Ultrafast Photon-Electron Interactions in Dielectrics by a Single Laser Pulse

2004 ◽  
Author(s):  
L. Jiang ◽  
H. L. Tsai
Keyword(s):  
Laser Pulse ◽  
Impact Ionization ◽  
Fused Silica ◽  
Ablation Depth ◽  
Ultrafast Laser ◽  
Quantum Mechanical ◽  
Free Electrons ◽  
Electron Generation ◽  
Major Factors ◽  
Crater Shape

This study develops a quantum mechanical model to investigate energy absorption in ultrafast laser of dielectrics. The model investigates the optical property variations, electron temperature, and density changes at femtosecond scales. The ionizations and electron heating are two major factors considered for pulse absorption occurring within the pulse duration. The flux-doubling model is employed to calculate the free electron generation mainly through impact ionization and photoionization. The quantum mechanical treatments are used to account for the specific heat and the relaxation time for free electrons. The time and space dependent optical properties of the dense plasma generated by the ultrafast laser pulse are calculated. The predictions of ablation threshold and ablation depth of fused silica and barium aluminum borosilicate (BBS) are in good agreements with published experimental data. The model greatly improves the accuracy in predicting the ablation depth and can predict the crater shape.

Molecular Dynamics Simulation of Ultrafast Laser Ablation of Fused Silica

2006 ◽  
Author(s):  
Changrui Cheng ◽  
Xianfan Xu ◽  
Yaguo Wang ◽  
Alejandro Strachan
Keyword(s):  
Molecular Dynamics ◽  
Laser Ablation ◽  
Ultrafast Lasers ◽  
Laser Energy ◽  
Laser Pulses ◽  
Fused Silica ◽  
Ultrafast Laser ◽  
Dynamics Simulation ◽  
Free Electrons ◽  
Ultrafast Laser Ablation

In recent decades, ultrafast lasers have been used successfully to micro-machine fused silica. The high intensity laser pulses first excite valence electrons to the conduction band via photoionization and avalanche ionization. The excited free electrons absorb laser energy, and transfer its energy to the ions, resulting in the temperature rise. This ionization leads to significant changes in Coulomb forces among the atoms. Both thermal and non-thermal (Coulomb explosion) ablation processes have been discussed in the literature [1]. This work applies molecular dynamics technique to study the interaction between ultrafast laser pulses and fused silica and the resulting ablation. The main goal of this work is to investigate the ultrafast laser ablation process of fused silica, and to reveal the mechanisms leading to the material's removal. In this MD simulation, the equilibrium state of fused silica is first established at 300 K, and the laser heating and material removal processes are simulated. The ionization of the material and the energy coupling between the laser beam and free electrons and ions are considered. Thermal and non-thermal mechanisms of fused silica ablation are discussed based on calculation results.

Heat Accumulation in Ultrafast Laser Scanning of Fused Silica

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Hong Shen ◽  
Han Wang ◽  
Chenyun Tian
Keyword(s):  
Laser Pulse ◽  
Laser Scanning ◽  
Energy Deposition ◽  
Laser Pulse Energy ◽  
Fused Silica ◽  
Ultrafast Laser ◽  
Heat Accumulation ◽  
Nonthermal Processing ◽  
Electromagnetic Model ◽  
Ionization Model

Abstract In this work, a numerical model to predict the heat accumulation of fused silica induced by ultrafast laser scanning is put forward, which is composed of an ionization model and a steady electromagnetic model. The ionization model is to obtain the energy deposition induced by single laser pulse. Subsequently, the temperature evolution during ultrafast laser scanning is estimated through the superposition of the heat impact by each laser pulse. The ablated profile from experiments is compared with the predicted profile of heat-affected zone (HAZ) to illustrate the nonthermal processing window, which is validated by Raman spectrum. The analysis of the parametric sensitivity on heat accumulation is carried out, and the laser pulse energy is the dominating factor.

Femtosecond laser pulse-train induced breakdown in fused silica: the role of seed electrons

2014 ◽  
Vol 47 (43) ◽  
pp. 435105 ◽  
Author(s):  
Kaihu Zhang ◽  
Lan Jiang ◽  
Xin Li ◽  
Xuesong Shi ◽  
Dong Yu ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Femtosecond Laser ◽  
Femtosecond Laser Pulse ◽  
Pulse Train ◽  
Fused Silica

scholarly journals Electron quantum path control in high harmonic generation via chirp variation of strong laser pulses

2021 ◽  
Author(s):  
Stylianos Petrakis ◽  
Makis Bakarezos ◽  
Michael Tatarakis ◽  
Emmanouil Benis ◽  
Nektarios Papadogiannis
Keyword(s):  
Laser Pulse ◽  
Ultraviolet Light ◽  
Harmonic Generation ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
High Harmonic Generation ◽  
Ultrafast Laser ◽  
Temporal Window ◽  
Electron Quantum ◽  
Extreme Ultraviolet Light

Abstract The quantum phases of the electron paths driven by an ultrafast laser in high harmonic generation in an atomic gas depends linearly on the instantaneous cycle-averaged laser intensity. Using high laser intensities, a complete single ionisation of the atomic gas may occur before the laser pulse peak. Therefore, high harmonic generation could be localized only in a temporal window at the leading edge of laser pulse envelope. Varying the laser frequency chirp of an intense ultrafast laser pulse, the centre, and the width of the temporal window, that the high harmonic generation phenomenon occurs, could be controlled with high accuracy. This way, both the duration and the phase of the electron trajectories, that generate efficiently high harmonics, is fully controlled. An accurate and robust method of spectral control and selection of the high harmonic extreme ultraviolet light from distinct quantum paths is experimentally demonstrated. Furthermore, a phenomenological numerical model enlightens the physical processes that take place. This novel approach of the electron quantum path selection via laser chirp is a simple and versatile way of controlling the time-spectral characteristics of the coherent extreme ultraviolet light with future applications in the fields of attosecond pulses and soft x-ray nano-imaging.

scholarly journals Parametric generation of surface deformations in laser interaction with overdense plasmas

2002 ◽  
Vol 20 (2) ◽  
pp. 337-340 ◽  
Author(s):  
A. MACCHI ◽  
M. BATTAGLINI ◽  
F. CORNOLTI ◽  
T.V. LISSEIKINA ◽  
F. PEGORARO ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Laser Pulse ◽  
Fast Electron ◽  
Analytical Modeling ◽  
Ultrashort Laser Pulse ◽  
Laser Interaction ◽  
Parametric Generation ◽  
Surface Modes ◽  
Electron Generation ◽  
Ultrashort Laser

By analytical modeling and numerical simulation, we show that surface modes in moderately overdense plasmas may be excited parametrically by an intense, ultrashort laser pulse. This process has a feedback effect on fast electron generation and may seed a fast distortion of plasma “moving mirrors.”

Fast and direct optical dispersion estimation for ultrafast laser pulse compression

2021 ◽  
Vol 92 (11) ◽  
pp. 113702
Author(s):  
Jui-Chi Chang ◽  
Shu-Yu Chang ◽  
Yu-Cheng Wu ◽  
Chia-Yuan Chang
Keyword(s):  
Laser Pulse ◽  
Pulse Compression ◽  
Ultrafast Laser ◽  
Optical Dispersion ◽  
Ultrafast Laser Pulse
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