scholarly journals Uncertainty Analysis of Melting and Resolidification of Gold Film Irradiated by Nano- to Femtosecond Lasers Using Stochastic Method

2016 ◽  
Author(s):  
Nazia Afrin ◽  
Yuwen Zhang ◽  
J. K. Chen
Keyword(s):  
Femtosecond Laser ◽  
Laser Fluence ◽  
Gold Film ◽  
Control Volume ◽  
Coupling Factor ◽  
Femtosecond Laser Irradiation ◽  
Free Standing ◽  
Input Parameters ◽  
Lattice Coupling ◽  
Solid Liquid

A sample-based stochastic model is presented to investigate the effects of uncertainties of various input parameters, including laser fluence, laser pulse duration, thermal conductivity constants for electron, and electron-lattice coupling factor, on solid-liquid phase change of gold film under nano- to femtosecond laser irradiation. Rapid melting and resolidification of a free standing gold film subject to nano- to femtosecond laser are simulated using a two-temperature model incorporated with the interfacial tracking method. The interfacial velocity and temperature are obtained by solving the energy equation in terms of volumetric enthalpy for control volume. The convergence of variance (COV) is used to characterize the variability of the input parameters, and the interquartile range (IQR) is used to calculate the uncertainty of the output parameters. The IQR analysis shows that the laser fluence and the electron-lattice coupling factor have the strongest influences on the interfacial location, velocity, and temperatures.

scholarly journals Uncertainty Analysis of Melting and Resolidification of Gold Film Irradiated by Nano- to Femtosecond Lasers Using Stochastic Method

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Nazia Afrin ◽  
Yuwen Zhang ◽  
J. K. Chen
Keyword(s):  
Femtosecond Laser ◽  
Laser Fluence ◽  
Gold Film ◽  
Control Volume ◽  
Coupling Factor ◽  
Femtosecond Laser Irradiation ◽  
Free Standing ◽  
Input Parameters ◽  
Lattice Coupling ◽  
Solid Liquid

A sample-based stochastic model is presented to investigate the effects of uncertainties of various input parameters, including laser fluence, laser pulse duration, thermal conductivity constants for electron, and electron–lattice coupling factor, on solid–liquid phase change of gold film under nano- to femtosecond laser irradiation. Rapid melting and resolidification of a free-standing gold film subject to nano- to femtosecond laser are simulated using a two-temperature model incorporated with the interfacial tracking method. The interfacial velocity and temperature are obtained by solving the energy equation in terms of volumetric enthalpy for control volume (CV). The convergence of variance (COV) is used to characterize the variability of the input parameters, and the interquartile range (IQR) is used to calculate the uncertainty of the output parameters. The IQR analysis shows that the laser fluence and the electron–lattice coupling factor have the strongest influences on the interfacial location, velocity, and temperatures.

Periodic Nanostructure on 65Mn Produced by Femtosecond Laser Irradiation

2010 ◽  
Vol 154-155 ◽  
pp. 490-493
Author(s):  
Dong Qing Yuan ◽  
Jian Ting Xu
Keyword(s):  
Femtosecond Laser ◽  
Laser Fluence ◽  
Pulse Length ◽  
Field Vector ◽  
Electric Polarization ◽  
Laser Wavelength ◽  
Femtosecond Laser Irradiation ◽  
Large Area ◽  
Periodic Microstructures ◽  
Processing Control

The periodic microstructures on 65Mn plate were induced by the irradiation of the femtosecond laser with the laser wavelength of 800 nm and the pulse length of 130 fs. The parallel periodic ripples structures were observed at the laser fluence of 1 J/cm2 with different pulses number( N=5,50,400,800) which lied parallel to the laser electric polarization field vector. For 400 pulses, the nano-holes arrays were generated to interrupt the consistent ripples structures.For 800 pulses, initial nano-holes evolution to the grooves, which the direction were uncertainly. Further experiments have been made to induce large area consitent ripple structures by scanning, at the laser fluence of 1 J/cm2 with speed v=500μm/s. 2D arrays were induced by accurate processing control

Ultrafast Laser Induced Subwavelength Periodic Surface Structures on Semiconductors/Metals and Application to SERS Studies

