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: In this article, a simple single beam interferometric technique is proposed to characterize the phase singularity of the generated vortex beams, and the experimental results are compared to simulations and a satisfying agreement is obtained.
Abstract: Direct femtosecond laser photopolymerization is used to fabricate high resolution microscopic spiral phase plates. The total phase change all around their center is prepared to be a integer multiple of 2π for the operating wavelength in the visible domain. The optical performances of the spiral plates are measured and we propose a simple single beam interferometric technique to characterize the phase singularity of the generated vortex beams. The experimental results are compared to simulations and a satisfying agreement is obtained. Potential of large scale fabrication, templating, and smart spiral plate architectures are also illustrated.
137 citations
TL;DR: In this paper, the visible and near-UV fluorescence spectroscopy of air generated inside a femtosecond laser plasma filament was studied, and the primary reactions, N 2 + + N 2 ⇒ N 4 + ; N 4+ + e ⇒ n 2 (C 3 Π u ) + n 2, populates the electronic excited state N2(C3Пu) of N2.
137 citations
TL;DR: A mode-locked ytterbium fiber laser that generates femtosecond pulses with energies as large as 2.2 nJ is reported, which represents a 20-fold improvement in pulse energy compared with that of previously reported femTosecond Yb fiber lasers.
Abstract: We report a mode-locked ytterbium fiber laser that generates femtosecond pulses with energies as large as 2.2 nJ. This represents a 20-fold improvement in pulse energy compared with that of previously reported femtosecond Yb fiber lasers. The laser produces pulses as short as 52 fs, which are to our knowledge the shortest pulses to date from a Yb fiber laser. The laser is diode pumped by a wavelength-division multiplexing coupler, which leads to excellent stability.
137 citations
Proceedings Article•
02 May 1993TL;DR: In this article, femtosecond optical spectroscopy was used to observe the vacuum Rabi oscillations associated with the coupled exciton-photon mode splitting in a semiconductor quantum microcavity.
Abstract: We have used femtosecond optical spectroscopy to observe directly the vacuum Rabi oscillations associated with the coupled exciton-photon mode splitting in a semiconductor quantum microcavity. When the microcavity is impulsively excited by a coherent short optical pulse, the time-resolved emission from the cavity shows beats corresponding to the oscillation between cavity and exciton modes, with a decay corresponding to approximately twice the cavity lifetime. Interferometric pump-probe measurements clearly show the coherent evolution of the cavity polarization.
137 citations
TL;DR: In this article, a femtosecond laser microfabrication was used to realize super-hydrophobic patterned polydimethylsiloxane (PDMS) surfaces with tunable adhesion by a femto-conditional laser.
Abstract: We present a rapid, facile, and simple method to realize superhydrophobic patterned polydimethylsiloxane (PDMS) surfaces with tunable adhesion by a femtosecond laser. These surfaces are composed of superhydrophobic laser-induced structures and hydrophobic unstructured square array. The femtosecond laser structured domain shows superhydrophobicity with ultralow water adhesion, while the nonstructured flat PDMS shows ordinary hydrophobicity with ultrahigh water adhesion. By adjusting the relative area fraction of laser structured and nonstructured domains, the as-prepared superhydrophobic surfaces show tunable water adhesion that ranges from ultralow to ultrahigh, on which the sliding angle can be controlled from 1° to 90° (a water droplet cannot slide down even when the as-prepared surface is vertical or turned upside down). The tunable adhesive superhydrophobic surfaces achieved by femtosecond laser microfabrication may be potentially used in microfluidic systems to modulate the mobility of liquid droplets.
137 citations