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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: A drastic reduction of air resistivity is reported following the passage of a self-guided femtosecond pulse from a Ti:sapphire laser system at 800 nm with energies per pulse between 1 and 14 mJ and a pulse duration of 120 fs.
Abstract: We report a drastic reduction of air resistivity following the passage of a self-guided femtosecond pulse from a Ti:sapphire laser system at 800 nm with energies per pulse between 1 and 14 mJ and a pulse duration of 120 fs. Connected plasma filaments with a length that can exceed 150 cm are created by these pulses. The presence of a conducting plasma channel results from multiphoton ionization of air molecules in the filament core.

134 citations

PatentDOI
TL;DR: In this paper, the authors proposed a method to generate single-cycle THz pulses from a few tens of nanometers thin layer of split ring resonators via optical rectification of femtosecond laser pulses.
Abstract: Provided are systems and methods to generate single-cycle THz pulses from a few tens of nanometers thin layer of split ring resonators (SRRs) via optical rectification of femtosecond laser pulses. The emitted THz radiation, with a spectrum ranging from about 0.1 to 4 THz, arises exclusively from pumping the magnetic-dipole resonance of SRRs around 200 THz. This resonant enhancement, together with pump polarization dependence and power scaling of the THz emission, underpins the nonlinearity from optically induced circulating currents in SRRs, with a huge effective nonlinear susceptibility of 0.8×10−16 m2/V that far exceeds surface nonlinearities of both thin films and bulk organic/inorganic crystals and sheet nonlinearities of non-centrosymmetric materials such as ZnTe.

134 citations

Journal ArticleDOI
TL;DR: Second harmonic generation from AlGaAs nanocylinders of 400 nm height and varying radius pumped with femtosecond pulses delivered at 1554-nm wavelength has been measured, revealing a peak conversion efficiency exceeding 10-5 for nanocyleinders with an optimized geometry.
Abstract: We demonstrate monolithic aluminum gallium arsenide (AlGaAs) optical anoantennas. Using a selective oxidation technique, we fabricate such epitaxial semiconductor nanoparticles on an aluminum oxide substrate. Second harmonic generation from an AlGaAs nanocylinder of height h=400 nm and varying radius pumped with femtosecond pulses delivered at 1554-nm wavelength has been measured, revealing a peak conversion efficiency exceeding 10-5 for nanocylinders with an otpimized geometry.

134 citations

Journal ArticleDOI
TL;DR: Details about the expansion of the blue but also the red side of the continuum due to cross-phase modulation (XPM) and transfer of energy to dispersive waves are revealed and experimentally confirmed.
Abstract: We investigate supercontinuum generation in photonic crystal fibers under femtosecond single and dual wavelength pumping experimentally and by numerical simulations. Details about the expansion of the blue but also the red side of the continuum due to cross-phase modulation (XPM) and transfer of energy to dispersive waves are revealed and experimentally confirmed. Additionally, simple guidelines are given to predicte the maximum bandwidth of supercontinuum generation only by the use of the dispersion curve of the fiber.

134 citations

Journal ArticleDOI
TL;DR: In this paper, a femtosecond differential absorption measurements of the quantum-confined transitions in CdSe microcrystallites are reported, which are consistently explained by bleaching of one-pair states and induced absorption caused by photoexcited two electron-hole pair states.
Abstract: Femtosecond differential absorption measurements of the quantum-confined transitions in CdSe microcrystallites are reported. Spectral hole burning is observed, which is accompanied by an induced absorption feature on the high-energy side. The spectral position of the burned hole depends on the excitation wavelength. For excitation on the low-energy side of the lowest quantum-confined transition, a slight shift of the hole towards the line center is observed. The hole width increases with pump intensity and the magnitude of the induced transparency saturates at the highest excitation level. The results are consistently explained by bleaching of one-pair states and induced absorption caused by the photoexcited two electron-hole pair states. It is concluded that the presence of one electron in the excited state prevents further absorption of photons at the pair-transition energy and accounts for the major portion of the bleaching of the transition. >

134 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