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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.


Papers
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Journal ArticleDOI
TL;DR: In this paper, it was shown that a single 50-fs laser pulse couples efficiently to a ferromagnetic film during its own propagation, indicating that the material polarization induced by the photon field interacts coherently with the spins.
Abstract: The quest for ultrafast magnetic processes has triggered a new field of research—femtomagnetism: using femtosecond laser pulses to demagnetize ferromagnetic metallic thin films. Despite being the subject of intense research for over a decade, the underlying mechanisms that govern the demagnetization remain unclear. Here, we investigate how an ultrashort laser pulse couples to the spin of electrons in ferromagnetic metals. It is shown that a single 50-fs laser pulse couples efficiently to a ferromagnetic film during its own propagation. This result indicates that the material polarization induced by the photon field interacts coherently with the spins. The corresponding mechanism has its origin in relativistic quantum electrodynamics, beyond the spin–orbit interaction involving the ionic potential. In addition, this coherent interaction is clearly distinguished from the incoherent ultrafast demagnetization associated with the thermalization of the spins. We forecast that the corresponding coherent self-induced processes are the dawn of a new era for future research in magnetism. Femtosecond laser pulses can demagnetize ferromagnetic metallic thin films on an ultrafast timescale. Studying how a single optical pulse interacts with a magnetic film now provides a better understanding of this so-called femtomagnetism.

486 citations

Journal ArticleDOI
TL;DR: In this paper, a 128-element liquid crystal modulator is used to manipulate the phases of optical frequency components which are spatially dispersed within a grating-and-lens pulse shaping apparatus.
Abstract: Programmable shaping of femtosecond pulses by using a 128-element liquid crystal modulator to manipulate the phases of optical frequency components which are spatially dispersed within a grating-and-lens pulse shaping apparatus is described. This apparatus makes possible gray-level control of the spectral phases and allows modification of the pulse shape on a millisecond time scale under electronic control. Refinements in the design of the multielement modulator result in pulse shaping fidelity comparable to that which can be achieved with microlithographically fabricated masks. Several examples of pulse shaping operation, including pulse position modulation, programmable pulse compression, and adjustable cubic phase distortion, are described. >

485 citations

Journal ArticleDOI
TL;DR: In this article, a two-pulse sequence of femtosecond duration phase-locked optical laser pulses is used to resonantly excite vibronic transitions of a molecule, where a definite optical phase angle between the pulses is maintained while varying the interpulse delay with interferometric precision.
Abstract: We introduce a novel spectroscopic technique which utilizes a two‐pulse sequence of femtosecond duration phase‐locked optical laser pulses to resonantly excite vibronic transitions of a molecule. In contrast with other ultrafast pump–probe methods, in this experiment a definite optical phase angle between the pulses is maintained while varying the interpulse delay with interferometric precision. For the cases of in‐phase, in‐quadrature, and out‐of‐phase pulse pairs, respectively, the optical delay is controlled to positions that are integer, integer plus one quarter, and integer plus one half multiples of the wavelength of a selected Fourier component. In analogy with a double slit optical interference experiment, the two the two pulse experiments reported herein involve the preparation and quantum interference of two nuclear wave packet amplitudes state of a molecule.These experiments are designed to be sensitive to the total phase evolution of the wave packet prepared by the initial pulse. The direct de...

484 citations

Journal ArticleDOI
19 Jan 2001-Science
TL;DR: This direct imaging of reactions was achieved using the third-generation apparatus equipped with an electron pulse, a charge-coupled device camera, and a mass spectrometer to demonstrate the vastly improved sensitivity, resolution, and versatility of UED for studying ultrafast structural dynamics in complex molecular systems.
Abstract: Ultrafast electron diffraction (UED) has been developed to study transient structures in complex chemical reactions initiated with femtosecond laser pulses. This direct imaging of reactions was achieved using our third-generation apparatus equipped with an electron pulse (1.07 ± 0.27 picoseconds) source, a charge-coupled device camera, and a mass spectrometer. Two prototypical gas-phase reactions were studied: the nonconcerted elimination reaction of a haloethane, wherein the structure of the intermediate was determined, and the ring opening of a cyclic hydrocarbon containing no heavy atoms. These results demonstrate the vastly improved sensitivity, resolution, and versatility of UED for studying ultrafast structural dynamics in complex molecular systems.

484 citations

Journal ArticleDOI
TL;DR: In this article, a novel technique was developed with which waveguides can be directly written into various optical bulk materials using femtosecond laser pulses, which allows for the realization of a variety of innovative concepts which are not feasible using other fabrication methods.
Abstract: Over the last few years arrays of evanescently coupled waveguides have been brought into focus as a particular representation of functionalized optical materials, in which the dispersion and diffraction of propagating light can be specifically tuned Moreover, it turns out that the light evolution in these systems shares fundamental similarities to the quantum evolution of particle wavefunctions, so that waveguide arrays can act as a model system for emulating quantum mechanics Recently, a novel technique was developed with which waveguides can be directly 'written' into various optical bulk materials using femtosecond laser pulses, which allows for the realization of a variety of innovative concepts which are not feasible using other fabrication methods The aim of this tutorial is to give an introduction to this topic

482 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,403
20223,116
20211,239
20201,571
20191,715
20181,651