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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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Proceedings Article
02 May 1993
TL;DR: In this article, the possibility of creating and probing a transient nonequilibrium electron population in metals with ultrashort laser pulses has been demonstrated by different groups, including the possibility to create and probe a transient electron population.
Abstract: The possibility of creating and probing a transient nonequilibrium electron population in metals with ultrashort laser pulses has been demonstrated by different groups.1,2 Because of the large electron densities, electron-electron interactions were assumed to be sufficiently fast to instantaneously thermalize the electron gas, although some deviations from Fermi-distribution behavior were observed dose to the Fermi surface.2 Recently, by using a photoemission technique, thermalization times as long as 600 fs were measured in gold films for large changes of the electron temperature (of the order of 400 K).3

193 citations

Journal ArticleDOI
TL;DR: A simple approach for rejecting unwanted scattered light in two types of time-resolved pump-probe measurements, time-domain thermoreflectance (TDTR) and time- Resolved incoherent anti-Stokes Raman scattering (TRIARS).
Abstract: We describe a simple approach for rejecting unwanted scattered light in two types of time-resolved pump-probe measurements, time-domain thermoreflectance (TDTR) and time-resolved incoherent anti-Stokes Raman scattering (TRIARS). Sharp edged optical filters are used to create spectrally distinct pump and probe beams from the broad spectral output of a femtosecond Ti:sapphire laser oscillator. For TDTR, the diffusely scattered pump light is then blocked by a third optical filter. For TRIARS, depolarized scattering created by the pump is shifted in frequency by approximately 250 cm(-1) relative to the polarized scattering created by the probe; therefore, spectral features created by the pump and probe scattering can be easily distinguished.

193 citations

Journal ArticleDOI
C. Winnewisser1, P. Uhd Jepsen1, M. Schall1, V. Schyja1, Hanspeter Helm1 
TL;DR: In this paper, the phase retardation (PR) of an infrared femtosecond probe pulse is measured in LiTaO3, LiNbO3 and ZnTe and compared with theoretical calculations for the PR signal.
Abstract: Freely propagating THz pulses are detected in electro-optic (eo) crystals by monitoring the phase retardation (PR) of an infrared femtosecond probe pulse. This technique permits the determination of the temporal shape of the THz pulse in the subpicosecond time domain. We present measurements in LiTaO3, LiNbO3, and ZnTe and compare their signal performance as eo crystals with theoretical calculations for the PR signal. ZnTe shows the best performance for eo detection.

193 citations

Journal ArticleDOI
TL;DR: In this article, femtosecond table-top laser system was used to convert low-energy photons into antiparticles, namely positrons, and the average intensity of this source of positrons was estimated to be equivalent to 2×108
Abstract: Utilizing a femtosecond table-top laser system, we have succeeded in converting via electron acceleration in a plasma channel, low-energy photons into antiparticles, namely positrons. The average intensity of this source of positrons is estimated to be equivalent to 2×108 Bq and it exhibits a very favorable scaling for higher laser intensities. The advent of positron production utilizing femtosecond laser pulses may be the forerunner to a table-top positron source appropriate for applications in material science, and fundamental physics research like positronium spectroscopy.

193 citations

Journal ArticleDOI
TL;DR: In this article, a femtosecond code-division multiple access (CDMA) communication system test bed operating over optical fiber in the 1.5 /spl mu/m communication band is presented.
Abstract: This paper reports comprehensive experimental results on a femtosecond code-division multiple-access (CDMA) communication system test bed operating over optical fiber in the 1.5 /spl mu/m communication band. Our test bed integrates together several novel subsystems, including low-loss fiber-pigtailed pulse shapers for encoding-decoding, use of dispersion equalizing fibers in dispersion compensated links for femtosecond pulse transmission and also in femtosecond chirped pulse amplification (CPA) erbium doped fiber amplifiers (EDFAs), and high-contrast nonlinear fiber-optic thresholders. The individual subsystems are described, and single-user system level experimental results demonstrating the ability to transmit spectrally encoded femtosecond pulses over a 2.5-km dispersion compensated fiber link followed by decoding and high contrast nonlinear thresholding are presented.

192 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