scholarly journals Throughput Improvement in Femtosecond Laser Ablation of Nickel by Double Pulses

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6355
Author(s):  
Kunpeng Chu ◽  
Baoshan Guo ◽  
Lan Jiang ◽  
Yanhong Hua ◽  
Shuai Gao ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Delay Time ◽  
Femtosecond Laser Ablation ◽  
Experimental Results ◽  
Energy Ratio ◽  
Ablation Efficiency ◽  
Pulse Delay ◽  
Throughput Improvement ◽  
Energy Ratios ◽  
Simulation Results

In this study, femtosecond laser double pulses were tested to improve their nickel ablation efficiency. The experimental results indicated that compared with single pulses, double pulses with different delay times generated craters with larger diameters and depths. The results obtained for three sets of double pulses with different energy ratios indicated that double pulses with an energy ratio of 1:9 had the highest ablation efficiency, followed by those with energy ratios of 2:8 and 5:5. The double pulses with the aforementioned three energy ratios achieved the maximum ablation efficiency when the delay time was 3–4 ps. Compared with single pulses, double pulses with an energy ratio of 1:9 generated craters with an up to 34% greater depth and up to 14% larger diameter. In addition, an interference effect was observed with a double pulse delay time of 0 ps, which has seldom been reported in the literature. The double pulses were simulated using the two-temperature model. The simulation results indicated that double pulses with an energy ratio of 1:9 with a delay time of 4 ps can perform the strongest ablation. These simulation results are in line with the experimental results.

scholarly journals Study of the formation of 3-D titania nanofibrous structure by MHz femtosecond laser in ambient air

2021 ◽  
Author(s):  
Amirhossein Tavangar ◽  
Bo Tan ◽  
Krishnan Venkatakrishnan
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Deposition Rate ◽  
Femtosecond Laser Ablation ◽  
Ambient Air ◽  
Experimental Results ◽  
Laser Parameters ◽  
Nanofibrous Structure ◽  
Titania Nanostructures ◽  
Multiple Pulses

In this study, we describe the formation mechanism of web-like three-dimensional (3-D) titania nanofibrous structures during femtosecond laser ablation of titanium (Ti) targets in the presence of background air. First, we demonstrate the mechanism of ablation of Ti targets by multiple femtosecond laser pulses at ambient air in an explicit analytical form. The formulas for evaporation rates and the number of ablated particles, which is analogous to the deposition rate of the synthesized nanofibers, for the ablation by a single pulse and multiple pulses as a function of laser parameters, background gas, and material properties are predicted and compared to experimental results. Afterwards, the formation of nanofibrous structures is demonstrated by applying an existing simplified kinetic model to Ti targets and ambient conditions. The predicted theory provides nanofiber diameter dependency with the combination of laser parameters, target properties, and ambient gas characteristics. Experimental studies are then performed on titania nanofibrous structures synthesized by laser ablation of Ti targets using MHz repletion-rate femtosecond laser at ambient air. The models' predictions are then compared with the experimental results, where nanostructures with different morphologies are manufactured by altering laser parameters. Our results indicate that femtosecond laser ablation of Ti targets at air background yields crystalline titania nanostructures. The formation of crystalline titania nanostructures is preceded b thermal mechanism of nucleation and growth. The results point out that laser pulse repetition and dwell time can control the density, size, and pore size of the engineered nanofibrous structure. As the deposition rate of nanostructures is analogous to the ablation rate of the target, higher density of nanofibrous structure is seen at greater laser fluences. The predicted theory can be applied to predict ablation mechanism and nanofiber formation of different materials.

Ablation Dynamics of Silicon by Femtosecond Laser and the Role of Early Plasma

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
X. Zhao ◽  
Y. C. Shin
Keyword(s):  
Femtosecond Laser ◽  
Laser Fluence ◽  
Energy Transport ◽  
Femtosecond Laser Ablation ◽  
Heat Diffusion ◽  
Photon Absorption ◽  
Ablation Efficiency ◽  
Two Photon Absorption ◽  
Laser Fluences ◽  
Plasma Absorption

