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, the interaction of intense, ultra-short laser pulses (USLP) with a surface of transparent dielectrics is considered, and the combination of multi-photon absorption and impact ionization generates a plasma layer at the dielectric boundary.
Abstract: The interaction of intense, ultra-short laser pulses (USLP) with a surface of transparent dielectrics is considered. The combination of multi-photon absorption and impact ionization generates a plasma layer at the dielectric boundary. Interaction with the plasma self-consistently determines the amount of reflected, transmitted and absorbed light, and the spatial distribution of electron density. In the present paper, we model the interaction of USLP with transparent dielectrics. We calculate the evolution of electron density profiles and the variation of reflection, transmission and absorption of laser radiation during the pulse. We show that the laser-created surface plasma acts as a filter transmitting only the leading edge of the laser pulse. The transmitted energy is approximately fixed, nearly independent of input pulse energy. The transmitted energy increases with pulse duration. This increased energy is manifested in the formation of cylindrical shock waves directly applicable to recent experiments investigating absorption and shock generation in water.
73 citations
TL;DR: In this article, the specific behavior of a pulsed magnetron discharge was analyzed and the time development of pulsed discharge was composed of three regimes of operation: (1) plasma buildup, (2) stationary plasma, and (3) decaying plasma when the pulse power is off.
Abstract: This article analyzes a pulsed magnetron discharge. Main attention is devoted to the specific behavior of the pulsed discharge. The time development of pulsed discharge is composed of three regimes of operation: (1) plasma buildup, (2) stationary plasma, and (3) decaying plasma when the pulse power is off. The duration of individual regimes strongly depends on the pulse length t1, the repetition frequency fr of pulses, the power delivered into the discharge, and the operating pressure. The proportion of duration of the regime of plasma buildup to the regime of stationary plasma in the pulse dramatically influences the I–V characteristics of the pulsed discharge and the deposition rate of sputtered films. The I–V characteristics of an unbalanced round planar magnetron with a Cu target 100 mm in diameter are shown. The deposition rate of Cu films sputtered with the pulsed magnetron is also given.
73 citations
TL;DR: In this article, a simple expression for the photon helicity and polarization-flip probabilities in arbitrary background fields, in the low-energy regime, was derived, and the impact of pulse shape and collision geometry on the probabilities and on ellipticity signals of vacuum birefringence.
Abstract: We derive a simple expression for the photon helicity and polarization-flip probabilities in arbitrary background fields, in the low-energy regime. Taking the background to model a focused laser beam, we study the impact of pulse shape and collision geometry on the probabilities and on ellipticity signals of vacuum birefringence. We find that models which do not account for pulse duration can overestimate all signals in near head-on collisions by up to an order of magnitude. Taking pulse duration into account, the flip probability becomes relatively insensitive to both angular incidence and the fine details of the pulse structure.
73 citations
TL;DR: The role of both laser pulse length and duty cycle in controlling the grain size and crystallographic texture of diode laser-deposited Waspaloy powder is investigated in this article.
73 citations
TL;DR: In this article, the propagation of ultra-short laser pulses in air under the influence of diffraction, group velocity dispersion, Kerr nonlinearity, stimulated Raman scattering, ionization, and plasma wakefield excitation is analyzed.
Abstract: Recent theoretical, computational, and experimental work carried out at the Naval Research Laboratory on the propagation of ultra-short laser pulses in air is presented. Fully time-dependent, three-dimensional, nonlinear equations describing the propagation of laser pulses in air under the influence of diffraction, group velocity dispersion,Kerr nonlinearity, stimulated Raman scattering,ionization, and plasma wakefield excitation are presented and analyzed. The propagation code, HELCAP [P. Sprangle, J. R. Penano, and B. Hafizi, Phys. Rev. E 66, 046418 (2002)], is used to simulate the propagation of laser pulses in air under the influence of the physical processes mentioned above. Simulations of laser filamentation together with experimental measurements are used to confirm that the filamentation process is dependent on pulse duration. An equilibrium configuration for optical and plasma filaments in air is derived and the dynamic guiding and spectral broadening of a laser pulse is modeled. The effect of atmospheric turbulence on nonlinear self-focusing is demonstrated. Simulations of a recent electromagnetic pulse (EMP) generation experiment are also presented and the efficiency of EMP generation is determined and found to be extremely small.
73 citations