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Systematic excitation power and temperature-dependent measurements on the emission lines of single self-assembled InP/(Al0.20Ga0.80)0.51In0.49P quantum dots embedded in micropillars have been performed. The quantum dots were excited optically via a pulsed laser and their luminescence was collected using a micro-photoluminescence setup. The exciton and biexciton intensity, linewidth, and spectral position was investigated in a temperature range from 4 K up to 130 K. Single-photon emission from the quantum dots is presented up to a temperature of 100 K, confirmed by photon-statistics measurements. [ABSTRACT FROM AUTHOR]

Single lateral InGaAs quantum dot molecules have been embedded in a planar microcavity in order to increase the luminescence extraction efficiency. Using a combination of metal-organic vapor phase and molecular beam epitaxy samples could be produced that exhibit a 30 times enhanced single-photon emission rate. We also show that the single-photon emission is fully switchable between two different molecular excitonic recombination energies by applying a lateral electric field. Furthermore, the presence of a polarization fine structure splitting of the molecular neutral excitonic states is reported which leads to two polarization split classically correlated biexciton-exciton cascades. The fine structure splitting is found to be on the order of 10 μeV. [ABSTRACT FROM AUTHOR]

Emission from a resonantly excited quantum emitter is a fascinating research topic within the field of quantum optics and is a useful source for different types of quantum light fields. The resonance spectrum consists of a single spectral line that develops into a triplet above saturation of the quantum emitter. The three closely spaced photon channels from the resonance fluorescence have different photon statistical signatures. We present a detailed photon statistics analysis of the resonance fluorescence emission triplet from a solid-state-based artificial atom, that is, a semiconductor quantum dot. The photon correlation measurements demonstrate both 'single' and 'cascaded' photon emission from the Mollow triplet sidebands. The bright and narrow sideband emission (5.9 × 106 photons per second into the first lens) can be conveniently frequency-tuned by laser detuning over 15 times its linewidth (?v ? 1.0 GHz). These unique properties make the Mollow triplet sideband emission a valuable light source for quantum light spectroscopy and quantum information applications, for example. [ABSTRACT FROM AUTHOR]

We present a vertical external cavity surface-emitting laser system based on a multi-quantum-well structure with 20 compressively strained GaInP quantum wells for an operation wavelength of around 665 nm with a monolithic integrated distributed Bragg reflector. With the help of an intra-cavity diamond heatspreader the laser operates in continuous-wave mode. Operation with a TEM Gaussian beam profile and a beam propagation factor of M≤1.05 is shown as well as a high resolution spectrum of the laser line, which shows the etalon effect of the diamond. The laser can be operated at a maximum output power exceeding 1.2 W with a slope efficiency of η=18%. At maximum output power the wavelength of the laser resonance is at 670 nm, which is shortest reported until now at powers exceeding 1 W. By rotating a birefringent filter in an extended folded cavity arrangement a wavelength tuning of 21 nm was attained. [ABSTRACT FROM AUTHOR]

In Germany and France, different approaches to oral health promotion have been chosen. Objectives: It was the aim of the present study to assess whether different preventive measures were positively or negatively associated with caries experience in 12-year-old children in Heidelberg, Germany, and in Montpellier, France. METHODS: In the school year 1998/99, 12-year-old children were examined in Heidelberg (n=864) and in Montpellier (n =828). D3+4MFT, D3+4MFS (D3+4=dentinal caries), prevalence of fissure sealants and use of fluorides were recorded. RESULTS: The mean D3+4MFT scores of the pupils in Heidelberg and Montpellier were 1.56 and 1.42, the proportion of caries-free children being 43.5% and 46.9%, respectively. In 63.2% of the children in Heidelberg and in 6.8% of the children in Montpellier, at least one fissure sealed tooth was found. Fluoridated salt was used by 38.8% of families of the 12-year-olds from Heidelberg and the corresponding value was 73.3% in Montpellier. Topical fluorides were applied by 39.9% of the children in Heidelberg, but only by 5.4% of pupils in Montpellier. Multiple regression analysis revealed that, in Heidelberg, fissure sealants and the combination of topical fluorides and fluoridated salt were negatively associated with the D3+4MFT values, while in Montpellier the frequency of dental visits was positively associated with the D3+4MFT scores. CONCLUSION: A further decrease in the caries experience of 12-year-old children may well be obtainable by enlarging the share of marketed fluoridated salt in Heidelberg, by increasing the application of fissure sealants in Montpellier, and by extending the use of topical fluorides in both cities. [ABSTRACT FROM AUTHOR]

