Characterization of InGaAs and InGaAsN semiconductor saturable absorber mirrors for high-power mode-locked thin-disk lasers

We report a comparative study of carrier dynamics in semiconductor saturable absorber mirrors (SESAMs) containing InGaAs quantum wells and InGaAsN quantum wells (QWs). The static and dynamic reflectivity spectra were measured with a Fourier-transform-infrared-spectrometer and a pump-probe setup, respectively. The influence of rapid thermal annealing (RTA) on carrier dynamics was studied. Due to the reduction of defect states by RTA we observed an increase of the static reflectivity and an increase of the electron–hole recombination time.     

Parametric shape optimization of biaxial tensile specimen

Common cruciform specimen for biaxial tensile testing of sheet moulding compound, take damage and finally fail in uniaxially loaded areas. When using these specimen, an observation of damage initialization and failure in biaxially loaded areas is, therefore, not possible. In this paper, a parametric shape optimization is described to find a more suitable specimen shape. The parametrization of the specimen is presented. Objective functions are introduced to measure the appropriateness of specimen. A weighted summation transfers the constraint multiobjective optimization problem into a constraint scalar-valued problem. Findings of experiments suggest that a specimen shape with straight, non-tapering arms and slits along the arms is reasonable. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A new type of visco-plastic flow curve observed in certain concentrated diblock copolymer solutions

A diblock copolymer of styrene and isoprene (hydrogenated) is dissolved in C₁₁/C₁₂ n-paraffins and o-xylene (or cyclohexane) mixtures. An unusual type of flow curve is obtained in certain ranges of composition and under certain conditions of preparation. With increasing shear rates, the flow curve is first of the Bingham type, followed by a sudden shear thickening at almost discrete rate of shear and then by a second branch of almost linear increase. Time independent and reproducible behaviour can be achieved. A linear model is proposed and the possible molecular arrangement that corresponds to this model is discussed.Partly presented at the Annual Meeting of the Deutsche Rheologische Gesellschaft, May 13–15, 1985 in Berlin, FRG