IPG Photonics

About: IPG Photonics is a based out in . It is known for research contribution in the topics: Laser & Fiber laser. The organization has 903 authors who have published 1241 publications receiving 63339 citations.

Correlation of Terrestrial Climatic Fluctuations with Global Signals During the Upper Cretaceous–Danian in a Compressive Setting (Provence, France)

Abstract: The Upper Cretaceous-lower Paleocene terrestrial formations from the Aix-en-Provence basin offer a high-resolution record of the effects of climate changes. These units were deposited in a basin with low topographic relief under climate conditions that varied from subhumid to semiarid. Sedimentation during subhumid periods was characterized by accumulation of carbonate mud in the main lake and aggradation of floodplains during overbank floods. Carbonate-rich paleosols, which occur throughout the subhumid succession, contain authigenic minerals with interstratified illite–smectite and smectite. Although subhumid conditions were dominant during deposition, the occurrence of five semiarid episodes can be documented on the basis of facies, paleomagnetic signal, and mineralogic associations of rocks deposited across the paleolandscape. The lake-margin environment was most sensitive to climate change. Dolomite and gypsum crystals, authigenic smectite and palygorskite, and secondary fine-grained hematite grew within rocks deposited along the lake margin under semiarid conditions. The mineralogic transformations resulted in a distinct paleomagnetic record composed of a It component (200 to 400°C) and an associated chemo-detrital ht component (up to 600°C). During the semiarid episodes, sedimentation in floodplain environments was reduced, allowing development of mature smectite or smectite–palygorskite paleosols. Semiarid episode 1 occurs within the Calcaire de Rognac Formation, semiarid episodes 2 and 3 lie within the Upper Argiles Rutilantes Formation, and semiarid episodes 4 and 5 are just below and within the Calcaire de Vitrolles Formation. Recognition of correlative deposits with a distinct paleomagnetic signal allows correlation between the continental successions of Provence and the geomagnetic polarity time scale. The lithostratigraphic units, as well as the distribution of dinosaur oospecies are largely diachronous, representing a few millions of years. Semiarid episodes 1 to 3 occurred during the Early Maastrichtian. No semiarid episodes are recorded for the cooler interval that defined the Middle–Late Maastrichtian. Semiarid episodes 4 and 5 correspond to the warmer periods that preceded and followed the 500-ky-long interval containing the Cretaceous–Tertiary boundary.

SM green fiber laser operating in CW and QCW regimes and producing over 550W of average output power

Abstract: We report a single-mode (SM) green laser based on single-pass frequency doubling of a linearly-polarized narrowlinewidth Yb fiber laser in LBO crystal, and configured to operate in a range of regimes from continuous-wave (CW) to high-repetition-rate quasi-continuous-wave (QCW). Adjusting the duty cycle, we maintained high second harmonic generation (SHG) efficiency for various output powers. Average powers of over 550W in QCW and over 350W in CW regimes were obtained with the wall-plug efficiency up to 15%, opening the possibility to creating new class of simple, compact and efficient single-mode green lasers with output power up to 1kW and above. The same approach could also be used to create high-power lasers operating at other wavelengths in ultraviolet and visible spectral ranges.

Water and the compressibility of silicate glasses: A Brillouin spectroscopic study

Abstract: The compressional and shear wave velocities of seven series of hydrous aluminosilicate glasses were measured by Brillouin scattering at room temperature and pressure as a function of water content. The glasses were quenched from high temperature and 0.2 or 0.3 GPa pressure. The dry end-members range from highly polymerized albitic and granitic compositions, to depolymerized synthetic analogues of mantle-derived melts. For each set of glasses, the adiabatic shear and bulk moduli have been calculated from the measured sound velocities and densities. These moduli are linear functions of water content up to 5 wt% H2O, the highest concentration investigated, indicating that both are independent of water speciation in all series. For anhydrous glasses, (∂ V /∂ P )S changes from about −0.3 to −0.7 × 10−15 m3/(Pa·mol) with increasing degree of polymerization. For the same compositions, the partial molar (∂ V /∂ P )S of the water component changes from near zero to −0.8 × 10−15 m3/(Pa·mol) with increasing degree of polymerization, such that dissolved water amplifies the differences in rigidity between the anhydrous glasses. This strong variation indicates that the solubility mechanisms of water depend strongly on silicate composition. A simple linear model reproduces (∂ V /∂ P )S to within measurement uncertainty, with glasses becoming more compressible as NBO/T decreases and as alkalinity increases. The dissolved water component also becomes more compressible as NBO/T decreases, but less compressible as alkalinity increases. In strongly depolymerized structures, water causes an increase in sound velocities even though it induces a decrease in density. The general rule according to which sound velocities correlate with density is, therefore, violated, for in these cases water dissolution results in a decrease of compressibility. Barring any strongly anomalous effect of water on configurational compressibility, the trends observed for glasses should be still more divergent for melts. Consequently, hydrous mafic and ultramafic liquids are predicted to have a very low compressibility. The shear modulus of hydrous glasses varies little with bulk composition or water content, supporting the use of a single composition-independent pre-exponential factor in models of melt viscosity.

Structural transformation in Ni-bearing Na2Si2O5 glass and melt

Abstract: The coordination environment around Ni at minor concentration levels (2 wt. % NiO) in Na2Si2O5 glass and melt (293–1250K) has been investigated by Ni K-edge X-ray Absorption Fine Structure (XAFS) spectroscopy. X-ray Absorption Near Edge Structure (XANES) spectra indicate that both IVNi and VNi occur in the glass, whereas IVNi is dominant in the melt. The average anharmonic Ni-O distances derived from XAFS spectra of the glass at 293 K and the melt above 1150 K are 2.00 (±0.02) and 1.97 (± 0.02) A, respectively. The Ni-O distance in the glass is consistent with a mixture of IVNi and VNi, whereas that in the melt is consistent with dominantly IVNi, suggesting a Ni-coordination change during glass melting. This major change in Ni coordination indicates significant reorganization of the melt during quenching and crystallization. These observations for a compositionally-simple melt/glass system may help explain the enrichment of Ni in early-formed igneous minerals. They also suggest the possibility of a pressure-induced coordination change around Ni in the mantle which may influence geochemical modeling of the deep Earth.