Pulse duration

About: Pulse duration is a research topic. Over the lifetime, 19429 publications have been published within this topic receiving 286507 citations.

Practical uses of femtosecond laser micro-materials processing

Abstract: We describe several approaches to basic femtosecond machining and materials processing that should lead to practical applications. Included are results on high-throughput deep hole drilling in glasses in ambient air, and precision high-speed micron-scale surface modification of composite materials and chalcogenide glasses. Ablation of soda-lime silicate glass and PbO lead-silicate is studied under three different sets of exposure conditions, for which both the wavelength and pulse duration are varied. Ablation rates are measured below and above the air ionization threshold. The differences observed are explained in terms of self-channeling in the ablated hole. Fabrication of practical devices such as waveguides and gratings is demonstrated in chalcogenide glass.

Gas breakdown initiated by laser radiation interaction with aerosols and solid surfaces

Abstract: The threshold for generation of high‐density plasma caused by the interaction of laser radiation with solids is examined theoretically. The developed semiquantitative model is applicable for predicting the threshold for generating laser‐supported absorption waves, absorbing plasma produced on surfaces with high‐intensity laser radiation, and also for predicting the threshold of aerosol‐induced gas breakdown, commonly referred to as dirty air breakdown. In developing the model, the vapor density generated by laser interaction with the solid is calculated and then the intensity required to cascade ionize the vapor to full ionization is calculated. Analytic expressions are derived for the breakdown intensity which show the parametric dependence of the threshold. Since the vapor density is a function of laser intensity, and characteristics of the solid, different parametric dependence of the threshold on wavelength, pulse length, and particle characteristics is predicted compared to those determined by previous theoretical models of gas breakdown. Comparison of the threshold predicted by the model agree within a factor of 2 of experimental data for a wide range of experimental conditions including laser pulse duration from 10 nsec to cw, particle sizes from 0.1 μ to laser spot sizes of 1 cm, and wavelength scaling of 1.06–10.6 μ wavelength. Based on the good agreement between theoretical predictions and experimental data, the model can be used to predict thresholds for plasma production for a wide variety of atmospheric and solid‐surface conditions.

Effects of self-steepening and self-frequency shifting on short-pulse splitting in dispersive nonlinear media

Abstract: We characterize the propagation of short optical pulses through dispersive media with a cubic self-focusing nonlinear polarization, which incorporates self-steepening and self-frequency shifting. These effects can significantly affect pulse propagation dynamics, both in the normal but especially in the anomalous dispersion regimes. The nature of the dynamics is significantly different in the two regimes.

Direct-field electron acceleration with ultrafast radially polarized laser beams: scaling laws and optimization

Abstract: In the past few years, there has been a growing interest for direct-field electron acceleration with ultra-intense and ultrafast radially polarized laser beams. This particular acceleration scheme offers the possibility of producing highly collimated mono-energetic relativistic attosecond electron pulses from an initial cloud of free electrons that could be produced by ionizing a nanoparticle. In this paper, we describe how electron energy scales with laser power and we explain how the beam waist size and the pulse duration can be optimized for maximal acceleration. The main conclusion of our work is that an electron can effectively reach the high-intensity optical cycles of this particular beam and be optimally accelerated without the necessity of being released by photoionization near the pulse peak.

Effect of Pulse Duration on Quality Characteristics of Blind Hole Drilled in Glass by ECDM

Abstract: Electrochemical discharge machining (ECDM) has proven its usefulness for micro-machining of hard, brittle, and nonconductive materials. Pulse duration is one of the most important process parameters in ECDM. The present article investigates the effect of pulse duration on aspect ratio of glass material machined by ECDM. An effective range of pulse duration was identified experimentally to achieve better control on the quality characteristics. The quality characteristics measured were machining depth, surface damage, aspect ratio, and tool wear. Results reveal that a limited range of pulse duration affects the quality characteristics leading to high aspect ratio. Further, values of process parameters for high aspect ratio of holes were identified. Effect of applied voltage on tool wear was also investigated.