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 Micropatterning on Biodegradable Nanofiber Scaffolds by Femtosecond Laser Ablation Process

2016 ◽  
Vol 49 (6) ◽  
pp. 555-559
Author(s):  
Yongwoo Chung ◽  
Indong Jun ◽  
Yu-Chan Kim ◽  
Hyun-Kwang Seok ◽  
Seok Chung ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Femtosecond Laser Ablation ◽  
Ablation Process ◽  
Laser Ablation Process ◽  
Nanofiber Scaffolds

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.

The Influence of DOS Effects on Ablation Properties in High Energy Femtosecond Laser Ablation Process

2011 ◽  
Vol 689 ◽  
pp. 11-15 ◽  
Author(s):  
Hui Li Wei ◽  
Feng Mao ◽  
Xin Yu Tan ◽  
Xiang Ping Huang ◽  
Zhao Wang ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Femtosecond Laser Ablation ◽  
High Energy ◽  
Gold Target ◽  
Laser Ablation Process ◽  
Electron Phonon Coupling ◽  
Melting Threshold ◽  
Electronic Heat ◽  
The Relationship

The numerical simulation of high-energy femtosecond laser ablation on metal target is studied in this paper. Based on the two-temperature model (TTM), a new model considering the effects of the electron density of states (DOS) on electronic heat capacity, electron-phonon coupling coefficient and electronic thermal conductivity is established. As an example of gold target, the relationship between the melting threshold and the thickness of gold films is numerically calculated. Our result is more consistent with the experimental datum in contrast to the results without considering the DOS effects. This shows that the revised TTM of high-energy femtosecond laser ablation (i.e. DOS-TTM) is more reasonable compared with general used TTM.

Femtosecond Laser Ablation of Zr55Al10Ni5Cu30 Bulk Metallic Glass

2007 ◽  
Vol 539-543 ◽  
pp. 1951-1954 ◽  
Author(s):  
Tomokazu Sano ◽  
Kengo Takahashi ◽  
Akio Hirose ◽  
Kojiro F. Kobayashi
Keyword(s):  
Laser Ablation ◽  
Metallic Glass ◽  
Femtosecond Laser ◽  
Bulk Metallic Glass ◽  
Pulse Energy ◽  
Femtosecond Laser Ablation ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Ablation Depth ◽  
Polished Surface

Dependence of the femtosecond laser ablation depth on the laser pulse energy was investigated for Zr55Al10Ni5Cu30 bulk metallic glass. Investigation of the femtosecond laser ablation of bulk metallic glasses has not been reported. Femtosecond laser pulses (wavelength of 800 nm, pulse width of 100 fs, pulse energies of 2 – 900 μJ) were focused and irradiated on the polished surface of metals in air. The ablation depth of the metallic glass is deeper than that of its crystallized metal at a pulse energy in the strong ablation region. We suggest that the energy loss at grain boundaries of hot electrons which is accelerated by the laser electric field influence the ablation depth in the strong ablation region.

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.

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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