scholarly journals Femtosecond Laser Pulses: Generation, Measurement and Propagation

2021 ◽  
Author(s):  
Mounir Khelladi
Keyword(s):  
Laser Pulse ◽  
Femtosecond Laser ◽  
Ultrashort Laser Pulse ◽  
Short Pulse ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Light Pulses ◽  
Large Bandwidth ◽  
Temporal Shape ◽  
Ultrashort Laser

In this contribution some basic properties of femtosecond laser pulse are summarized. In sections 2.1–2.5 the generation of femtosecond laser pulses via mode locking is described in simple physical terms. In section 2.6 we deal with measurement of ultrashort laser pulses. The characterization of ultrashort pulses with respect to amplitude and phase is therefore based on optical correlation techniques that make of the short pulse itself. In section 3 we start with the linear properties of ultrashort light pulses. However, due to the large bandwidth, the linear dispersion is responsible for dramatic effects. To describe and manage such dispersion effects a mathematical description of an ultrashort laser pulse is given first before we continue with methods how to change the temporal shape via the frequency domain. The chapter ends with a paragraph of the wavelet representation of an ultrashort laser pulse.

Picosecond Single-Photon and Femtosecond Two-Photon Pulsed Laser Stimulation for IC Characterization and Failure Analysis

2009 ◽  
Author(s):  
V. Pouget ◽  
E. Faraud ◽  
K. Shao ◽  
S. Jonathas ◽  
D. Horain ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Single Photon ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Laser Stimulation ◽  
Two Photon ◽  
Resolution Improvement ◽  
Ultrashort Laser

Abstract This paper presents the use of pulsed laser stimulation with picosecond and femtosecond laser pulses. We first discuss the resolution improvement that can be expected when using ultrashort laser pulses. Two case studies are then presented to illustrate the possibilities of the pulsed laser photoelectric stimulation in picosecond single-photon and femtosecond two-photon modes.

Controlling ablation mechanisms in sapphire by tuning the temporal shape of femtosecond laser pulses

2014 ◽  
Vol 32 (1) ◽  
pp. 150 ◽  
Author(s):  
J. Hernandez-Rueda ◽  
J. Siegel ◽  
M. Galvan-Sosa ◽  
A. Ruiz de la Cruz ◽  
M. Garcia-Lechuga ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Temporal Shape

scholarly journals Towards optimization of femtosecond laser pulse nanostructuring of targets for high-intensity laser experiments in vacuum

2021 ◽  
Vol 127 (7) ◽  
Author(s):  
A. Andreev ◽  
J. Imgrunt ◽  
V. Braun ◽  
I. Dittmar ◽  
U. Teubner
Keyword(s):  
Laser Pulse ◽  
Femtosecond Laser ◽  
High Intensity ◽  
Extreme Ultraviolet ◽  
Theoretical Models ◽  
Laser Pulses ◽  
High Energy ◽  
Femtosecond Laser Pulses ◽  
Laser Development ◽  
Laser Experiments

AbstractThe interaction of intense femtosecond laser pulses with solid targets is a topic that has attracted a large amount of interest in science and applications. For many of the related experiments a large energy deposition or absorption as well as an efficient coupling to extreme ultraviolet (XUV), X-ray photon generation, and/or high energy particles is important. Here, much progress has been made in laser development and in experimental schemes, etc. However, regarding the improvement of the target itself, namely its geometry and surface, only limited improvements have been reported. The present paper investigates the formation of laser-induced periodic surface structures (LIPSS or ripples) on polished thick copper targets by femtosecond Ti:sapphire laser pulses. In particular, the dependence of the ripple period and ripple height has been investigated for different fluences and as a function of the number of laser shots on the same surface position. The experimental results and the formation of ripple mechanisms on metal surfaces in vacuum by femtosecond laser pulses have been analysed and the parameters of the experimentally observed “gratings” interpreted on base of theoretical models. The results have been specifically related to improve high-intensity femtosecond-laser matter interaction experiments with the goal of an enhanced particle emission (photons and high energy electrons and protons, respectively). In those experiments the presently investigated nanostructures could be generated easily in situ by multiple pre-pulses irradiated prior to a subsequent much more intense main laser pulse.

scholarly journals Clean source of soft X-ray radiation formed in supersonic Ar gas jets by high-contrast femtosecond laser pulses of relativistic intensity

2020 ◽  
Vol 8 ◽  
Author(s):  
Maria Alkhimova ◽  
Sergey Ryazantsev ◽  
Igor Skobelev ◽  
Alexey Boldarev ◽  
Jie Feng ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Femtosecond Laser ◽  
Argon Plasma ◽  
Plasma Source ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Average Charge ◽  
High Contrast ◽  
X Ray ◽  
Gas Jets

In this work, we optimized a clean, versatile, compact source of soft X-ray radiation $(E_{\text{x}\text{-}\text{ray}}\sim 3~\text{keV})$ with an yield per shot up to $7\times 10^{11}~\text{photons}/\text{shot}$ in a plasma generated by the interaction of high-contrast femtosecond laser pulses of relativistic intensity $(I_{\text{las}}\sim 10^{18}{-}10^{19}~\text{W}/\text{cm}^{2})$ with supersonic argon gas jets. Using high-resolution X-ray spectroscopy approaches, the dependence of main characteristics (temperature, density and ionization composition) and the emission efficiency of the X-ray source on laser pulse parameters and properties of the gas medium was studied. The optimal conditions, when the X-ray photon yield reached a maximum value, have been found when the argon plasma has an electron temperature of $T_{\text{e}}\sim 185~\text{eV}$ , an electron density of $N_{\text{e}}\sim 7\times 10^{20}~\text{cm}^{-3}$ and an average charge of $Z\sim 14$ . In such a plasma, a coefficient of conversion to soft X-ray radiation with energies $E_{\text{x}\text{-}\text{ray}}\sim 3.1\;(\pm 0.2)~\text{keV}$ reaches $8.57\times 10^{-5}$ , and no processes leading to the acceleration of electrons to MeV energies occur. It was found that the efficiency of the X-ray emission of this plasma source is mainly determined by the focusing geometry. We confirmed experimentally that the angular distribution of the X-ray radiation is isotropic, and its intensity linearly depends on the energy of the laser pulse, which was varied in the range of 50–280 mJ. We also found that the yield of X-ray photons can be notably increased by, for example, choosing the optimal laser pulse duration and the inlet pressure of the gas jet.

