scholarly journals Femtosecond Laser-Induced Thermal Transport in Silicon with Liquid Cooling Bath

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2043 ◽  
Author(s):  
Zhe Kan ◽  
Qinghua Zhu ◽  
Haizhou Ren ◽  
Mengyan Shen
Keyword(s):  
Femtosecond Laser ◽  
Solid Surface ◽  
Thermal Transport ◽  
Silicon Surface ◽  
Capillary Wave ◽  
Single Pulse ◽  
Capillary Waves ◽  
Molten Silicon ◽  
Liquid Cooling ◽  
Multiple Pulses

Nanostructured regular patterns on silicon surface are made by using femtosecond laser irradiations. This is a novel method that can modify the surface morphology of any large material in an easy, fast, and low-cost way. We irradiate a solid surface with a 400-nm double frequency beam from an 800-nm femtosecond laser, while the solid surface is submerged in a liquid or exposed in air. From the study of multiple-pulses and single-pulse irradiations on silicon, we find the morphologies of nanospikes and capillary waves to follow the same distribution and periodicity. Thermal transport near the solid surface plays an important role in the formation of patterns; a simulation was done to fully understand the mechanism of the pattern formation in single pulse irradiation. The theoretical models include a femtosecond laser pulse function, a two-temperature model (2-T model), and an estimation of interface thermal coupling. The evolution of lattice temperature over time will be calculated first without liquid cooling and then with liquid cooling, which has not been well considered in previous theoretical papers. The lifetime of the capillary wave is found to be longer than the solidification time of the molten silicon only when water cooling is introduced. This allows the capillary wave to be frozen and leaves interesting concentric rings on the silicon surface. The regular nanospikes generated on the silicon surface result from the overlapping capillary waves.

SURFACE DAMAGE OF CRYSTALLINE SILICON BY LOW FLUENCE FEMTOSECOND LASER PULSES

2004 ◽  
Vol 11 (02) ◽  
pp. 217-221 ◽  
Author(s):  
Y. C. LAM ◽  
D. V. TRAN ◽  
H. Y. ZHENG ◽  
V. M. MURUKESHAN ◽  
J. C. CHAI ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Atmospheric Pressure ◽  
Silicon Surface ◽  
Crystalline Silicon ◽  
Surface Damage ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Lower Number ◽  
Circularly Polarized ◽  
Multiple Pulses

Crystalline silicon kept at atmospheric pressure was irradiated with 775 nm multiple laser pulses of 150 fs duration at repetition rate 250 Hz. The laser pulses were circularly polarized, with a peak laser fluence of 0.03 J/cm2. We observed surface damage at a much lower fluence and lower number of pulses compared to that reported in the literature. Surface damage, cracks and pits formation were observed. The evolution of the surface damage as a function of the number of laser pulses was recorded. The observations were in contrast to the findings in the literature that the silicon surface became structured when irradiated by multiple pulses.

Fabrication and Characterization of Si Nano-Columns by Femtosecond Laser

2012 ◽  
Vol 16 ◽  
pp. 15-20 ◽  
Author(s):  
Omid Tayefeh Ghalehbeygi ◽  
Vural Kara ◽  
Levent Trabzon ◽  
Selcuk Akturk ◽  
Huseyin Kizil
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Laser Beam ◽  
Chemical Etching ◽  
Silicon Surface ◽  
Laser Pulses ◽  
Laser Beam Profile ◽  
Fs Laser ◽  
Fabrication And Characterization

We fabricated Si Nano-columns by a femtosecond laser with various wavelengths and process parameters, whilst the specimen was submerged in water. The experiments were carried out by three types of wavelengths i.e. 1030 nm, 515nm, 343nm, with 500 fs laser pulses. The scales of these spikes are much smaller than micro spikes that are constructed by laser irradiation of silicon surface in vacuum or gases like SF6, Cl2. The Si nano-columns of 300 nm or less in width were characterized by SEM measurements. The formation of these Si Nano-columns that were revealed by SEM observation, indicates chemical etching with laser ablation occurred when surface exposed by laser beam. We observed 200 nm spikes height at the center of laser beam profile and the ones uniform in height at lateral incident area.

Diffraction on a Microbubble and the Morphology of the Silicon Surface Irradiated through Glycerol by a Pair of Femtosecond Laser Pulses

JETP Letters ◽  
2021 ◽  
Vol 113 (2) ◽  
pp. 75-81
Author(s):  
N. A. Inogamov ◽  
S. A. Romashevskiy ◽  
A. I. Ignatov ◽  
V. V. Zhakhovsky ◽  
V. A. Khokhlov ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Silicon Surface ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses

Third harmonic generation on silicon surface induced by femtosecond laser

2019 ◽  
Vol 111 ◽  
pp. 255-261 ◽  
Author(s):  
Xiaoming Lin ◽  
Xiaohong Li ◽  
Yanbin Zhang ◽  
Yuxiao Hou ◽  
Xueying Liu ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Harmonic Generation ◽  
Silicon Surface ◽  
Third Harmonic Generation ◽  
Third Harmonic

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.

scholarly journals Titanium surface modification using femtosecond laser with 1013–1015 W/cm2 intensity in vacuum

2012 ◽  
Vol 31 (1) ◽  
pp. 29-36 ◽  
Author(s):  
M. Trtica ◽  
D. Batani ◽  
R. Redaelli ◽  
J. Limpouch ◽  
V. Kmetik ◽  
...  
Keyword(s):  
Surface Modification ◽  
Femtosecond Laser ◽  
Titanium Surface ◽  
Femtosecond Lasers ◽  
Single Pulse ◽  
Surface Structures ◽  
Pulse Regime ◽  
Periodic Surface ◽  
Reduced Intensity ◽  
Surface Changes

AbstractThe response of titanium surface irradiated with high intensity (1013 – 1015 W/cm2) Ti:sapphire laser was studied in vacuum. Most of the reported investigations were conducted with nano- to femtosecond lasers in gas atmospheres while the studies of titanium surface interacting with femtosecond laser in vacuum are scarce. The laser employed in our experiment was operating at 800 nm wavelength and pulse duration of 60 fs in single pulse regime. The observed surface changes and phenomena are (1) creation of craters, (2) formation of periodic surface structures at the reduced intensity, and (3) occurrence of plasma in front the target. Since microstructuring of titanium is very interesting in many areas (industry, medicine), it can be concluded from this study that the reported laser intensities can effectively be applied for micromachining of the titanium surface (increasing the roughness, formation of parallel periodic surface structures etc.).

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