Topic
Pulse duration
About: Pulse duration is a research topic. Over the lifetime, 19429 publications have been published within this topic receiving 286507 citations.
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TL;DR: In this paper, photopumped polymer microlaser was demonstrated using microrings and microdisks of various diameters D ranging from 5 to 200 μm, which were characterized by Q of order 5000, low threshold excitation energy of order 100 pJ/pulse for pulse duration ranging from 100 ps to sub-μs.
Abstract: Substantially improved, photopumped polymer lasers are demonstrated using microrings and microdisks of various diameters D ranging from 5 to 200 μm. Various cavity-dependent laser modes were observed, which for D<10 μm were dominated by a single longitudinal mode with linewidth of less than 1 A. These microlasers were also characterized by Q of order 5000, low threshold excitation energy of order 100 pJ/pulse for pulse duration ranging from 100 ps to sub-μs, and an abrupt increase in the emission directionality and polarization degree. Light emitting diodes with cylindrical geometry, fully compatible with these microlasers are also demonstrated.
112 citations
TL;DR: It is shown theoretically that a single acoustic pulse, a few picoseconds long, can reverse magnetization in a magnetostrictive material Terfenol-D, and the switching threshold is determined by the acoustic pulse area, similar to coherent phenomena in optics.
Abstract: It is shown theoretically that a single acoustic pulse, a few picoseconds long, can reverse magnetization in a magnetostrictive material Terfenol-D. Following giant magnetoelastic changes of free energy density, the magnetization vector is ejected from a local in-plane energy minimum and decays into another minimum. For an acoustic pulse duration significantly shorter than magnetization precession period τac≪Tprec, the switching threshold is determined by the acoustic pulse area, i.e., pulse integral in the time domain, similar to coherent phenomena in optics. Simulation results are summarized in a magnetoacoustic switching diagram and discussed in the context of all-optical magnetization switching by circularly polarized light pulses.
112 citations
TL;DR: In this paper, a femtosecond pulse laser ablation (pulse duration 150fs, wavelength 775nm, repetition rate 250 Hz) of sapphire in the ambient air was investigated.
112 citations
Patent•
IBM1
TL;DR: In this paper, a laser drilling control system utilizing photoacoustic feedback is described, which provides an accurate monitoring of the laser drilling of a multilayered printed circuit board thereby allowing uniform drilling through layers of different optical and photo-acoustic properties by both analyzing the feedback signals received, and adjusting optimally the laser parameters for each successive layer.
Abstract: A laser drilling control system utilizing photoacoustic feedback is described. The control system provides an accurate monitoring of the laser drilling of a multilayered printed circuit board thereby allowing uniform drilling through layers of different optical and photoacoustic properties by both analyzing the photoacoustic feedback signals received, and adjusting optimally the laser parameters such as pulse duration, wavelength, energy, pulse repetition rate, and the number of pulses, for each successive layer. The system also provides an end point detection which prevents underdrilling overheating, and overdrilling of underlying layers and associated damages. According to another aspect of this invention, the control system can be used as a sensitive misregistration detector for aligning the laser beam to a selected drill site for subsequent drilling at the selected drill site.
112 citations
TL;DR: In this paper, the IPP RF driven negative hydrogen ion source was chosen as the reference source for the ITER NBI system due to, in principle, its maintenance free operation and the progress in the RF source development.
Abstract: For heating and current drive the neutral beam injection (NBI) system for ITER requires a 1 MeV deuterium beam for up to 1 h pulse length. In order to inject the required 17 MW the large area source (1.9 m × 0.9 m) has to deliver 40 A of negative ion current at the specified source pressure of 0.3 Pa. In 2007, the IPP RF driven negative hydrogen ion source was chosen by the ITER board as the new reference source for the ITER NBI system due to, in principle, its maintenance free operation and the progress in the RF source development. The performance analysis of the IPP RF sources is strongly supported by an extensive diagnostic program and modelling of the source and beam extraction. The control of the plasma chemistry and the processes in the plasma region near the extraction system are the most critical topics for source optimization both for long pulse operation as well as for the source homogeneity. The long pulse stability has been demonstrated at the test facility MANITU which is now operating routinely at stable pulses of up to 10 min with parameters near the ITER requirements. A quite uniform plasma illumination of a large area source (0.8 m × 0.8 m) has been demonstrated at the ion source test facility RADI. The new test facility ELISE presently planned at IPP is being designed for long pulse plasma operation and short pulse, but large-scale extraction from a half-size ITER source which is an important intermediate step towards ITER NBI.
112 citations