Modeling of Surface Manipulation by Femtosecond Laser Pulses

1999 ◽  
Vol 573 ◽  
Author(s):  
A. S. Gruzdeva ◽  
V. E. Gruzdev
Keyword(s):  
Laser Pulse ◽  
Femtosecond Laser ◽  
Electromagnetic Waves ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Formation Processes ◽  
Linear And Nonlinear ◽  
Nonlinear Light Scattering ◽  
Fundamental Physical ◽  
Laser Pulse Interaction

ABSTRACTThere are discussed some fundamental physical aspects of surface manipulation by femtosecond laser pulses. Among touched on problems are formation processes of shock electromagnetic waves and surface ripple structures. Proposed theoretical model of femtosecond laser-pulse interaction with matter is illustrated by results of FDTD modeling of linear and nonlinear light scattering by rough surface. Possibility of surface roughness modification and required for that optimal laser-pulse parameters are discussed on the bases of obtained results.

scholarly journals A study of substrate temperature distribution during ultrashort laser ablation of bulk copper

2007 ◽  
Vol 25 (1) ◽  
pp. 155-159 ◽  
Author(s):  
Y.C. LAM ◽  
D.V. TRAN ◽  
H.Y. ZHENG
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Thermal Power ◽  
Femtosecond Laser Ablation ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Laser Materials ◽  
Laser Ablation Process ◽  
Copper Specimen ◽  
Ultrashort Laser

With the aid of an infrared thermograph technique, we directly observed the temperature variation across a bulk copper specimen as it was being ablated by multiple femtosecond laser pulses. Combining the experimental results with simulations, we quantified the deposited thermal power into the copper specimen during the femtosecond laser ablation process. A substantial amount of thermal power (more than 50%) was deposited in the copper specimen, implying that thermal effect can be significant in femtosecond laser materials processing in spite of its ultrashort pulse duration.

High efficient method for calculating the Straton - Chu integral for problems of interaction of laser radiation with materials

2021 ◽  
pp. 42-60
Author(s):  
Владимир Петрович Жуков ◽  
Михаил Петрович Федорук
Keyword(s):  
Laser Pulse ◽  
Efficient Method ◽  
High Efficiency ◽  
Short Pulse ◽  
Main Idea ◽  
Laser Pulses ◽  
Integral Function ◽  
Femtosecond Laser Pulses ◽  
Computational Domain ◽  
High Efficient

Описан высокоэффективный метод вычисления интеграла Стрэттона-Чу для определения электромагнитного поля, создаваемого отражением плоскопараллельного лазерного импульса от параболического зеркала. Рассмотрены импульс с постоянной во времени амплитудой и импульс фемтосекундной длительности, с зависимостью от времени в виде функции Гаусса. Описанный метод актуален для решения задач о взаимодействии сильно сфокусированных лазерных импульсов с веществом The interaction of femtosecond laser pulses with materials is usually modelled within the approach of nonlinear Maxwell equations. The laser pulse in the calculations is initiated by specifying the conditions for the electric field at the boundary of the computational domain, which is located at a distance of 100-200 micron from the focus. The usually used Gaussian distribution for the radius and time in the boundary conditions are not applicable for such pulses. It is necessary to consider a real optic system, or a system, which can be realized. In the presented paper we address the situation in which the laser pulse is created by the reflection of parallel pulse from a parabolic mirror. To determine the field near the focus we use the Stratton-Chu integral (SCI), with fast oscillating sub-integral function. It makes very difficult to calculate SCI. In the presented paper a highly efficient method allows to overcome this difficulty. The main idea is that a change of variables is made in the integral, which, in the case of a short pulse being important for applications, allows calculating the integral over one of the variables once for all times. In addition, for this variable, the integrand is smooth and its calculation does not require large computational resources. The paper investigates the accuracy of calculating the SCI by the proposed method and demonstrates its high efficiency

scholarly journals Fabricating waveguide Bragg gratings (WBGs) in bulk materials using ultrashort laser pulses

Nanophotonics ◽  
2017 ◽  
Vol 6 (5) ◽  
pp. 743-763 ◽  
Author(s):  
Martin Ams ◽  
Peter Dekker ◽  
Simon Gross ◽  
Michael J. Withford
Keyword(s):  
Femtosecond Laser ◽  
Ion Beam ◽  
Laser Pulses ◽  
Bragg Gratings ◽  
Femtosecond Laser Pulses ◽  
Ultrafast Laser ◽  
Ultrashort Laser Pulses ◽  
Clean Room ◽  
Bulk Materials ◽  
Ultrashort Laser

AbstractOptical waveguide Bragg gratings (WBGs) can be created in transparent materials using femtosecond laser pulses. The technique is conducted without the need for lithography, ion-beam fabrication methods, or clean room facilities. This paper reviews the field of ultrafast laser-inscribed WBGs since its inception, with a particular focus on fabrication techniques, WBG characteristics, WBG types, and WBG applications.

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