ORCID Profile
0000-0002-6549-9303
Current Organisations
Stanford University
,
European Organization for Nuclear Research
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Publisher: Springer Science and Business Media LLC
Date: 21-08-2017
Publisher: American Physical Society (APS)
Date: 03-05-2023
Publisher: Elsevier BV
Date: 02-2020
Publisher: Springer Netherlands
Date: 2009
Publisher: Springer Science and Business Media LLC
Date: 12-01-2021
Publisher: American Physical Society (APS)
Date: 11-07-2017
Publisher: SPIE
Date: 26-05-2022
DOI: 10.1117/12.2619794
Publisher: Oxford University Press (OUP)
Date: 30-12-2016
DOI: 10.1093/RPD/NCV505
Abstract: A systematic study of photon and neutron radiation doses generated in high-intensity laser-solid interactions is underway at SLAC National Accelerator Laboratory. These laser-solid experiments are being performed using a 25 TW (up to 1 J in 40 fs) femtosecond pulsed Ti:sapphire laser at the Linac Coherent Light Source's (LCLS) Matter in Extreme Conditions (MEC) facility. Radiation measurements were performed with passive and active detectors deployed at various locations inside and outside the target chamber. Results from radiation dose measurements for laser-solid experiments at SLAC MEC in 2014 with peak intensity between 10
Publisher: AIP Publishing
Date: 10-2016
DOI: 10.1063/1.4963906
Abstract: We describe the phase-contrast imaging instrument at the Matter in Extreme Conditions (MEC) endstation of the Linac Coherent Light Source. The instrument can image phenomena with a spatial resolution of a few hundreds of nanometers and at the same time reveal the atomic structure through X-ray diffraction, with a temporal resolution better than 100 fs. It was specifically designed for studies relevant to high-energy-density science and can monitor, e.g., shock fronts, phase transitions, or void collapses. This versatile instrument was commissioned last year and is now available to the MEC user community.
Publisher: OSA
Date: 2016
Publisher: Optica Publishing Group
Date: 26-02-2010
DOI: 10.1364/OE.18.005289
Publisher: The Optical Society
Date: 22-05-2019
DOI: 10.1364/AO.58.004220
Publisher: American Physical Society (APS)
Date: 28-06-2019
Publisher: IEEE
Date: 09-2012
Publisher: IOP Publishing
Date: 04-2022
Publisher: IEEE
Date: 05-2013
Publisher: The Optical Society
Date: 04-04-2012
DOI: 10.1364/OE.20.009099
Publisher: American Physical Society (APS)
Date: 05-01-2021
Publisher: AIP
Date: 2007
DOI: 10.1063/1.2768844
Publisher: IEEE
Date: 05-2007
Publisher: AIP Publishing
Date: 10-2017
DOI: 10.1063/1.5008289
Abstract: We study the feasibility of using small angle X-ray scattering (SAXS) as a new experimental diagnostic for intense laser-solid interactions. By using X-ray pulses from a hard X-ray free electron laser, we can simultaneously achieve nanometer and femtosecond resolution of laser-driven s les. This is an important new capability for the Helmholtz international beamline for extreme fields at the high energy density endstation currently built at the European X-ray free electron laser. We review the relevant SAXS theory and its application to transient processes in solid density plasmas and report on first experimental results that confirm the feasibility of the method. We present results of two test experiments where the first experiment employs ultra-short laser pulses for studying relativistic laser plasma interactions, and the second one focuses on shock compression studies with a nanosecond laser system.
Publisher: International Union of Crystallography (IUCr)
Date: 22-04-2015
DOI: 10.1107/S1600577515006244
Abstract: Ultrafast optical lasers play an essential role in exploiting the unique capabilities of recently commissioned X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS). Pump–probe experimental techniques reveal ultrafast dynamics in atomic and molecular processes and reveal new insights in chemistry, biology, material science and high-energy-density physics. This manuscript describes the laser systems and experimental methods that enable cutting-edge optical laser/X-ray pump–probe experiments to be performed at LCLS.
Publisher: Elsevier BV
Date: 2024
Publisher: American Physical Society (APS)
Date: 18-09-2006
Publisher: Wiley
Date: 16-02-2022
DOI: 10.1111/MAPS.13785
Publisher: IOP Publishing
Date: 06-11-2020
Publisher: Optica Publishing Group
Date: 2010
Abstract: We present three synchronously pumped Raman lasers generating picosecond visible laser pulses. Using KGW and diamond, we efficiently convert the wavelength of standard neodymium picosecond laser sources, as well as substantially compressing their pulse duration.
