Tuning nonlinear susceptibility in strained AlGaAs/InGaAs quantum cascade lasers

This paper explores enhancement of nonlinear susceptibility in strained quantum cascade lasers (QCLs) that lead to unique intracavity characteristics that include frequency mixing producing both fundamental and higher order modes that propagate freely within a GaAs matrix. Doing so provides a QCL cavity design with emission near the 3.5 μm range, a region suitable for applications within the 3–5 μm atmospheric transmission window. In this study, a self-consistent Schrodinger–Poisson solver was employed to analyze the effects of strain within an AlGaAs/InGaAs active region between AlGaAs/GaAs injectors on a [1 1 1] GaAs matrix for the purpose of enhancing nonlinear susceptibility. Strain relief available through the use of [1 1 1] GaAs allows increased indium composition in the active region and results in observation of second-harmonics below the 5 μm range with tunable optical dipole moments and oscillator strengths. Results demonstrate the feasibility of strained AlGaAs/InGaAs devices on GaAs for producing higher order harmonics that lay below the 4 μm spectral limit.     

Electrochemistry-guided isolation of antioxidant metabolites from Sargassum elegans

Electrochemical techniques offer a rapid and simple alternative method for the analysis of bioactive compounds with antioxidant properties in crude samples. In this study we use square wave and cyclic voltammetry methods to guide the isolation of antioxidant natural products from the marine brown alga, Sargassum elegans (Suhr). Four pure antioxidants were isolated and identified by standard spectroscopic techniques as sargaquinoic acid, sargahydroquinoic acid, sargaquinal and fucoxanthin.     

Sensitivity of Strained and Unstrained Structure Growth on GaAs (111)B

Compared with traditional (100) surfaces, the growth window for achieving high-quality photonic device structures on (111) GaAs by conventional molecular beam epitaxy (MBE) is very narrow. However, strained and unstrained structures produced on (111) substrates offer a new class of electronic and optoelectronic devices that benefit from the piezoelectric effect—a feature not accessible on symmetric (100) orientations—and additional material choices, such as InAs and InGaAs. In this work, we report on a series of investigations of strained and unstrained structures that include GaAs, AlGaAs/GaAs, and InAs/GaAs quantum layers deposited on epi-ready GaAs (111)B 2° → [2[`1][`1] 2\bar{1}\bar{1} ] Si-doped substrates by conventional MBE.     

Thermomagnetic Correlation in La0.85-xBixNa0.15MnO3 Soft Ferromagnet due to Nonmagnetic Bi3+ Substitution

Journal of Superconductivity and Novel Magnetism - We report the structural, magnetic, and magnetocaloric properties of Bismuth (Bi)-substituted manganite La0.85-xBixNa0.15MnO3 (x=0, 0.1, 0.2,...