scholarly journals Enhanced ablation efficiency for silicon by femtosecond laser microprocessing with GHz bursts in MHz bursts (BiBurst)

2021 ◽  
Author(s):  
Francesc Caballero-Lucas ◽  
Kotaro Obata ◽  
Koji Sugioka
Keyword(s):  
Laser Ablation ◽  
Repetition Rate ◽  
High Speed ◽  
Single Pulse ◽  
Pulse Mode ◽  
Heat Diffusion ◽  
Ablation Efficiency ◽  
Mode Laser ◽  
Multiple Pulses ◽  
5 Ghz

Abstract Ultrashort laser pulses confine material processing to the laser-irradiated area by suppressing heat diffusion, resulting in precise ablation in diverse materials. However, challenges occur when high speed material removal and higher ablation efficiencies are required. Ultrafast burst mode laser ablation has been proposed as a successful method to overcome these limitations. Following this approach, we studied the influence of combining GHz bursts in MHz bursts, known as BiBurst mode, on ablation efficiency of silicon. BiBurst mode used in this study consists of multiple bursts happening at a repetition rate of 64 MHz, each of which contains multiple pulses with a repetition rate of 5 GHz. The obtained results show differences between BiBurst mode and conventional single pulse mode laser ablation, with a remarkable increase in ablation efficiency for the BiBurst mode, which under optimal conditions can ablate a volume 4.5 times larger than the single pulse mode ablation when delivering the same total energy in the process.

Laser ablation efficiency during the production of Ag nanoparticles in ethanol at a low pulse repetition rate (1–10 Hz)

2016 ◽  
Vol 13 (10) ◽  
pp. 106002 ◽  
Author(s):  
M A Valverde-Alva ◽  
T García-Fernández ◽  
E Esparza-Alegría ◽  
M Villagrán-Muniz ◽  
C Sánchez-Aké ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Ag Nanoparticles ◽  
Repetition Rate ◽  
Pulse Repetition Rate ◽  
Pulse Repetition ◽  
Ablation Efficiency

scholarly journals Formation of colloidal solutions of silicon nanoparticles in ethyl alcohol with ultra-short laser pulses

2021 ◽  
Vol 66 (1) ◽  
pp. 7-11
Author(s):  
A. P. Laskovnev ◽  
M. I. Markevich ◽  
A. N. Malyshko ◽  
V. I. Zhuravleva ◽  
A. M. Chaplanov
Keyword(s):  
Laser Ablation ◽  
Ethyl Alcohol ◽  
Silicon Nanoparticles ◽  
Yttrium Aluminum Garnet ◽  
Single Pulse ◽  
Laser Pulses ◽  
Pulse Mode ◽  
Time Interval ◽  
Laser Exposure ◽  
Colloidal Solutions

The study of surface morphology of a silicon target after laser exposure, the formation and study of nanoparticles, obtained by laser ablation by ultrashort infrared pulses, were conducted. The material was processed using a yttrium aluminum garnet laser (LS-2134D) with a wavelength of 1064 nm, generating in a two-pulse mode (pulses are separated by a time interval of 3 μs, pulse duration is 10 ns, pulse repetition rate is 10 Hz, single pulse energy ~ 0.05 J). Alcohol solutions of silicon nanoparticles were obtained by laser ablation. It is shown that an ensemble of particles of different sizes (from 20 nm to 2.5 μm) is formed, which have no faceting. Using the method of scanning electron microscopy, the features of the morphology of the surface of the crater of polycrystalline silicon, which is in ethyl alcohol during pulsed laser processing in the double pulse mode, have been established. It is shown that the structure of the crater consists of silicon grains separated from each other by grooves; the material evaporates along the grain boundaries, and wide thermal etching grooves are formed. These results can be used to create solar cells.

scholarly journals Influence of Duty Ratio and Current Mode on Robot 316L Stainless Steel Arc Additive Manufacturing

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 508
Author(s):  
Ping Yao ◽  
Hongyan Lin ◽  
Wei Wu ◽  
Heqing Tang
Keyword(s):  
Stainless Steel ◽  
Additive Manufacturing ◽  
Heat Input ◽  
Low Frequency ◽  
Single Pulse ◽  
Pulse Mode ◽  
Double Pulse ◽  
Duty Ratio ◽  
Utilization Rate ◽  
Specimen Height

Wire and arc additive manufacturing (WAAM) is usually for fabricating components due to its low equipment cost, high material utilization rate and cladding efficiency. However, its applications are limited by the large heat input decided by process parameters. Here, four 50-layer stainless steel parts with double-pulse and single-pulse metal inert gas (MIG) welding modes were deposited, and the effect of different duty ratios and current modes on morphology, microstructure, and performance was analyzed. The results demonstrate that the low frequency of the double-pulse had the effect of stirring the molten pool; therefore, the double-pulse mode parts presented a bigger width and smaller height, finer microstructure and better properties than the single-pulse mode. Furthermore, increasing the duty ratio from 35% to 65% enlarged the heat input, which then decreased the specimen height, increased the width, and decreased the hardness and the tensile strength.

High repetition rate laser ablation for vapor–liquid–solid nanowire growth

2014 ◽  
Vol 14 (4) ◽  
pp. 614-620 ◽  
Author(s):  
A. Marcu ◽  
F. Stokker ◽  
R.R. Zamani ◽  
C.P. Lungu ◽  
C. Grigoriu
Keyword(s):  
Laser Ablation ◽  
Repetition Rate ◽  
High Repetition Rate ◽  
Nanowire Growth ◽  
Vapor Liquid Solid ◽  
High Repetition ◽  
Vapor Liquid

scholarly journals Passive Switched Capacitor RF Front Ends for Spectrum Sensing in Cognitive Radios

2014 ◽  
Vol 2014 ◽  
pp. 1-20
Author(s):  
Bodhisatwa Sadhu ◽  
Martin Sturm ◽  
Brian M. Sadler ◽  
Ramesh Harjani
Keyword(s):  
Spectrum Sensing ◽  
Circuit Design ◽  
Software Defined Radio ◽  
High Speed ◽  
Cognitive Radios ◽  
Optimization Techniques ◽  
Switched Capacitor ◽  
Rf Receiver ◽  
Front End ◽  
5 Ghz

This paper explores passive switched capacitor based RF receiver front ends for spectrum sensing. Wideband spectrum sensors remain the most challenging block in the software defined radio hardware design. The use of passive switched capacitors provides a very low power signal conditioning front end that enables parallel digitization and software control and cognitive capabilities in the digital domain. In this paper, existing architectures are reviewed followed by a discussion of high speed passive switched capacitor designs. A passive analog FFT front end design is presented as an example analog conditioning circuit. Design methodology, modeling, and optimization techniques are outlined. Measurements are presented demonstrating a 5 GHz broadband front end that consumes only 4 mW power.

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