Search for dissertations about: "Terahertz radiation"

Showing result 1 - 5 of 19 swedish dissertations containing the words Terahertz radiation.

  2. 1. Ultrafast spin dynamics at the nanoscale : using coherent X-ray and terahertz radiation

    Author : Nanna Zhou Hagström; Stefano Bonetti; Stefan Eisebitt; Ferran Macià Bros; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; XFEL; small-angle X-ray scattering; X-ray holography; ultrafast magnetism; symmetry-breaking; magnetic domains; terahertz; magnetic field enhancement; metamaterial; time-resolved magneto-optical microscope; Physics; fysik;

    Abstract : The field of ultrafast magnetism is driven by the growing need for faster and more efficient magnetic data storage, which comprises the vast majority of the digital information worldwide. However, after more than two decades of intense research, the understanding of the fundamental physical processes governing the transfer of angular momentum necessary for magnetic switching, is still lacking, partially hampered by the appropriate experimental tools. READ MORE

  4. 2. Photonic terahertz-wave generation, radiation and quasioptical integration

    Author : Biddut Kumar Banik; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; semiconductor device modelling; semiconductor diodes; III-V semiconductors; Catadioptric lens; imaging; dipole antennas; slot antennas; lens antennas; semiconductor heterojunctions; dielectric loaded antennas; optical mixers; photomixers; near-field imaging; computer aided engineering; indium compounds; millimetre wave imaging; near-field optics; submillimeter wave generation; photodiodes; terahertz sources; millimetre wave generation; submillimetre wave integrated circuits; microwave imaging; uni-travelling-carrier photodiodes;

    Abstract : This thesis deals with the uni-travelling-carrier photodiode (UTC-PD) based photonic generation of terahertz waves, antenna designs for the terahertz radiation and a novelcatadioptric lens for quasioptical integration.The ongoing and accomplished research work on the UTC-PD, its limitations and optimisation scopes for attaining higher bandwidth and higher output power have been discussed. READ MORE

  5. 3. Terahertz radiation as a pump and probe for studying low frequency vibrations in proteins

    Author : Ida Lundholm; Göteborgs universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Terahertz radiation; Protein dynamics;

    Abstract : Many functionally important structural changes in proteins proceed along the direction of their lowest frequency vibrations. These vibrations correspond to picosecond collective dynamics. Establishing the fundamental relationship between these vibrations and protein function remains a challenge within biophysics. READ MORE

  6. 4. Terahertz spin dynamics in metallic thin film ferromagnets

    Author : Kumar Neeraj; Stefano Bonetti; Andreas Rydh; Michael Farle; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Terahertz; ultrafast magnetism; spin dynamics; spin nutation; magnetization switching; fysik; Physics;

    Abstract : The past two decades have witnessed an increasing interest in understanding and controlling materials at the pico- and femtosecond time scales, the so-called ultrafast regime. Among the broad field of condensed matter physics, magnetism and magnetic materials have attracted much interest both from a fundamental and an applied perspective. READ MORE

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

    Author : Vivek Unikandanunni; Stefano Bonetti; Andreas Rydh; Jurgen Lindner; Stockholms universitet; []
    Keywords : 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;

    Abstract : 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. READ MORE