Grating-coupled external-cavity short-wavelength (λ ≈ 3.9 μm) InGaAs/InAlAs/AlAs quantum-cascade lasers

In this work, the tunability properties of short-wavelength (λ ~ 3.9 μm) quantum-cascade lasers (QCLs) were studied, which is a first in the world at such short wavelengths. The experimental setup of an external cavity (EC) QCL was arranged in a Littrow configuration. A tuning range over 75 cm^?1 has been achieved by using an uncoated 23 μm stripe-width QCL at room temperature. A single-mode operation could be obtained at 2527 and 2544 cm^?1 at different grating angles by using an anti-reflection (AR) coated 23 μm ridge. A 5 μm stripe-width QCL without an AR coating could be tuned over 160 cm^?1.     

Interplay between phase formation mechanisms and magnetism in the Sr2FeMoO6–δ metal‐oxide compound

Double perovskites with the structural formula A₂BB′O_6±δ, especially the strontium ferromolybdate Sr₂FeMoO_6–δ, have attracted a lot of attention due to their unique magnetic and electrical properties and a possible application in spintronic devices. However, a strict correlation between the functional characteristics of Sr₂FeMoO_6–δ and its synthesis technology has been lacking up to date. Thus, we have studied in the present work the crystallization kinetics of Sr₂FeMoO_6–δ using reagents with different pre‐history as well as the structural and magnetic properties of the obtained compounds. Differences in the crystallization kinetics as well as higher magnetic inhomogeneity of Sr₂FeMoO_6–δ synthesised from a mixture of MoO₃, Fe₂O₃, SrCO₃ in comparison with the compound synthesised from the SrFeO_2.5 and SrMoO_4–y precursors have been found and interpreted. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)