Sökning: "transient grating"

Visar resultat 1 - 5 av 7 avhandlingar innehållade orden transient grating.

  1. 1. Ultrafast spin, lattice, and electron dynamics in thin metallic films : in the terahertz, near-infrared, and extreme ultraviolet regimes

    Författare :Vivek Unikandanunni; Stefano Bonetti; Andreas Rydh; Jurgen Lindner; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Terahertz; near-infrared; extreme ultraviolet; epitaxial cobalt; transient grating; field emission; gold; platinum; electron-phonon coupling; magneto-crystalline anisotropy; nanoscale dynamics; ultrafast spin dynamics; magnetic inertia; nutation; pump-probe; two-temperature model; Fowler-Nordheim tunneling; fysik; Physics;

    Sammanfattning : In this thesis, we studied the ultrafast spin and electron dynamics triggered by electromagnetic radiation belonging to three different regions of the electromagnetic spectrum, namely terahertz, near-infrared and extreme ultraviolet. By performing pump–probe measurements, we explored the role of the lattice in ultrafast spin and electron dynamics in metallic thin films. LÄS MER

  3. 2. Nonlinear pulse propagation and saturation gain grating phenomena in optical fiber devices

    Författare :Evgeny V. Vanin; KTH; []
    Nyckelord :;

    Sammanfattning : Nonlinear effects are known to influence the propagation ofoptical waves in fibers already at modest power levels. Thisprovides us with a unique tool to observe nonlinear phenomenaunder comparatively simple experimental conditions and alsoopens the door to numerous important applications. LÄS MER

  4. 3. Angle-resolved photoemission study of unconventional cuprate superconductors

    Författare :Qinda Guo; Oscar Tjernberg; Andrea Damascelli; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Unconventional superconductivity; cuprate; high harmonic generation; narrow bandwidth light source; spherical grating based monochromator; time- and angle-resolved photoemission spectroscopy; Okonventionell supraledning; kuprat; hög övertonsgenerering; ljuskälla med smal bandbredd; sfäriskt gitterbaserad monokromator; tids- och vinkelupplöst fotoemissionsspektroskopi;

    Sammanfattning : Understanding unconventional superconductivity remains one of the most important unsolved problems in physics. A particularly noteworthy case is the copper-based high-temperature superconductor, which stands out due to its remarkably high transition temperature and relatively simple structure. LÄS MER

  5. 4. Optical studies of carrier transport and fundamental absorption in 4H-SiC and Si

    Författare :Paulius Grivickas; KTH; []
    Nyckelord :;

    Sammanfattning : The Fourier transient grating (FTG) technique and a novelspectroscopic technique, both based on free carrier absorption(FCA) probing, have been applied to study the carrierdiffusivity in 4H-SiC and the fundamental absorption edge in4H-SiC and Si, respectively. FTG is a unique technique capable of detecting diffusioncoefficient dependence over a broad injection interval rangingfrom minority carrier diffusion to the ambipolar case. LÄS MER

  7. 5. Towards ultrafast imaging with extreme ultraviolet light sources

    Författare :Jörg Schwenke; Lunds universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Photo emission electron microscopy; Focusing of X-ray radiation; Digital holography; High-order harmonic generation; Free-electron laser seeding; Secondary electron cascades; Fysicumarkivet A:2012:Schwenke;

    Sammanfattning : This thesis reports experimental studies performed with two advanced coherent XUV sources with ultrashort pulse duration, high-order harmonic generation and seeded-free electron laser. High-order harmonic generation (HHG) is the generation of overtones of a fundamental laser pulse in a medium, e.g. noble gases. LÄS MER