MRS Advances ◽  
2016 ◽  
Vol 1 (49) ◽  
pp. 3317-3327 ◽  
Author(s):  
V. Saikiran ◽  
Mudasir H Dar ◽  
R. Kuladeep ◽  
Narayana Rao Desai
Keyword(s):  
Femtosecond Laser ◽  
Laser Irradiation ◽  
Gold Film ◽  
Low Frequency ◽  
Surface Enhanced Raman Spectroscopy ◽  
Surface Structures ◽  
Femtosecond Laser Irradiation ◽  
Gold Films ◽  
Periodic Surface ◽  
Different Thickness

ABSTRACTIn this manuscript a simple approach is discussed to fabricate uniform periodic surface structures on semiconductor surfaces by femtosecond laser irradiation for surface-enhanced Raman spectroscopy (SERS) applications. Gold films having different thickness are first deposited on semiconductor silicon (Si) surfaces and then periodic surface structures are fabricated by femtosecond laser irradiation. The periodic structures are observed to be uniform over a large area with chain type structure formation of gold and Si. We have studied the formation of these surface structures on Si surface by having different thickness gold films deposited on Si substrates. This approach of the fabrication of surface structures with the assistance of gold film is found to help in local field enhancement and hence work as suitable substrate for the SERS experiments. The conditions for achieving high enhancement factor in SERS with different gold film thicknesses are explored in detail. We also present here the formation of low frequency ripples on Silicon (Si) and high frequency as well as low frequency ripples on titanium (Ti) surface in air and water environments by irradiation with fs laser pulses. Different morphologies were observed on Ti surface depending upon the laser irradiation parameters and the surrounding dielectric medium.

Femtosecond Laser Ablation of Titanium and Silicon

2000 ◽  
Author(s):  
Mengqi Ye ◽  
Costas P. Grigoropoulos
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Laser Fluence ◽  
Laser System ◽  
Femtosecond Laser Ablation ◽  
Laser Pulses ◽  
Femtosecond Laser Irradiation ◽  
Nanosecond Laser ◽  
Iccd Camera ◽  
Plume Emission

Abstract Femtosecond laser ablation of titanium and silicon samples has been studied via time-of-flight (TOF), emission spectroscopy and microscopy measurement. Laser pulses of around 100 fs (FWHM) at λ = 800 nm were delivered by a Ti:sapphire femtosecond laser system. A vacuum chamber with a base pressure of 10−7 torr was built for ion TOF measurement. These ion TOF spectra were utilized to determine the velocity distribution of the ejected ions. While nanosecond laser ablation typically generates ions of a few tens of eV, femtosecond laser irradiation even at moderate energy densities can produce energetic ions with energies of up to a few keV. The most probable energy of these fast ions is proportional to the laser fluence. The structure and number of peaks of the TOF spectra varies with the laser fluence. Images of plume emission were captured by an intensified CCD (ICCD) camera. The plume emission spectrum was analyzed by a spectrometer. Laser ablated craters were measured by an interferometric microscope and a scanning electron microscope (SEM). Ablation yield was expressed as a function of laser fluence, and number of shots.

RIPPLE FORMATION ON InP SURFACE IRRADIATED WITH FEMTOSECOND LASER

2005 ◽  
Vol 04 (04) ◽  
pp. 779-784 ◽  
Author(s):  
H. X. QIAN ◽  
W. ZHOU ◽  
H. Y. ZHENG
Keyword(s):  
Raman Spectroscopy ◽  
Femtosecond Laser ◽  
Laser Irradiation ◽  
Laser Fluence ◽  
Femtosecond Laser Irradiation ◽  
Laser Polarization ◽  
Polarization Direction ◽  
Micro Raman Spectroscopy ◽  
Ripple Formation ◽  
Inp Surface

Single crystalline InP was ablated with linearly p-polarized femtosecond laser in air. Ripples with orientation parallel to the laser polarization direction were formed at low laser fluence. Analyses by EDX reveal In oxides and P oxides on the surface. Micro Raman spectroscopy of the laser irradiated surface indicates presence of stresses and possible formation of InP nanocrystals due to the femtosecond laser irradiation.

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