In this paper, the femtosecond laser ablation of silicon is investigated by a two-dimensional hydrodynamic model. The ablation depth of the silicon wafer ablated in air at different laser intensities is calculated, and the corresponding experimental measurements are carried out for validation. Two different ablation regimes have been identified by varying the laser fluence. While two-photon absorption dominates in the low fluence regime (<2 J/cm2), electron heat diffusion is a major energy transport mechanism at higher laser fluences (>2 J/cm2). The ablation efficiency first increases with the laser fluence, and reaches the peak value at the laser fluence around 8 J/cm2. It starts to drop when the laser fluence further increases, because of the early plasma absorption of the laser beam energy.

scholarly journals Green Wavelength Femtosecond Laser Ablated Copper Surface

2021 ◽  
Author(s):  
Yi-Hsien Liu ◽  
Chung-Wei Cheng
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Nonlinear Absorption ◽  
Femtosecond Laser Ablation ◽  
Electron Transition ◽  
Copper Surface ◽  
Ablation Depth ◽  
Experimental Results ◽  
Transition Effect ◽  
Laser Ablation Process

Abstract During green wavelength femtosecond laser ablation, d-band electrons are excited to become free and to participate in the absorption process. The increased electron temperature also induces the density of state shift and causes the gap between the d-band and the Fermi level to expand. The d-band electron transition effect during the laser ablation process causes nonlinear absorption, therefore, it should always be considered during simulations of laser-copper interaction.This study used a single femtosecond laser pulse with a wavelength of 515 nm and a pulse duration of 300 fs to ablate copper with fluence 0.7 - 63 J/cm2. The experimental results were compared with the theoretical results, where a modified Drude-critical point model was adopted to simulate the ablation depth. The modified model considered the electron transition effect and a two-temperature model that assumed both the linear and nonlinear absorption effect. Comparison of the experimental and simulated results revealed that the simulated ablation depth obtained using the nonlinear absorption model was consistent with the experimental results.

scholarly journals Pulse-Propagation Modeling and Experiment for Femtosecond-Laser Writing of Waveguide in Nd:YAG

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 434 ◽  
Author(s):  
Tao Feng ◽  
Pankaj K. Sahoo ◽  
Francisco R. Arteaga-Sierra ◽  
Christophe Dorrer ◽  
Jie Qiao
Keyword(s):  
Femtosecond Laser ◽  
Experimental Validation ◽  
Pulse Propagation ◽  
Experimental Results ◽  
Propagation Loss ◽  
Type Ii ◽  
Input Energy ◽  
Propagation Equation ◽  
Propagation Modeling ◽  
Simulation Results

In this work, unidirectional pulse propagation equation (UPPE) modeling is performed to study the nonlinear laser-mater interaction in silicon and Nd:Y3Al5O12 (Nd:YAG) crystals. The simulation results are validated with reported experimental results for silicon and applied to Nd:YAG crystals with experimental validation. Stress-induced waveguides are written in Nd:YAG crystals using 515 nm, 300 fs pulses at a 1 kHz repetition rate. Waveguides having a mean propagation loss of 0.21 ± 0.06 dB/cm are obtained, which is lower than the previous reported values for Type-II waveguides written in Nd:YAG crystals. The modeling and experimental results consistently show that the modification (waveguide track) depth increases with input energy. A detailed analysis is presented to control the modal properties of the waveguide in the context of UPPE simulation.

Surface Processing: An Elegant Way to Enhance the Femtosecond Laser Ablation Rate and Ablation Efficiency on Human Teeth

2019 ◽  
Vol 51 (9) ◽  
pp. 797-807 ◽  
Author(s):  
Sarathkumar Loganathan ◽  
Soundarapandian Santhanakrishnan ◽  
Ravi Bathe ◽  
Muthukumaraswamy Arunachalam
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Femtosecond Laser Ablation ◽  
Ablation Rate ◽  
Surface Processing ◽  
Human Teeth ◽  
Ablation Efficiency

scholarly journals Near-Infrared Femtosecond Laser Ablation of Au-Coated Ni: Effect of Organic Fluids and Water on Crater Morphology, Ablation Efficiency and Hydrodynamic Properties of NiAu Nanoparticles

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5544
Author(s):  
Niusha Lasemi ◽  
Günther Rupprechter ◽  
Gerhard Liedl ◽  
Dominik Eder
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Near Infrared ◽  
Defect Formation ◽  
Fatigue Cracks ◽  
Residual Effect ◽  
Femtosecond Laser Ablation ◽  
Laser Target ◽  
Ablation Efficiency ◽  
Crater Morphology