In Germany and France, different approaches to oral health promotion have been chosen, Objectives: It was the aim, of the present study to assess whether different preventive measures were positively or negatively associated with caries experience in 12-year-old children in Heidelberg, Germany, and in Montpellier, France, Methods: In the school year 1998/99, 12-year-old children were examined in Heidelberg (n=864) and in Montpellier (n =828), D[SUB3+4]MFT, D[SUB3+4]MFS (D[SUB3+4]= dentinal caries), prevalence of fissure sealants and use of fluorides were recorded. Results: The mean D[SUB3+4]MFT scores of the pupils in Heidelberg and Montpellier were 1.56 and 1.42, the proportion of caries free Children being 43.5% and 46.9%, respectively. In 63.2% of the children in Heidelberg and in 6.8% of the children Montpellier, at least one fissure sealed tooth was found. Fluoridated salt was used by 38.8% of families of the 12-year-olds from Heidelberg and the corresponding value was 73.3% in Montepellier, Topical fluorides were applied by 39.9% of the children in Heidelberg, but only by 5.4% of pupils in Montpellier. Multiple regression analysis revealed that, in Heidelberg, fissure sealants and the combination of topical fluorides and fluoridated salt were negatively associated with the D[SUB3+4]MFT values, while in Montpellier the frequency of dental visits was positively associated with the D[SUB3+4]MFT scores. Conclusion: A further decrease in the caries experience of 12-year-old children may well be obtainable by enlarging the share of marketed fluoridated salt in Heidelberg, by increasing the application of fissure sealants in Montpellier, and by extending the use of topical fluorides in both cities. [ABSTRACT FROM AUTHOR]

We demonstrate an optically pumped vertical external-cavity surface-emitting laser in a compact v-shaped cavity configuration for frequency doubling to the ultraviolet (UV) spectral range at ∼330 nm. The fundamental red laser emission is realized with a metal-organic vapor-phase epitaxy grown (GaxIn1-x)0.5P0.5/[(AlxGa1-x)yIn1-y]0.5P0.5 multi-quantum-well structure. Second harmonic generation is accomplished by using a beta barium borate non-linear crystal to generate maximum UV output powers exceeding 100 mW. By using a birefringent filter, we are able to tune the fundamental laser resonance to realize a maximum tuning range of 7.5 nm of the second harmonic. [ABSTRACT FROM AUTHOR]

Pulsed electrical excitation was used to excite single InP/Ga0.51In0.49P quantum dots and obtain triggered single-photon emission in the red spectral range at an excitation repetition rate of up to 200 MHz. Increased repetition rates are prevented by the finite decay-time, and autocorrelation measurements look similar to what is expected for dc injection above 1 GHz. Finally, it is shown that negative voltage pulses can increase the decay-rate considerably such that 1 GHz excitation rates should be possible. [ABSTRACT FROM AUTHOR]

Small-signal properties of 650-nm vertical-cavity surface-emitting lasers (VCSELs) with different oxide aperture sizes were measured. A small diameter VCSEL of 3.5 mum has a maximum resonance frequency of 5.7 GHz. The photon density determines the maximum resonance frequency. Modeling also indicates higher photon densities in the small VCSEL due to better thermal behavior [ABSTRACT FROM PUBLISHER]

Pulsed lasing operation of a 670 nm AlGaInP-based oxide-confined vertical-cavity surface-emitting laser (VCSEL) at high temperatures is demonstrated. At +120°C heatsink temperature output power exceeded 0.5 mW and at +160°C 25 µW output power was achieved. [ABSTRACT FROM AUTHOR]

The heteroepitaxy of III–V semiconductors on silicon is a promising approach for making silicon a photonic platform. Mismatches in material properties, however, present a major challenge, leading to high defect densities in the epitaxial layers and adversely affecting radiative recombination processes. However, nanostructures, such as quantum dots, have been found to grow defect-free even in a suboptimal environment. Here we present the first realization of indium phosphide quantum dots on exactly oriented Si(001), grown by metal–organic vapour-phase epitaxy. We report electrically driven single-photon emission in the red spectral region, meeting the wavelength range of silicon avalanche photodiodes’ highest detection efficiency. [ABSTRACT FROM AUTHOR]