5 research outputs found
Eye-Safe Solid-State Quasi-CW Raman Laser with Millisecond Pulse Duration
We demonstrate the first quasi-CW (ms-long pulses, pump duty cycle of 10%)
end-diode pumped solid state laser generating eye-safe radiation via
intracavity Raman conversion. The output power at the first Stokes wavelength
(1524 nm) was 250 mW. A theoretical model was applied to analyze the laser
system and provide routes for optimization. The possibility of true CW
operation was discussed.Comment: Preprint accepted for publication in Optics Communications on Feb 6,
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Ultrafast domain dilation induced by optical pumping in ferromagnetic CoFe/Ni multilayers
Ultrafast optical pumping of systems with spatially nonuniform magnetic
textures is known to cause far-from-equilibrium spin transport effects, such as
the broadening of domain-walls. Here, we study the dynamics of labyrinth domain
networks in ferromagnetic CoFe/Ni multilayers subject to a femtosecond optical
pump and find an ultrafast domain dilation by 6% within 1.6 ps. This surprising
result is based on the unambiguous determination of a harmonically-related
shift of ultrafast magnetic X-ray diffraction for the first- and third-order
rings. Domain dilation is plausible from conservation of momentum arguments,
whereby inelastic scattering from a hot, quasi-ballistic, radial current
transfers momentum to the magnetic domains. Our results suggest a potentially
rich variety of unexpected physical phenomena associated with
far-from-equilibrium inelastic electron-magnon scattering processes in the
presence of spin textures
Controlling the polarization and vortex charge of attosecond high-harmonic beams via simultaneous spin–orbit momentum conservation
[EN]Optical interactions are governed by both spin and angular momentum conservation laws, which serve as a tool for controlling light–matter interactions or elucidating electron dynamics and structure of complex systems. Here, we uncover a form of simultaneous spin and orbital angular momentum conservation and show, theoretically and experimentally, that this phenomenon allows for unprecedented control over the divergence and polarization of extreme-ultraviolet vortex beams. High harmonics with spin and orbital angular momenta are produced, opening a novel regime of angular momentum conservation that allows for manipulation of the polarization of attosecond pulses—from linear to circular—and for the generation of circularly polarized vortices with tailored orbital angular momentum, including harmonic vortices with the same topological charge as the driving laser beam. Our work paves the way to ultrafast studies of chiral systems using high-harmonic beams with designer spin and orbital angular momentum.The authors are thankful for useful and productive conversations with E. Pisanty, C. Durfee, D. Hickstein, S. Alperin and M. Siemens. H.C.K. and M.M.M. graciously acknowledge support from the Department of Energy BES Award No. DE-FG02–99ER14982 for the experimental implementation, as well as a MURI grant from the Air Force Office of Scientific Research under Award No. FA9550–16–1–0121 for the theory. J.L.E., N.J.B. and Q.L.N. acknowledge support from National Science Foundation Graduate Research Fellowships (Grant No. DGE-1144083). C.H.-G., J.S.R. and L.P. acknowledge support from Junta de Castilla y LeĂłn (SA046U16) and Ministerio de EconomĂa y Competitividad (FIS2013–44174-P, FIS2016–75652-P). C.H.-G. acknowledges support from a 2017 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation. L.R. acknowledges support from Ministerio de EducaciĂłn, Cultura y Deporte (FPU16/02591). A.P. acknowledges support from the Marie Sklodowska-Curie Grant, Agreement No. 702565. We thankfully acknowledge the computer resources at MareNostrum and the technical support provided by Barcelona Supercomputing Center (RES-AECT-2014–2–0085). This research made use of the high-performance computingresources of the Castilla y LeĂłn Supercomputing Center (SCAYLE, www.scayle.es),financed by the European Regional Development Fund (ERDF). Certain commercial instruments are identified to specify the experimental study adequately. This does not imply endorsement by the National Institute of Standards and Technology (NIST) or that the instruments are the best available for the purpose