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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, the spectra of Compton radiation emitted during electron scattering off an intense laser beam are calculated using the framework of strong-field quantum electrodynamics, similar to Neville and Rohrlich.
Abstract: The spectra of Compton radiation emitted during electron scattering off an intense laser beam are calculated using the framework of strong-field quantum electrodynamics. We model these intense laser beams as finite length plane-wave-fronted pulses, similar to Neville and Rohrlich [Phys. Rev. D 3, 1692 (1971)], or as trains of such pulses. Expressions for energy and angular distributions of Compton photons are derived such that a comparison of both situations becomes meaningful. Comparing frequency distributions for both an isolated laser pulse and a laser pulse train, we find a very good agreement between the results for long pulse durations which breaks down, however, for ultrashort laser pulses. The dependence of angular distributions of emitted radiation on a pulse duration is also investigated. Pronounced asymmetries of angular distributions are found for very short laser pulses, which gradually disappear with increasing the number of laser field oscillations. Those asymmetries are attributed to asymmetries of the vector potential describing an incident laser beam.

89 citations

Journal ArticleDOI
TL;DR: In this article, a 10-picosecond drive pulse was used to tailor the spectral content for radiography with medium density alloy metals, and the impact of using >1ps pulse duration on laser-accelerated electron beam generation and transport was discussed alongside the optimisation of subsequent Bremsstrahlung emission in thin, high atomic number target foils.
Abstract: Pulsed beams of energetic X-rays and neutrons from intense laser interactions with solid foils are promising for applications where bright, small emission area sources, capable of multi-modal delivery are ideal. Possible end users of laser-driven multi-modal sources are those requiring advanced non-destructive inspection techniques in industry sectors of high value commerce such as aerospace, nuclear and advanced manufacturing. We report on experimental work that demonstrates multi-modal operation of high power laser-solid interactions for neutron and X-ray beam generation. Measurements and Monte-Carlo radiation transport simulations show that neutron yield is increased by a factor ~ 2 when a 1mm copper foil is placed behind a 2mm lithium foil, compared to using a 2cm block of lithium only. We explore X-ray generation with a 10 picosecond drive pulse in order to tailor the spectral content for radiography with medium density alloy metals. The impact of using >1ps pulse duration on laser-accelerated electron beam generation and transport is discussed alongside the optimisation of subsequent Bremsstrahlung emission in thin, high atomic number target foils. X-ray spectra are deconvolved from spectrometer measurements and simulation data generated using the GEANT4 Monte-Carlo code. We also demonstrate the unique capability of laser-driven X-rays in being able to deliver single pulse high spatial resolution projection imaging of thick metallic objects. Active detector radiographic imaging of industrially relevant sample objects with a 10ps drive pulse is presented for the first time, demonstrating that features of 200µm size are resolved when projected at high magnification.

89 citations

Journal ArticleDOI
TL;DR: In this paper, a simple theory for evaluating the several measures used to characterize the intermittency of fine-scale turbulence, and corroborates the theoretical results from comparison with experimental data, some of which are new.
Abstract: This paper presents a simple theory for evaluating the several measures used to characterize the intermittency of fine-scale turbulence, and corroborates the theoretical results from comparison with experimental data, some of which are new. The basic analytical tool is the envelope of the narrow-bandpass-filtered turbulent signal, defined via its Hilbert transform and the analytic signal. The contribution of this paper is twofold. First, it correctly identifies the roles played by the filter characteristics (such as the bandwidth) in determining the intermittency factor, the width of the active regions (pulses) in narrow-bandpass-filtered turbulent signals, and the pulse frequency; it also reveals that all dynamical characteristics of the signal enter indirectly through the peak pulse frequency and the threshold setting. Secondly, the theory suggests that, in the far-dissipation range, the most important feature of signals exhibiting internal intermittency is the stronger-than-algebraic roll-off of the spectral density in that region; it is argued that this feature of turbulence essentially determines the peak pulse frequency in that region. The theory is incomplete in that it does not show how the threshold setting depends on the signal dynamics, but here the discussion is supplemented by experimental data.

89 citations

Journal ArticleDOI
TL;DR: Because the Wise-Witter irradiation method for the treatment of open angle glaucoma depends on low power, thermal mechanisms, this instrument may also be useful for the Treatment of this disease entity.
Abstract: A Q-switched Nd:YAG laser apparatus Manufactured by LASAG AG, CH-3600 Thun has been used in the treatment of a number of pathological conditions of the anterior and posterior segments of the human eye. This laser system may be driven in a free running mode, thereby allowing variation of pulse duration over a range of 12 ns to 10 ms. With increasing pulse duration, non-linear, mechanical damage patterns characteristic of the biological effects at the lower exposure duration range become unimportant when compared to the so-called thermal effects met at the upper pulse duration range. The thermal damage mechanisms may be useful when applied together with the mechanical damage mechanism, for instance when iris perforations are intended. Because the Wise-Witter irradiation method for the treatment of open angle glaucoma depends on low power, thermal mechanisms, this instrument may also be useful for the treatment of this disease entity. This same irradiation mode may also be applied to at least some irradiation tasks of the retina and choroid.

89 citations

Journal ArticleDOI
TL;DR: It is shown that such a MIXSEL can also support pulse repetition rate scaling from ≈5 GHz to >100 GHz with excellent beam quality and high average output power, by mechanically changing the cavity length of the linear straight cavity and the output coupler.
Abstract: The high-power semiconductor laser studied here is a modelocked integrated external-cavity surface emitting laser (MIXSEL), which combines the gain of vertical-external-cavity surface-emitting lasers (VECSELs) with the saturable absorber of a semiconductor saturable absorber mirror (SESAM) in a single semiconductor layer stack. The MIXSEL concept allows for stable and self-starting fundamental passive modelocking in a simple straight cavity and the average power scaling is based on the semiconductor disk laser concept. Previously record-high average output power from an optically pumped MIXSEL was demonstrated, however the long pulse duration of 17 ps prevented higher pulse repetition rates and many interesting applications such as supercontinuum generation and broadband frequency comb generation. With a novel MIXSEL structure, the first femtosecond operation was then demonstrated just recently. Here we show that such a MIXSEL can also support pulse repetition rate scaling from ≈5 GHz to >100 GHz with excellent beam quality and high average output power, by mechanically changing the cavity length of the linear straight cavity and the output coupler. Up to a pulse repetition rate of 15 GHz we obtained average output power >1 W and pulse durations <4 ps. Furthermore we have been able to demonstrate the highest pulse repetition rate from any fundamentally modelocked semiconductor disk laser with 101.2 GHz at an average output power of 127 mW and a pulse duration of 570 fs.

89 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023175
2022408
2021543
2020619
2019668
2018665