Publisher: The Optical Society
Date: 28-07-2011
DOI: 10.1364/OE.19.015538
Publisher: OSA
Date: 2009
Publisher: International Union of Crystallography (IUCr)
Date: 21-04-2015
DOI: 10.1107/S1600577515004865
Abstract: The LCLS beam provides revolutionary capabilities for studying the transient behavior of matter in extreme conditions. The particular strength of the Matter in Extreme Conditions instrument is that it combines the unique LCLS beam with high-power optical laser beams, and a suite of dedicated diagnostics tailored for this field of science. In this paper an overview of the beamline, the capabilities of the instrumentation, and selected highlights of experiments and commissioning results are presented.
Publisher: American Physical Society (APS)
Date: 03-08-2022
Publisher: AIP Publishing
Date: 10-2016
DOI: 10.1063/1.4966204
Publisher: Optica Publishing Group
Date: 10-09-2010
DOI: 10.1364/OE.18.020422
Publisher: American Physical Society (APS)
Date: 09-11-2021
Publisher: AIP Publishing
Date: 10-2017
DOI: 10.1063/1.4997756
Abstract: We measure the shock drive capabilities of a 30 J, nanosecond, 527 nm laser system at the matter in extreme conditions hutch of the Linac Coherent Light Source. Using a velocity interferometer system for any reflector, we ascertain the maximum instantaneous ablation pressure and characterize its dependence on a drive laser spot size, spatial profile, and temporal profile. We also examine the effects of these parameters on shock spatial and temporal uniformity. Our analysis shows the drive laser capable of generating instantaneous ablation pressures exceeding 160 GPa while maintaining a 1D shock profile. We find that slope pulses provide higher instantaneous ablation pressures than plateau pulses. Our results show instantaneous ablation pressures comparable to those measured at the Omega Laser Facility in Rochester, NY under similar optical drive parameters. Finally, we analyze how optical laser ablation pressures are compare with known scaling relations, accounting for variable laser wavelengths.
Publisher: Springer Science and Business Media LLC
Date: 16-11-2018
DOI: 10.1038/S41598-018-35260-3
Abstract: Bismuth has long been a prototypical system for investigating phase transformations and melting at high pressure. Despite decades of experimental study, however, the lattice-level response of Bi to rapid (shock) compression and the relationship between structures occurring dynamically and those observed during slow (static) compression, are still not clearly understood. We have determined the structural response of shock-compressed Bi to 68 GPa using femtosecond X-ray diffraction, thereby revealing the phase transition sequence and equation-of-state in unprecedented detail for the first time. We show that shocked-Bi exhibits a marked departure from equilibrium behavior - the incommensurate Bi-III phase is not observed, but rather a new metastable phase, and the Bi-V phase is formed at significantly lower pressures compared to static compression studies. We also directly measure structural changes in a shocked liquid for the first time. These observations reveal new behaviour in the solid and liquid phases of a shocked material and give important insights into the validity of comparing static and dynamic datasets.
Publisher: American Physical Society (APS)
Date: 04-08-2020
Publisher: IEEE
Date: 26-06-2023
Publisher: Optica Publishing Group
Date: 07-01-2009
DOI: 10.1364/OE.17.000569
Abstract: We demonstrate the operation of a continuous-wave (CW) picosecond yellow laser operating at 559 nm. A solid-state Raman laser using a KGW crystal was synchronously pumped by an 80 MHz laser operating at 532 nm. The output pulses were compressed from 10 ps at 532 nm down to 3.2 ps at 559 nm, strongly depending on the cavity length detuning. Slope efficiencies up to 42% were observed when the system was optimized for maximum output power. This technique can be extended to a range of visible wavelengths between 550-600 nm by using different Raman materials, and by cascaded conversion.
