ABSTRACT
The emission dynamics in GaAs/AlGaAs coupled ring-disk (CRD) quantum structures fabricated on silicon substrates is presented. The CRD structures are self-assembled via droplet epitaxy, a growth technique which, due to its low thermal budget, is compatible with the monolithic integration of III-V devices on Si based electronic circuits. Continuous wave, time resolved photoluminescence and theoretical calculations in the effective mass approximations are presented for the assessment of the electronic and carrier properties of the CRDs. The CRDs show a fast carrier dynamics which is expected to be suitable for ultrafast optical switching applications integrated on silicon.
ABSTRACT
A revisited realization of the Young's double slit experiment is introduced to directly probe the photonic mode symmetry by photoluminescence experiments. We experimentally measure the far field angular emission pattern of quantum dots embedded in photonic molecules. The experimental data well agree with predictions from Young's interference and numerical simulations. Moreover, the vectorial nature of photonic eigenmodes results in a rather complicated parity property for different polarizations, a feature which has no counterpart in quantum mechanics.
ABSTRACT
We realized ultra-narrow excitonic emission from single GaAs/AlGaAs quantum dots (QDs) grown by a refined droplet epitaxy technique. We found that uncapped quantum dots can be annealed at 400 degrees C without major changes in their morphology, thus enabling an AlGaAs capping layer to be grown at that temperature. Consequently, we demonstrate a fourfold reduction of the linewidth of the emission together with an increased recombination lifetime, compared to the conventional droplet epitaxial QDs. The averaged linewidth of neutral excitons measured by micro-photoluminescence on single quantum dots was around 35 microeV.
ABSTRACT
We have studied the photoluminescence properties of GaN quantum dots with submicrometre lateral resolution by means of near-field scanning optical microscopy. The instrument operated at room temperature and was implemented for near-ultra-violet spectroscopy in the illumination-mode configuration. The analysed sample consisted of several stacked planes of GaN/AlN quantum dots grown by molecular beam epitaxy on Si(111) substrate. The photoluminescence maps showed islands in the micrometre range emitting at different wavelengths, confirming the atomic force microscopy studies on the morphology of similar uncapped samples.
ABSTRACT
Propofol is a new anaesthetic agent commonly used because of its rapid pharmacokinetic. Lately, anecdotal reports suggest its utility in the treatment of convulsive status epilepticus. We describe four cases of convulsive status due to severe encephalopathy of various etiology. They were resistant to diazepam and other drugs and remitted only after treatment with propofol. The infusion, even protracted to 8 days, did not cause any toxic or proconvulsive side-effects. The very short duration of its central depressant action permitted monitoring of the underlying neurological status whenever needed.
Subject(s)
Propofol/therapeutic use , Status Epilepticus/drug therapy , Adult , Aged , Female , Humans , Male , Middle AgedABSTRACT
A cervical intramedullary spinal ependymal cyst in a 39-year-old man is reported. Diagnosis was made through magnetic resonance imaging. Total enucleation was possible. This is the sixth such reported case.
