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: Femtosecond fluorescence-upconversion studies of aq.2+ show a short-lived vibrationally hot emission of the singlet metal-to-ligand charge-transfer state, with an ultrafast intersystem crossing to the triplet state at const.
Abstract: Femtosecond fluorescence-upconversion studies of aq. [Ru(bpy)3]2+ show a short-lived vibrationally hot emission of the singlet metal-to-ligand charge-transfer state, with an ultrafast intersystem crossing ( 10 fs) to the triplet state at const. energy (the colors indicate the luminescence intensity). [on SciFinder (R)]
249 citations
TL;DR: In this article, the effects of 810 nm, femtosecond laser radiation on various glasses were investigated by focusing the laser beam via a microscope objective, transparent but visible, round-elliptical damage lines were successfully written inside high silica, borate, soda-lime-silicate, fluoride and chalcogenide glasses.
Abstract: With the goal of creating various optical glass devices for the telecommunications industry, the effects of 810 nm, femtosecond laser radiation on various glasses were investigated. By focusing the laser beam via a microscope objective, transparent but visible, round-elliptical damage lines were successfully written inside high silica, borate, soda-lime-silicate, fluoride and chalcogenide glasses. Microscopic ellipsometric measurements of the damaged region in pure and Ge-doped silica glasses showed refractive index increases of 0.01 to 0.035. The formation of several types of defects, including Si E′ or Ge E′ centers, non-bridging oxygen hole centers, and peroxy radicals, was also detected in addition to the identification. These results suggest that multi-photon interactions occurs in the glasses and that it is possible to write three-dimensional optical circuits in bulk glasses via such a focused laser beam technique.
249 citations
TL;DR: First observation of laser-induced free-free transitions in the primary photoelectron spectra of gaseous helium ionized by ultrashort soft x-ray pulses and the first direct measurements on the temporal duration of femtosecond high order harmonic radiation are reported.
Abstract: We report the first observation of laser-induced free-free transitions in the primary photoelectron spectra of gaseous helium ionized by ultrashort soft x-ray pulses. Measured transition amplitudes are well described by projecting the initial electronic state onto a Volkov wavefunction. Additionally, we report the first direct measurements on the temporal duration of femtosecond high order harmonic radiation. The harmonic pulse duration is observed to exhibit strong dependencies upon both laser intensity and position of the generating medium relative to the laser focus.
249 citations
TL;DR: The observation that carrier heating is ultrafast suggests that energy from absorbed photons can be efficiently transferred to carrier heat and the spectral response is examined and finds a constant spectral responsivity of between 500 and 1,500 nm, consistent with efficient electron heating.
Abstract: Graphene is a promising material for ultrafast and broadband photodetection. Earlier studies have addressed the general operation of graphene-based photothermoelectric devices and the switching speed, which is limited by the charge carrier cooling time, on the order of picoseconds. However, the generation of the photovoltage could occur at a much faster timescale, as it is associated with the carrier heating time. Here, we measure the photovoltage generation time and find it to be faster than 50 fs. As a proof-of-principle application of this ultrafast photodetector, we use graphene to directly measure, electrically, the pulse duration of a sub-50 fs laser pulse. The observation that carrier heating is ultrafast suggests that energy from absorbed photons can be efficiently transferred to carrier heat. To study this, we examine the spectral response and find a constant spectral responsivity of between 500 and 1,500 nm. This is consistent with efficient electron heating. These results are promising for ultrafast femtosecond and broadband photodetector applications.
249 citations
TL;DR: The ability to control both the spectral phase and the spectral polarization enables measurement of a specific off-diagonal susceptibility tensor element while exploiting the different spectral response of the resonant Raman signal and the nonresonant background to achieve maximal background suppression.
Abstract: Phase-and-polarization coherent control is applied to control the nonlinear response of a quantum system We use it to obtain high-resolution background-free single-pulse coherent anti-Stokes Raman spectra The ability to control both the spectral phase and the spectral polarization enables measurement of a specific off-diagonal susceptibility tensor element while exploiting the different spectral response of the resonant Raman signal and the nonresonant background to achieve maximal background suppression
248 citations