Publisher: AIP Publishing
Date: 05-2017
DOI: 10.1063/1.4982166
Abstract: Tuning the energy of an x-ray probe to an absorption line or edge can provide material-specific measurements that are particularly useful for interfaces. Simulated hard x-ray images above the Fe K-edge are presented to examine ion diffusion across an interface between Fe2O3 and SiO2 aerogel foam materials. The simulations demonstrate the feasibility of such a technique for measurements of density scale lengths near the interface with submicron spatial resolution. A proof-of-principle experiment is designed and performed at the Linac coherent light source facility. Preliminary data show the change of the interface after shock compression and heating with simultaneous fluorescence spectra for temperature determination. The results provide the first demonstration of using x-ray imaging at an absorption edge as a diagnostic to detect ultrafast phenomena for interface physics in high-energy-density systems.
Publisher: The Royal Society
Date: 24-06-2019
Abstract: In this article, we briefly summarize the experiments performed during the first run of the Advanced Wakefield Experiment, AWAKE, at CERN (European Organization for Nuclear Research). The final goal of AWAKE Run 1 (2013–2018) was to demonstrate that 10–20 MeV electrons can be accelerated to GeV energies in a plasma wakefield driven by a highly relativistic self-modulated proton bunch. We describe the experiment, outline the measurement concept and present first results. Last, we outline our plans for the future. This article is part of the Theo Murphy meeting issue ‘Directions in particle beam-driven plasma wakefield acceleration’.
Publisher: Informa UK Limited
Date: 17-01-2014
Publisher: IOP Publishing
Date: 13-11-2018
Publisher: AIP Publishing
Date: 08-2023
DOI: 10.1063/5.0157391
Abstract: Self-modulation is a beam–plasma instability that is useful to drive large- litude wakefields with bunches much longer than the plasma skin depth. We present experimental results showing that, when increasing the ratio between the initial transverse size of the bunch and the plasma skin depth, the instability occurs later along the bunch, or not at all, over a fixed plasma length because the litude of the initial wakefields decreases. We show cases for which self-modulation does not develop, and we introduce a simple model discussing the conditions for which it would not occur after any plasma length. Changing bunch size and plasma electron density also changes the growth rate of the instability. We discuss the impact of these results on the design of a particle accelerator based on the self-modulation instability seeded by a relativistic ionization front, such as the future upgrade of the Advanced WAKefield Experiment.
Publisher: JACoW Publishing, Geneva, Switzerland
Date: 2018
Publisher: Springer Science and Business Media LLC
Date: 20-01-2008
Publisher: Springer Science and Business Media LLC
Date: 10-07-2009
Publisher: IEEE
Date: 05-2007
Publisher: Optica Publishing Group
Date: 27-02-2008
DOI: 10.1364/OL.33.000491
Abstract: We report a dramatic improvement of the spatial coherence and beam ergence (0.66 mrad) of a 13.2 nm wavelength Ni-like Cd tabletop laser by injection seeding the soft x-ray laser lifier with high-harmonics pulses generated in a Ne gas jet. This phase coherent laser is an attractive light source for at-wavelength interferometry of extreme ultraviolet lithography optics and other applications.
Publisher: AIP Publishing
Date: 25-03-2019
DOI: 10.1063/1.5085678
Abstract: X-ray free electron laser (XFEL) sources have revolutionized our capability to study ultrafast material behavior. Using an XFEL, we revisit the structural dynamics of shock compressed bismuth, resolving the transition sequence on shock release in unprecedented details. Unlike previous studies that found the phase-transition sequence on shock release to largely adhere to the equilibrium phase diagram (i.e., Bi-V → Bi-III → Bi-II → Bi-I), our results clearly reveal previously unseen, non-equilibrium behavior at these conditions. On pressure release from the Bi-V phase at 5 GPa, the Bi-III phase is not formed but rather a new metastable form of Bi. This new phase transforms into the Bi-II phase which in turn transforms into a phase of Bi which is not observed on compression. We determine this phase to be isostructural with β-Sn and recover it to ambient pressure where it exists for 20 ns before transforming back to the Bi-I phase. The structural relationship between the tetragonal β-Sn phase and the Bi-II phase (from which it forms) is discussed. Our results show the effect that rapid compression rates can have on the phase selection in a transforming material and show great promise for recovering high-pressure polymorphs with novel material properties in the future.
