decrease of the anisotropic exchange splitting, correlated with the in-plane Stark shift, is observed.

Indistinguishable single photons from a single-quantum dot in a two-dimensional photonic crystal cavity

We report on the spontaneous emission of a single-quantum dot embedded in a two-dimensional photonic crystal cavity. The resonant coupling between the dot and the strongly localized optical mode significantly shortens the spontaneous emission lifetime, so that the coherence time of the emitted photons is dominated by radiative effects: The emitted photons are indistinguishable, with a mean wave-packet overlap as high as 72%.

Submicron-diameter semiconductor pillar microcavities with very high quality factors

Pillar microcavities are subject to two common fabrication artifacts: Bragg mirror corrugation and oxide deposit cladding. In this letter the authors investigate the impact of these features on the quality factor. A quasiperiodic variation of the quality factor as a function of the pillar diameter is experimentally observed and well described by theory. Moreover, observation of quality factors in excess of 1500, close to the theoretical limit, is reported for 600-nm-diameter GaAs micropillars bounded by AlGaAs∕GaAs Bragg mirrors.

Fast radiative quantum dots: From single to multiple photon emission

Photon correlation measurements are performed on single GaAs quantum dots with various excitonic radiative lifetimes. A continuous increase of the probability that the quantum dot emits more than one photon per excitation pulse is observed when decreasing the exciton radiative lifetime. The authors show that this increase is due to recapture processes into the quantum dot. A model for the second-order autocorrelation function including relaxation processes is developed and gives good description of the experimental observations.

Reactive-ion etching of high-Q and submicron-diameter GaAs∕AlAs micropillar cavities

We present a fabrication process allowing the realization of high-Q and small-diameter micropillar cavities. The fabrication involves molecular beam epitaxy, electron-beam lithography, and reactive ion etching (RIE). The introduction of O2 to the SiCl4 RIE plasma and the dynamic adjustment of its flow rate enable the control of the etched profile throughout the process, through the deposition of silicon oxide on the vertical etched surfaces. The resulting cavities have very smooth, straight, and vertical sidewalls and remain optically and mechanically stable for long periods of time. The optical modes sustained by these cavities exhibit record quality factors in excess of 1200 for pillar diameters close to 400nm, which underscores the quality of our process.

Tuning InAs/InP(001) quantum dot emission from 1.55 to 2 μm by varying cap-layer growth rate in metalorganic vapor phase epitaxy

This contribution shows that the control of the cap-layer growth rate of InAs/InP(001) quantum dots grown by metalorganic vapor phase epitaxy allows to control their emission wavelength. By varying the cap-layer growth rate over a factor 12, the emission is tuned between 1.55 and 2 mum.

InAsP/InP(001) quantum dots emitting at 1.55 μm grown by metalorganic vapor phase epitaxy

This contribution reports the growth of InAsP quantum dots on InP(001) using metalorganic vapor phase epitaxy. We show that the control of the voluntary phosphorus incorporation into the quantum dots allows both to tune their emission to 1.55 mum and to improve their optical properties.

Selective monoalkylation of the fulvene-type enolates of 4-alkylidene- cyclopentenones

4-Alkylidenecyclopentenones were shown to be prone to polyalkylation because of their very easy enolization. They were selectively monoalkylated through the organozinc aided alkylation of their new fulvene-type enolates.

Study of the Quality Factor of Micropillar Cavity

We study micropillar cavity and we show that their Q-factor can exhibit an oscillatory behavior. We provide an analysis of the physical mechanisms at the origin of these oscillations and a comparison with experimental measurements.

Indistinguishable single photons from a single quantum dot

This work reports on development of a source of indistinguishable photons based on a single quantum dot emitter coupled to a pillar microcavity.