Scanning electron microscopy (SEM) and profilometry of the crater morphology and ablation efficiency upon femtosecond laser ablation of Au-coated Ni targets in various fluids revealed a pronounced dependence on the ablation medium. For ethanol, a sufficient ablation efficiency was obtained, whereas for 2-butanol a higher efficiency indicated stronger laser–target interaction. Hierarchical features in the crater periphery pointed to asymmetrical energy deposition or a residual effect of the Coulomb-explosion-initiating ablation. Significant beam deviation in 2-butanol caused maximum multiple scattering at the crater bottom. The highest values of microstrain and increased grain size, obtained from Williamson–Hall plots, indicated the superposition of mechanical stress, defect formation and propagation of fatigue cracks in the crater circumference. For n-hexane, deposition of frozen droplets in the outer crater region suggested a femtosecond-laser-induced phase explosion. A maximum ablation depth occurred in water, likely due to its high cooling efficiency. Grazing incidence micro X-ray diffraction (GIXRD) of the used target showed residual carbon and partial surface oxidation. The produced nanoparticle colloids were examined by multiangle dynamic light scattering (DLS), employing larger scattering angles for higher sensitivity toward smaller nanoparticles. The smallest nanoparticles were obtained in 2-butanol and ethanol. In n-hexane, floating carbon flakes originated from femtosecond-laser-induced solvent decomposition.

scholarly journals Nonlinear enhancement of femtosecond laser ablation efficiency by hybridization with nanosecond laser

2006 ◽  
Vol 14 (20) ◽  
pp. 9544 ◽  
Author(s):  
J. S. Yahng ◽  
B. H. Chon ◽  
C. H. Kim ◽  
S. C. Jeoung ◽  
H. R. Kim
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Femtosecond Laser Ablation ◽  
Nanosecond Laser ◽  
Ablation Efficiency

Femtosecond laser ablation of dentin and enamel: relationship between laser fluence and ablation efficiency

2015 ◽  
Vol 20 (2) ◽  
pp. 028004 ◽  
Author(s):  
Hu Chen ◽  
Jing Liu ◽  
Hong Li ◽  
Wenqi Ge ◽  
Yuchun Sun ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Laser Fluence ◽  
Femtosecond Laser Ablation ◽  
Ablation Efficiency

scholarly journals Study of the formation of 3-D titania nanofibrous structure by MHz femtosecond laser in ambient air

2021 ◽  
Author(s):  
Amirhossein Tavangar ◽  
Bo Tan ◽  
Krishnan Venkatakrishnan
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Deposition Rate ◽  
Femtosecond Laser Ablation ◽  
Ambient Air ◽  
Experimental Results ◽  
Laser Parameters ◽  
Nanofibrous Structure ◽  
Titania Nanostructures ◽  
Multiple Pulses

In this study, we describe the formation mechanism of web-like three-dimensional (3-D) titania nanofibrous structures during femtosecond laser ablation of titanium (Ti) targets in the presence of background air. First, we demonstrate the mechanism of ablation of Ti targets by multiple femtosecond laser pulses at ambient air in an explicit analytical form. The formulas for evaporation rates and the number of ablated particles, which is analogous to the deposition rate of the synthesized nanofibers, for the ablation by a single pulse and multiple pulses as a function of laser parameters, background gas, and material properties are predicted and compared to experimental results. Afterwards, the formation of nanofibrous structures is demonstrated by applying an existing simplified kinetic model to Ti targets and ambient conditions. The predicted theory provides nanofiber diameter dependency with the combination of laser parameters, target properties, and ambient gas characteristics. Experimental studies are then performed on titania nanofibrous structures synthesized by laser ablation of Ti targets using MHz repletion-rate femtosecond laser at ambient air. The models' predictions are then compared with the experimental results, where nanostructures with different morphologies are manufactured by altering laser parameters. Our results indicate that femtosecond laser ablation of Ti targets at air background yields crystalline titania nanostructures. The formation of crystalline titania nanostructures is preceded b thermal mechanism of nucleation and growth. The results point out that laser pulse repetition and dwell time can control the density, size, and pore size of the engineered nanofibrous structure. As the deposition rate of nanostructures is analogous to the ablation rate of the target, higher density of nanofibrous structure is seen at greater laser fluences. The predicted theory can be applied to predict ablation mechanism and nanofiber formation of different materials.

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