Compact, Watt-class 785 nm dual-wavelength master oscillator power amplifiers

785 nm micro-integrated, dual-wavelength master oscillator power amplifiers with a footprint of 5 mm × 25 mm are presented. They are based on Y-branch distributed Bragg reflector ridge waveguide diode lasers and anti-reflection coated tapered amplifiers. In order to reduce the impact of potential optical feedback, devices with master oscillator front facet reflectivities of 5% and 30% as well as with an integrated miniaturized optical isolator have been realized. A comparison up to 1 W shows narrowband dual wavelength laser emission with a spectral distance of 0.6 nm (10 cm−1) and individual spectral widths <20 pm. As expected, a higher front facet reflectivity leads to a significant reduction of feedback related mode hops. Longitudinal modes corresponding to the master oscillator resonator length remain within spectral windows <0.15 nm (3 cm−1), suitable for applications such as Raman spectroscopy and especially shifted excitation Raman difference spectroscopy. Integrating a compact 30 dB optical isolator completely eliminates the observed optical feedback effects. Lateral beam propagation ratios of 1.2 (1/e2) enable easy beam shaping and fiber coupling. Outside of the experimental comparison, the developed MOPAs provide up to 2.7 W of optical output power available for applications

Spektroskopische Speziation und thermodynamische Charakterisierung der Komplexierung des Np(V)-Ions

The geochemistry of the actinides is of particular interest for the safety case of a nuclear waste repository. The present work focuses on the complexation of pentavalent actinides An(V) with different organic and inorganic ligands in aqueous solution at elevated temperatures. In the first part of the thesis the complexation of NpO2+ with different mono- and dicarboxylic ligands (formate, acetate, oxalate, malonate, succinate) and hydorxyl functionalized carboxylates (lactate, malate, tartrate) is studied. These ligands are either naturally occuring substances in the pore waters of clay rocks or serve as model ligands for macro molecular organic compounds like humic substances or polycarboxylate based cement additives. The speciation of the formed complexes and the thermodynamic functions (log b0i(T), DRH0m,i, DRS0m,i) of the corresponding complexation reactions are determined as a function of temperature and ionic strength using Vis/NIR absorption spectroscopy. Additionaly, the structures of the NpO2+ complexes with oxalate, malonate, succinate and lactate are resolved by EXAFS spectroscopy, ATR-FT infrared spectroscopy and quantum chemical calculations revealing detailed information on the coordination properties of An(V) on a molecular level. In the second part the complexation of NpO2+ with the inorganic anions fluoride, chloride, nitrate and sulfate is studied at various temperatures and ionic strengths revealing the stoichiometry of the formed complexes and the thermodynamic functions of the respective complexation reactions. These inorganic anions are integral parts of natural groundwaters. Additionaly, fluoride and chloride are available in large quantities in salt rock formations which are in discussion as host rocks of nuclear waste repositories. In the third part of this work the NpO2+ complexation up to 200 °C is studied for the first time by absorption spectroscopy. Therefor, a high-temperature spectrophotometric cell is developed at the Institute for Nuclear Waste Disposal (INE) at the Karlsruhe Institute of Technology (KIT). The applicability of this setup for speciation studies up to 200 °C is demonstrated by studies on the complexation of NpO2+ with SO42-. The obtained results contribute to an improved understanding of the (geo)chemical behaviour of pentavalent actinides in aqueous systems and provide detailed information on the complexation properties of An(V) on a molecular level. Furthermore, the implementation of a high-temperature spectrophotometric cell for speciation studies on the complexation of NpO2+ up to 200 °C opens up the possibility for thermodynamic studies at conditions that might occur in the near-field of a nuclear waste repository

Advances in Signal Processing for Maritime Applications

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Genetic Variations of Interleukin-23R (1143A>G) and BPI (A645G), but Not of NOD2, Are Associated with Acute Graft-versus-Host Disease after Allogeneic Transplantation

Single nucleotide polymorphisms (SNPs) in genes of the immune system predict for aGVHD and mortality after allo-SCT. We investigated the effect of SNPs in the NOD2, BPI, and IL-23R genes on posttransplantation outcome in a cohort of 304 patients. NOD2 patient and donor genotype and BPI recipient genotype were not associated with the occurrence of aGVHD. However, IL-23R-SNP in the donor was correlated with less aGVHD. This association could be confirmed in multivariate analysis (odds ratio [OR], 0.39; P = .039), which identified in vivo T cell depletion (OR, 0.32; P < .001) and multiagent GVHD prophylaxis (OR, 0.51; P = .031) as other independent factors predicting for less-severe aGVHD. This multivariate model also revealed a trend toward less aGVHD in patients receiving a BPI G allele transplant (OR, 0.60; P = .067) and in those receiving a transplant from an HLA-matched donor (OR, 0.57; P = .058). In contrast, relapse was more frequent in patients with NOD2-SNPs (46.2% for SNP vs 33.2% for wild-type; P = .020). This association was found to be of borderline significance in multivariate analysis. Neither BPI nor IL-23R genotype predicted for relapse, and none of the investigated SNPs was correlated with 5-year overall survival. In our analysis, NOD2 SNPs did not predict aGVHD, but IL-23R(1142A>G) and BPI(A645G) SNPs appeared to be promising markers in this regard. The importance of these markers in prediction models for GVHD and relapse remain to be defined in large prospective clinical trials

Continuous Wave THz System Based on an Electrically Tunable Monolithic Dual Wavelength Y-Branch DBR Diode Laser

We analyse the use of a tunable dual wavelength Y-branch DBR laser diode for THz applications. The laser generates electrically tunable THz difference frequencies in the range between 100 and 300 GHz. The optical beats are tuned via current injection into a micro-resistor heater integrated on top of one of the distributed Bragg reflector (DBR) section of the diode. The laser is integrated in a homodyne THz system employing fiber coupled ion-implanted LT-GaAs log spiral antennas. The applicability of the developed system in THz spectroscopy is demonstrated by evaluating the spectral resonances of a THz filter as well as in THz metrology in thickness determination of a polyethylene sample