Publisher: Optica Publishing Group
Date: 26-05-2009
DOI: 10.1364/OL.34.001660
Abstract: We report mode-locked operation of a synchronously pumped Ce:LiCAF oscillator. The laser operated in the deep UV with output radiation centered at 291 nm and a pulse duration of 6 ps. The maximum output power measured was 52 mW, with 13% slope efficiency. The Ce:LiCAF crystal has a gain bandwidth capable of supporting few-femtosecond pulses, and so our results demonstrate the potential to form a new class of ultrafast lasers operating directly at deep UV wavelengths.
Publisher: American Physical Society (APS)
Date: 20-04-2021
Publisher: AIP Publishing
Date: 11-04-2022
DOI: 10.1063/5.0088592
Abstract: We report on the generation and tuning of single-frequency laser light in a monolithic Fabry–Pérot diamond Raman resonator operating in the visible spectral range. The device was capable of squeezing the linewidth of a broad multi-mode nanosecond pump laser (Δνp= 7.2 ± 0.9 GHz at λp= 450 nm) to a nearly Fourier-limited single axial mode Stokes pulse (ΔνS= 114 ± 20 MHz at λS= 479 nm). The tuning was achieved by precise adjustment of the resonator temperature, with a measured frequency-temperature tuning slope of ∂ν0/∂T≈ −3 GHz/K, and a temperature dependence of the first-order Raman phonon line of ∂νR/∂T≈ +0.23 GHz/K. The Stokes center frequency was tuned continuously for over 20 GHz (more than twice the free spectral range of the resonator), which, in combination with the broad Ti:Sapphire laser spectral tunability, enables the production of Fourier-limited pulses in the 400–500 nm spectral range. The Stokes center-frequency fluctuations were 52 MHz (RMS) when the temperature of the resonator was actively stabilized. Moreover, the conversion efficiency was up to 30%, yielding an overall power spectral density enhancement of & × from pump to Stokes pulse.
Publisher: IOP Publishing
Date: 28-12-2022
Publisher: Optica Publishing Group
Date: 17-03-2022
Abstract: Fourier-limited nanosecond pulses featuring narrow spectral bandwidths are required for applications in spectroscopy, sensing, and quantum optics. Here, we demonstrate a direct and simple route for the generation of single-frequency light relying on phonon-resonant Raman interactions within a monolithic diamond resonator. The technique enables the production of nearly Fourier-limited nanosecond optical pulses (15 ns), with an overall spectral bandwidth of down to 180 MHz, which is nearly two orders of magnitude narrower than the pump laser linewidth used (12 GHz). The power conversion efficiency was 47%, yielding a power spectral brightness enhancement of --> 50 × compared to the pump. Our results pave the way to the integration of pulsed widely tunable, power scalable, narrow linewidth light sources into integrated photonic platforms. Furthermore, the device does not need elaborate mechanical feedback loops for cavity length or frequency stabilization, or any additional optical components.
Publisher: The Optical Society
Date: 06-08-2019
DOI: 10.1364/OL.44.003924
Publisher: IOP Publishing
Date: 12-09-2012
Publisher: Elsevier BV
Date: 2023
Publisher: arXiv
Date: 2022
Publisher: The Optical Society
Date: 14-04-2014
DOI: 10.1364/OL.39.002487
Publisher: American Physical Society (APS)
Date: 08-02-2019
Publisher: IOP Publishing
Date: 22-04-2016
Publisher: American Physical Society (APS)
Date: 08-02-2019
Publisher: Springer Science and Business Media LLC
Date: 24-09-2018
DOI: 10.1038/S41598-018-32520-0
Abstract: We demonstrate a rapid, accurate, and convenient method for tailoring the optical properties of diamond surfaces by employing laser induced periodic surface structuring (LIPSSs). The characteristics of the fabricated photonic surfaces were adjusted by tuning the laser wavelength, number of impinging pulses, angle of incidence and polarization state. Using Finite Difference Time Domain (FDTD) modeling, the optical transmissivity and bandwidth was calculated for each fabricated LIPSSs morphology. The highest transmission of ~99.5% was obtained in the near-IR for LIPSSs structures with aspect ratios of the order of ~0.65. The present technique enabled us to identify the main laser parameters involved in the machining process, and to control it with a high degree of accuracy in terms of structure periodicity, morphology and aspect ratio. We also demonstrate and study the conditions for fabricating spatially coherent nanostructures over large areas maintaining a high degree of nanostructure repeatability and optical performance. While our experimental demonstrations have been mainly focused on diamond anti-reflection coatings and gratings, the technique can be easily extended to other materials and applications, such as integrated photonic devices, high power diamond optics, or the construction of photonic surfaces with tailored characteristics in general.
