Thermal resistance of ridge-waveguide laser diodes based on GaAs,GaSb or InP

The effects of different substrates (GaAs, GaSb and InP) on the thermal properties of laser diodes with a ridge-waveguide structure are presented. Laser diodes with the same basic geometry exhibit different thermal resistances. The reason is therefore the difference in thermal conductivity of the substrates and the active layer compounds. This leads to different temperature distributions in the structures. The theoretical results were supported by experimental data.

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Zusammenfassung Es wurde der Einfluß verschiedener Substrate (GaAs, GaSb und InP) auf die thermischen Eigenschaften von Laserdioden mit gefurchter Hohlleiterstruktur untersucht. Laserdioden mit dem gleichen geometrischen Grundaufbau zeigen verschiedene Wärmewiderstände. Die Ursache ist folglich der Unterschied in der Wärmeleitfähigkeit der Substrate und der Verbindungen der aktiven Schicht. Dies führt zu einer unterschiedlichen Temperaturverteilung in der Strukturen. Theoretische Ergebnisse werden durch experimentelle Daten bekräftigt.

     

Stabilized finite element method for flows with multiple reference frames

We present a space‐time finite element method capable of dealing with flows in multiple co‐rotating reference frames. Since equal order interpolation is used for all degrees of freedom, Galerkin/least‐squares stabilization is applied. We give a detailed derivation of the equations involved, introduce the variational form, present the stabilization parameters, and also discuss implementation issues. Numerical examples in 2D and 3D show generality and efficiency of the method, if steady‐state behavior of rotating components is sufficient for the CFD analysis. Copyright © 2015 John Wiley & Sons, Ltd.     

Thermal resistivity of quaternary solid solutions InGaSbAs and GaAlSbAs lattice-matched to GaSb

Measurement of the thermal resistivity of the materials InGaSbAs and GaAlSbAs is reported. These materials have thermal resistivities of three to four times that of the GaSb substrate to which they were lattice matched. This makes them particularly suitable for use as the active medium in semiconductor light sources.<>     

Synthesis of 2-hydroxyethylsulfonyl-methyl-substituted polystyrenes and their application in solid phase peptide synthesis

2-Hydroxyethylsulfonylmethyl-substituted polystyrenes are obtained from Merrifield's chloromethylated, cross-linked copolymer, by treatment with sodium 2-hydroxyethylmercaptide in liquid ammonia, followed by oxidation with m-chloroperbenzoic acid. Boc-amino acids can be esterified with the polymer, using dicyclohexylcarbodiimide in dichloromethane. Further condensations are possible via conventional procedures. Protected peptide derivatives, thus prepared, can be detached from the resin by brief treatment with a base. A high elimination rate was observed when the cleavage was performed with a 0.1 M solution of sodium hydroxide containing methanol and a limited amount of water. In the absence of methanol only trace amounts of the product were liberated.