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.

Kerr-Lens Mode-Locked Middle IR Polycrystalline Cr:ZnS Laser with a Repetition Rate 1.2 GHz

Abstract: We report flexible design of femtosecond middle-IR lasers with a broad range of repetition rates 0.08–1.2 GHz. The lasers emit few-cycle pulses with 4–16.4 THz bandwidth, 0.1– 21 nJ energy at 2.4 µm wavelength.

Integrated inversion of subsurface velocity structures using wave equation tomography and full waveform inversion

Abstract: Summary We propose to use wave-equation tomography (WET) method to build long-wavelength velocity structure for full waveform inversion (FWI). In WET, full wavefield modeling is performed and cross-correlation time delay between the arrivals from synthetic and real waveforms is used as objective function. Adjoint method is used to calculate the gradient in each iteration efficiently. Since WET and FWI share similar inversion structure, we use a hybrid misfit function to combine the two methods as an integrated workflow that is able to estimate high-resolution structure from poor starting model. To stabilize WET and make it converge to global minimum, we precondition the time delay measures with maximum cross-correlation coefficients and perform adaptive scale smoothing to the gradients. By exploring the band-limited feature of seismic wavefield, WET can provide better resolution than raybased travel time tomography, which is under high frequency approximation. To illustrate the advantage of wave-equation tomography, we show in a 2D synthetic test that WET provides subsurface information that is critical for successful FWI. We also test 2D Marmousi model and satisfactory inversion results are achieved without much manual manipulating.

Progress in quantitative elemental analyses in high P-T fluids using synchrotron x-ray fluorescence (SXRF)

Abstract: Two different experimental set-ups have been installed at ID22 beamline (ESRF) for synchrotron x-ray fluorescence (SXRF) analyses in diamond anvil cells (DACs). The set-ups differ from each other by the incident energy, the focusing device and the collection geometry. Analyses of standard aqueous solutions containing well-known concentrations of Sr and Rb have been performed in both experimental configurations and the detection limits (DLs) determined. The most important factors contributing to both the fluorescence intensity yield and the background have been discussed in order to determine the experimental configuration providing the lowest detection limits. The limiting factor for the analyses at very low concentrations is the background arising from the Compton and Rayleigh scattering in the diamond anvils, which have a major contribution in the collection geometry imposed by the design of the DAC. We show that slight improvements of this design enable the acquisition of the fluorescence at 150°, permitting SXRF analyses of aqueous solutions to be performed at the 40 ppm level in a standard DAC working to 10 GPa and 600 °C, at least.

Multiple wavelength raman laser

Abstract: A pulsed laser system may include a Raman fiber that is configured to act as multiple wavelength Raman laser. The fiber is configured to receive a pulsed input beam from an input source and convert the input beam to an output beam having narrow band outputs at first and second frequencies v1 and v2.

Seismological and mineralogical constraints on the inner core fabric

Abstract: [1] Under the assumption of lattice preferred orientation of iron hcp crystals, the seismic anisotropy of the inner core is related to single crystal elastic properties by a fabric model. This model is able to explain a new seismological constraint: the constant behaviour of the ratio k of two anisotropy coefficients, despite radial and lateral variations of the anisotropy level in the inner core. The relevance of the theoretical calculations of iron single crystal elastic properties at inner core conditions are tested by a comparison between seismic estimates and computed values of this ratio k. Taking into account the error bar of the seismic estimate, iron hcp structures presenting fast and slow c axis could fit the data equally well.