Topic
Femtosecond
About: Femtosecond is a research topic. Over the lifetime, 35106 publications have been published within this topic receiving 691405 citations. The topic is also known as: 1 E-15 s & fs.
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TL;DR: This work achieved a first complete identification by explicitly measuring the time-resolved Kerr ellipticity and rotation, as well as its temperature and magnetic field dependence in epitaxially grown Cu/Ni/Cu wedges.
Abstract: Several magnetic and optical processes contribute to the magneto-optical response of nickel thin films after excitation by a femtosecond laser pulse. We achieved a first complete identification by explicitly measuring the time-resolved Kerr ellipticity and rotation, as well as its temperature and magnetic field dependence in epitaxially grown (111) and (001) oriented Cu/Ni/Cu wedges. The first hundreds of femtoseconds the response is dominated by state filling effects. The true demagnetization takes approximately 0.5-1 ps. At the longer (sub-ns) time scales the spins are found to precess in their anisotropy field. Simple and transparent models are introduced to substantiate our interpretation.
459 citations
TL;DR: In this paper, a bare semiconductor wafer was illuminated by femtosecond optical pulses, and electromagnetic waves radiated from the surface and formed collinear diffraction-limited electromagnetic beams in the inward and outward directions.
Abstract: We have generated electromagnetic beams from a variety of semiconductors. When a bare semiconductor wafer was illuminated by femtosecond optical pulses, electromagnetic waves radiate from the surface and form collinear diffraction‐limited electromagnetic beams in the inward and outward directions. The amplitude and phase of the radiated field depend on carrier mobility, the strength and polarity of the static internal field at the semiconductor surface.
457 citations
TL;DR: In this article, a Ti:sapphire laser was used to ablate holes with a diameter of 300 nm and a depth of 52 nm to produce very small features in materials.
457 citations
TL;DR: In this paper, the authors demonstrate the generation of optical vortices with radial or azimuthal polarization using a space variant polarization converter, fabricated by femtosecond laser writing of self-assembled nanostructures in silica glass.
Abstract: We demonstrate the generation of optical vortices with radial or azimuthal polarization using a space variant polarization converter, fabricated by femtosecond laser writing of self-assembled nanostructures in silica glass. Manipulation of the induced form birefringence is achieved by controlling writing parameters, in particular, the polarization azimuth of the writing beam. The fabricated converter allows switching from radial to azimuthal polarization by controlling the handedness of incident circular polarization.
457 citations
TL;DR: In this paper, high-sensitivity femtosecond transient absorption is applied to directly measure the population-depopulation dynamics of the lowest ( $1S$) and the first excited ( $ 1P$) electron states in CdSe nanocrystals (NC's) of different radii with energy separation up to 16 longitudinal optical phonon energies.
Abstract: High-sensitivity femtosecond transient absorption is applied to directly measure the population-depopulation dynamics of the lowest ( $1S$) and the first excited ( $1P$) electron states in CdSe nanocrystals (NC's) of different radii with $1S$--- $1P$ energy separation up to 16 longitudinal optical phonon energies. Instead of the drastic reduction of the energy relaxation rate expected due to a phonon bottleneck, we observe a fast subpicosecond $1P$-to- $1S$ relaxation, with the rate enhanced in NC's of smaller radius. This indicates the opening of new confinement-enhanced relaxation channels which likely involve Auger-type electron-hole energy transfer.
450 citations