Publisher: Optica Publishing Group
Date: 02-08-2022
DOI: 10.1364/OL.464816
Abstract: Pulsed spectrally pure light is required for applications in high-resolution spectroscopy, optical coherent communications, and quantum technologies. In this work, we report on the efficient generation of high peak power, single-frequency, and tunable nanosecond pulses utilizing stimulated scattering, with an increased spectral brightness by exploiting double resonances in an integrated diamond Raman resonator. The device is based on a miniature monolithic Fabry–Perot design pumped by a milliwatt-class average power Q-switched single-frequency pulsed laser at 532 nm. Our device was capable of enhancing the peak spectral brightness by greater than three times compared with conventional singly resonant diamond Raman lasers by tuning the effective resonator length at pump and Stokes wavelengths simultaneously. Our results facilitate the integration of pulsed and power scalable single frequency sources into hybrid photonic integrated platforms with a broad range of applications.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 20-10-2023
Publisher: American Physical Society (APS)
Date: 05-02-2020
Publisher: Frontiers Media SA
Date: 22-07-2022
Publisher: Frontiers Media SA
Date: 24-03-2022
Publisher: American Physical Society (APS)
Date: 06-02-2009
Publisher: American Physical Society (APS)
Date: 08-01-2019
Publisher: AIP Publishing
Date: 09-2023
DOI: 10.1063/4.0000207
Publisher: Optica Publishing Group
Date: 2010
Abstract: We demonstrate for the first time that the DUV laser material cerium LiCAF can be mode locked to produce picosecond pulses in this hard to access spectral range, and we discuss the potential to directly generate sub femtosecond pulses.
Publisher: American Physical Society (APS)
Date: 09-01-2017
Publisher: OSA
Date: 2012
Publisher: Walter de Gruyter GmbH
Date: 17-10-2023
Publisher: The Optical Society
Date: 28-02-2013
DOI: 10.1364/OL.38.000796
Publisher: AIP Publishing
Date: 05-2015
DOI: 10.1063/1.4920943
Publisher: American Physical Society (APS)
Date: 10-2021
Publisher: Springer Science and Business Media LLC
Date: 05-2022
Publisher: OSA
Date: 2019
Publisher: Springer Science and Business Media LLC
Date: 29-08-2018
Publisher: Optica Publishing Group
Date: 12-2008
Publisher: American Physical Society (APS)
Date: 31-12-2019
Publisher: Elsevier BV
Date: 07-2019
Publisher: Optica Publishing Group
Date: 11-02-2010
DOI: 10.1364/OL.35.000556
Publisher: OSA
Date: 2007
Publisher: Springer Science and Business Media LLC
Date: 14-03-2016
DOI: 10.1038/NCOMMS10970
Abstract: The shock-induced transition from graphite to diamond has been of great scientific and technological interest since the discovery of microscopic diamonds in remnants of explosively driven graphite. Furthermore, shock synthesis of diamond and lonsdaleite, a speculative hexagonal carbon polymorph with unique hardness, is expected to happen during violent meteor impacts. Here, we show unprecedented in situ X-ray diffraction measurements of diamond formation on nanosecond timescales by shock compression of pyrolytic as well as polycrystalline graphite to pressures from 19 GPa up to 228 GPa. While we observe the transition to diamond starting at 50 GPa for both pyrolytic and polycrystalline graphite, we also record the direct formation of lonsdaleite above 170 GPa for pyrolytic s les only. Our experiment provides new insights into the processes of the shock-induced transition from graphite to diamond and uniquely resolves the dynamics that explain the main natural occurrence of the lonsdaleite crystal structure being close to meteor impact sites.
