Submonolayer quantum dots for high speed surface emitting lasers.

We report on progress in growth and applications of submonolayer (SML) quantum dots (QDs) in high-speed vertical-cavity surface-emitting lasers (VCSELs). SML deposition enables controlled formation of high density QD arrays with good size and shape uniformity. Further increase in excitonic absorption and gain is possible with vertical stacking of SML QDs using ultrathin spacer layers. Vertically correlated, tilted or anticorrelated arrangements of the SML islands are realized and allow QD strain and wavefunction engineering. Respectively, both TE and TM polarizations of the luminescence can be achieved in the edge-emission using the same constituting materials. SML QDs provide ultrahigh modal gain, reduced temperature depletion and gain saturation effects when used in active media in laser diodes. Temperature robustness up to 100 °C for 0.98 µm range vertical-cavity surface-emitting lasers (VCSELs) is realized in the continuous wave regime. An open eye 20 Gb/s operation with bit error rates better than 10-12has been achieved in a temperature range 25-85 °Cwithout current adjustment. Relaxation oscillations up to ∼30 GHz have been realized indicating feasibility of 40 Gb/s signal transmission.

Non-classical light emission from a single electrically driven quantum dot.

Easy to handle light sources with non-classical emission features are strongly demanded in the growing field of quantum communication. We report on single-photon emission from an electrically pumped quantum dot with unmatched spectral purity, making spatial or spectral filtering dispensable.

[Effect of age on the incidence of postoperative wound infections]. / Der Einfluss des Lebensalters auf die Häufigkeit postoperativer Wundinfektionen.

The incidence of postoperative wound infections was found to grow in dependence on age, because of higher incidence in advanced age of accompanying disorders. Follow-up checks were made on 661 patients without such accompanying disorders, and evidence was produced to the effect that physiological ageing alone had no impact on postoperative wound infection rates. Age-related physiological changes are discussed in some detail.

[Prognosis of wound healing]. / Beitrag zur Prognose der Wundheilung.

The knowledge of prognosis of wound healing ist important for the preparation of patients to the operation and for prophylaxis of wound infections. This study on 625 patients demonstrates a method for investigation an objective prognosis. The method allows the selection of patients with a high risk of wound infection.