Stability of ZnSe-Passivated Laser Facets Cleaved in Air and in Ultra-High Vacuum

Catastrophic optical mirror damage (COMD) is one of the main failure mechanisms limiting the reliability of GaAs based laser diodes. Here, we compare the facet stability of ZnSe-passivated ridge-waveguide lasers (RWLs) that are cleaved in air and subsequently cleaned using atomic hydrogen with RWLs that are cleaved in ultra-high vacuum. RWLs cleaved in ultra-high vacuum show a superior performance and reach power densities up to 58 MW/cm 2 under extended continuous wave operation at 1064 nm. This is attributed to the reduction of defects at the interface between ZnSe and the cleaved facet as evidenced by transmission electron microscopy and X-ray diffraction

783 nm wavelength stabilized DBR tapered diode lasers with a 7 W output power

Wavelength stabilized distributed Bragg reflector (DBR) tapered diode lasers at 783 nm will be presented. The devices are based on GaAsP single quantum wells embedded in a large optical cavity leading to a vertical far field angle of about 29◦ (full width at half maximum). The 3-inch (7.62 cm) wafers are grown using metalorganic vapor phase epitaxy. In a full wafer process, 4 mm long DBR tapered lasers are manufactured. The devices consist of a 500 µm long 10th order surface DBR grating that acts as rear side mirror. After that, a 1 mm long ridge waveguide section is realized for lateral confinement, which is connected to a 2.5 mm long flared section having a full taper angle of 6◦. At an injection current of 8 A, a maximum output power of about 7 W is measured. At output powers up to 6 W, the measured emission width limited by the resolution of the spectrometer is smaller than 19 pm. Measured at 1/e2 level at this output power, the lateral beam waist width is 11.5 µm, the lateral far field angle 12.5◦, and the lateral beam parameter M2 2.5. The respective parameters measured using the second moments are 31 µm, 15.2◦, and 8.3. 70% of the emitted power is originated from the central lobe. © 2021 Optical Society of Americ

Individual Facial Coloration in Male Eulemur fulvus rufus: A Condition-dependent Ornament?

Researchers studying individual variation in conspicuous skin coloration in primates have suggested that color indicates male quality. Although primate fur color can also be flamboyant, the potential condition dependence and thus signaling function of fur remains poorly studied. We studied sources of variation in sexually dichromatic facial hair coloration in red-fronted lemurs (Eulemur fulvus rufus). We collected data on 13 adult males in Kirindy Forest, Madagascar, during two study periods in 2006 and 2007, to determine whether variation in facial hair coloration correlates with male age, rank, androgen status, and reproductive success. We quantified facial hair coloration via standardized digital photographs of each male, assessed androgen status using fecal hormone measurements, and obtained data on reproductive success through genetic paternity analyses. Male facial hair coloration showed high individual variation, and baseline coloration was related to individual androgen status but not to any other parameter tested. Color did not reflect rapid androgen changes during the mating season. However, pronounced long-term changes in androgen levels between years were accompanied by changes in facial hair coloration. Our data suggest that facial hair coloration in red-fronted lemur males is under proximate control of androgens and may provide some information about male quality, but it does not correlate with dominance rank or male reproductive success

A combined in situ monitoring approach for half cell state of charge and state of health of vanadium redox flow batteries

Bundesministerium für Wirtschaft und Energi

Lena und Papas Auslandseinsatz

Das ist die Geschichte von Lena und ihrem Bruder Max. Ihr Papa ist Soldat und arbeitet in einer Kaserne. Manchmal muss er aber auch länger in einem anderen Land arbeiten.Er nennt das dann "in den Einsatz gehen" oder "auf Manöver". Das ist keine leichte Zeit für Lena, Max und ihre Mama. Denn ihr Papa wird eine lange Zeit nicht bei ihnen daheim sein können. So wie Lena und Max geht es vielen Kindern in Soldatenfamilien. Bei den einen ist es die Mama, die Soldatin ist. Bei anderen ist es der Papa, der Soldat ist. Und manchmal sind sogar beide - Mama und Papa - Soldaten. In dem Buch erzählt Lena, wie sie und ihr Bruder Max die Zeit des Einsatzes zusammen mit Mama erleben: Was bis Papas Abreise und nach seinem Abschied zu Hause, im Kindergarten oder in der Schule passieren kann. Bis es dann endlich Zeit ist, ihn wieder vom Flughafen abzuholen. Und die zwei erzählen, wie sich das alles für Lena und Max anfühlt