Publisher: AIP Publishing
Date: 05-2015
DOI: 10.1063/1.4921407
Publisher: American Physical Society (APS)
Date: 07-09-2021
Publisher: AIP Publishing
Date: 15-08-2016
DOI: 10.1063/1.4959792
Abstract: We present the first spectrally resolved measurements of x-rays scattered from cryogenic hydrogen jets in the single photon counting limit. The 120 Hz capabilities of the LCLS, together with a novel hydrogen jet design [J. B. Kim et al., Rev. Sci. Instrum. (these proceedings)], allow for the ability to record a near background free spectrum. Such high-dynamic-range x-ray scattering measurements enable a platform to study ultra-fast, laser-driven, heating dynamics of hydrogen plasmas. This measurement has been achieved using two highly annealed pyrolytic graphite crystal spectrometers to spectrally resolve 5.5 keV x-rays elastically and inelastically scattered from cryogenic hydrogen and focused on Cornell-SLAC pixel array detectors [S. Herrmann et al., Nucl. Instrum. Methods Phys. Res., Sect. A 718, 550 (2013)].
Publisher: Elsevier BV
Date: 08-2021
Publisher: Optica Publishing Group
Date: 2020
DOI: 10.1364/CLEOPR.2020.C6A_3
Abstract: We demonstrate a Raman laser continuously tunable in the visible range, capable of performing element-selective photo-ionization. The Stokes outputs exhibited a linewidth of 11.0 ± 1.0 GHz with a conversion efficiency of more than 60%. © 2020 The Authors
Publisher: Springer Science and Business Media LLC
Date: 13-01-2022
Publisher: Acta Naturae Ltd
Date: 27-10-2020
Publisher: Springer Science and Business Media LLC
Date: 26-05-2020
DOI: 10.1038/S41467-020-16426-Y
Abstract: The gas and ice giants in our solar system can be seen as a natural laboratory for the physics of highly compressed matter at temperatures up to thousands of kelvins. In turn, our understanding of their structure and evolution depends critically on our ability to model such matter. One key aspect is the miscibility of the elements in their interiors. Here, we demonstrate the feasibility of X-ray Thomson scattering to quantify the degree of species separation in a 1:1 carbon–hydrogen mixture at a pressure of ~150 GPa and a temperature of ~5000 K. Our measurements provide absolute values of the structure factor that encodes the microscopic arrangement of the particles. From these data, we find a lower limit of $$2{4}_{-7}^{+6}$$ 2 4 − 7 + 6 % of the carbon atoms forming isolated carbon clusters. In principle, this procedure can be employed for investigating the miscibility behaviour of any binary mixture at the high-pressure environment of planetary interiors, in particular, for non-crystalline s les where it is difficult to obtain conclusive results from X-ray diffraction. Moreover, this method will enable unprecedented measurements of mixing/demixing kinetics in dense plasma environments, e.g., induced by chemistry or hydrodynamic instabilities.
Publisher: MDPI AG
Date: 26-05-2021
DOI: 10.3390/MIN11060567
Abstract: Natural kamacite s les (Fe92.5Ni7.5) from a fragment of the Gibeon meteorite were studied as a proxy material for terrestrial cores to examine phase transition kinetics under shock compression for a range of different pressures up to 140 GPa. In situ time-resolved X-ray diffraction (XRD) data were collected of a body-centered cubic (bcc) kamacite section that transforms to the high-pressure hexagonal close-packed (hcp) phase with sub-nanosecond temporal resolution. The coarse-grained crystal of kamacite rapidly transformed to highly oriented crystallites of the hcp phase at maximum compression. The hcp phase persisted for as long as 9.5 ns following shock release. Comparing the c/a ratio with previous static and dynamic work on Fe and Fe-rich Fe-Ni alloys, it was found that some shots exhibit a larger than ideal c/a ratio, up to nearly 1.65. This work represents the first time-resolved laser shock compression structural study of a natural iron meteorite, relevant for understanding the dynamic material properties of metallic planetary bodies during impact events and Earth’s core elasticity.
Publisher: Optica Publishing Group
Date: 10-03-2020
DOI: 10.1364/OE.384630
Abstract: We demonstrate a continuously tunable, multi-Stokes Raman laser operating in the visible range (420 - 600 nm). Full spectral coverage was achieved by efficiently cascading the Raman shifted output of a tunable, frequency-doubled Ti:Sapphire laser. Using an optimized hemi-spherical external Raman cavity composed only of a diamond crystal and a single reflecting mirror, producing high power output at high conversion efficiency ( % from pump to Stokes) for a broad range of wavelengths across the visible. Enhancement of the cascading was achieved by controlling the polarization state of the pump and Stokes orders. The Stokes outputs exhibited a linewidth of 11 ± 1 GHz for each order, resembling the pump laser linewidth, enabling its use for the intended spectroscopic applications. Furthermore, the Raman laser performance was demonstrated by applying it for the resonance excitation of atomic transitions in calcium.
Publisher: AIP Publishing
Date: 26-09-2014
DOI: 10.1063/1.4896175
Abstract: We have developed a new experimental platform at the Linac Coherent Light Source (LCLS) which combines simultaneous angularly and spectrally resolved x-ray scattering measurements. This technique offers a new insights on the structural and thermodynamic properties of warm dense matter. The & 50 fs temporal duration of the x-ray pulse provides near instantaneous snapshots of the dynamics of the compression. We present a proof of principle experiment for this platform to characterize a shock-compressed plastic foil. We observe the disappearance of the plastic semi-crystal structure and the formation of a compressed liquid ion-ion correlation peak. The plasma parameters of shock-compressed plastic can be measured as well, but requires an averaging over a few tens of shots.
Publisher: AIP Publishing
Date: 08-2022
DOI: 10.1063/5.0085297
Publisher: IOP Publishing
Date: 11-2021
Publisher: The Optical Society
Date: 12-07-2011
DOI: 10.1364/OME.1.000576
Publisher: MDPI AG
Date: 12-08-2022
DOI: 10.3390/SYM14081680
Abstract: Plasma wakefield acceleration is a promising technology to reduce the size of particle accelerators. The use of high energy protons to drive wakefields in plasma has been demonstrated during Run 1 of the AWAKE programme at CERN. Protons of energy 400 GeV drove wakefields that accelerated electrons to 2 GeV in under 10 m of plasma. The AWAKE collaboration is now embarking on Run 2 with the main aims to demonstrate stable accelerating gradients of 0.5–1 GV/m, preserve emittance of the electron bunches during acceleration and develop plasma sources scalable to 100s of metres and beyond. By the end of Run 2, the AWAKE scheme should be able to provide electron beams for particle physics experiments and several possible experiments have already been evaluated. This article summarises the programme of AWAKE Run 2 and how it will be achieved as well as the possible application of the AWAKE scheme to novel particle physics experiments.
Publisher: SPIE
Date: 13-09-2007
DOI: 10.1117/12.734285
Publisher: The Optical Society
Date: 19-05-2011
DOI: 10.1364/OE.19.010857
Publisher: Springer Science and Business Media LLC
Date: 12-03-2019
DOI: 10.1038/S41598-019-40782-5
Abstract: We investigated the high-pressure behavior of polyethylene (CH 2 ) by probing dynamically-compressed s les with X-ray diffraction. At pressures up to 200 GPa, comparable to those present inside icy giant planets (Uranus, Neptune), shock-compressed polyethylene retains a polymer crystal structure, from which we infer the presence of significant covalent bonding. The A 2 /m structure which we observe has previously been seen at significantly lower pressures, and the equation of state measured agrees with our findings. This result appears to contrast with recent data from shock-compressed polystyrene (CH) at higher temperatures, which demonstrated demixing and recrystallization into a diamond lattice, implying the breaking of the original chemical bonds. As such chemical processes have significant implications for the structure and energy transfer within ice giants, our results highlight the need for a deeper understanding of the chemistry of high pressure hydrocarbons, and the importance of better constraining planetary temperature profiles.
Publisher: AIP Publishing
Date: 08-06-2020
DOI: 10.1063/5.0013085
Abstract: We determine the strength of laser shock-compressed polycrystalline diamond at stresses above the Hugoniot elastic limit using a technique combining x-ray diffraction from the Linac Coherent Light Source with velocity interferometry. X-ray diffraction is used to measure lattice strains, and velocity interferometry is used to infer shock and particle velocities. These measurements, combined with density-dependent elastic constants calculated using density functional theory, enable determination of material strength above the Hugoniot elastic limit. Our results indicate that diamond retains approximately 20 GPa of strength at longitudinal stresses of 150–300 GPa under shock compression.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 03-2019
Abstract: We image a previously unidentified ultrafast lattice response in silicon, providing insight into deformation kinetics.
Publisher: AIP Publishing
Date: 05-2018
DOI: 10.1063/1.5017908
Abstract: Diamond formation in polystyrene (C8H8)n, which is laser-compressed and heated to conditions around 150 GPa and 5000 K, has recently been demonstrated in the laboratory [Kraus et al., Nat. Astron. 1, 606–611 (2017)]. Here, we show an extended analysis and comparison to first-principles simulations of the acquired data and their implications for planetary physics and inertial confinement fusion. Moreover, we discuss the advanced diagnostic capabilities of adding high-quality small angle X-ray scattering and spectrally resolved X-ray scattering to the platform, which shows great prospects of precisely studying the kinetics of chemical reactions in dense plasma environments at pressures exceeding 100 GPa.
Publisher: The Royal Society
Date: 23-12-2019
Publisher: American Physical Society (APS)
Date: 06-07-2022
Publisher: Optica Publishing Group
Date: 22-12-2020
DOI: 10.1364/OE.413098
Abstract: We describe a theoretical approach based on Müller and tensor calculus for predicting the polarization state and gain of cascaded Stokes orders produced under coherent Raman scattering regime conditions. The formulation follows a Markovian-style implementation for F 2 g -type modes in Raman cubic crystals. The theoretical model is supported by experimental results that corroborate that the polarization and power of the cascaded Stokes orders can be effectively predicted using sequential calculus. We extend these results to a variety of crystal propagation directions, with the aim of facilitating the design of advanced solid-state Raman lasers.
Publisher: American Physical Society (APS)
Date: 08-10-2012
Publisher: AIP Publishing
Date: 04-01-2019
DOI: 10.1063/1.5070140
Abstract: We present measurements of the plasmon shift in shock-compressed matter as a function of momentum transfer beyond the Fermi wavevector using an X-ray Free Electron Laser. We eliminate the elastically scattered signal retaining only the inelastic plasmon signal. Our plasmon dispersion agrees with both the random phase approximation (RPA) and static Local Field Corrections (sLFC) for an electron gas at both zero and finite temperature. Further, we find the inclusion of electron-ion collisions through the Born-Mermin Approximation (BMA) to have no effect. Whilst we cannot distinguish between RPA and sLFC within our error bars, our data suggest that dynamic effects should be included for LFC and provide a route forward for higher resolution future measurements.
Publisher: Springer Science and Business Media LLC
Date: 27-11-2018
DOI: 10.1038/S41598-018-36259-6
Abstract: A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.
Publisher: Optica Publishing Group
Date: 06-2022
DOI: 10.1364/OME.458774
Abstract: We study the propagation of coherent broadband light through laser induced periodic surface structures (LIPSS) fabricated on diamond surfaces. 3D finite-difference time-domain (FDTD) simulations were carried out for a variety of experimentally produced LIPSS morphologies, which include the specific nanometer-scale mesoscopic irregularities arising from the fabrication technique. We compare their performance with sinusoidal grating-like structures, showing that the specific features present in LIPSS nanoripples produce a considerable scattering and diffraction when compared to the ideal nanostructures. With a view on determining the scope of the potential optical and photonic applications of LIPSS, we evaluate the effect of these irregularities on the transmitted spatial beam quality and the spatial phase characteristics of the optical wavefront in a broad spectral range.
Publisher: IEEE
Date: 05-2008
Publisher: American Physical Society (APS)
Date: 12-08-2013
Publisher: IEEE
Date: 06-2009
Publisher: AIP Publishing
Date: 18-07-2016
DOI: 10.1063/1.4959256
Abstract: We present results from time-resolved X-ray imaging and inelastic scattering on collective excitations. These data are then employed to infer the mass density evolution within laser-driven shock waves. In our experiments, thin carbon foils are first strongly compressed and then driven into a dense state by counter-propagating shock waves. The different measurements agree that the graphite s le is about twofold compressed when the shock waves collide, and a sharp increase in forward scattering indicates disassembly of the s le 1 ns thereafter. We can benchmark hydrodynamics simulations of colliding shock waves by the X-ray scattering methods employed.
Publisher: IEEE
Date: 06-2009
Publisher: American Physical Society (APS)
Date: 24-02-2020
Publisher: American Physical Society (APS)
Date: 14-12-2018
Publisher: American Physical Society (APS)
Date: 28-12-2020
Publisher: Author(s)
Date: 2017
DOI: 10.1063/1.4975847
Publisher: EDP Sciences
Date: 2013
Publisher: The Optical Society
Date: 22-06-2017
DOI: 10.1364/OE.25.015330
Location: United States of America
No related grants have been discovered for Eduardo Granados.