GHz burst mode femtosecond laser pulses can create distinctive two-dimensional periodic floor nanostructures

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GHz burst mode femtosecond laser pulses can create unique two-dimensional (2D) periodic surface nanostructures
It is well-known that irradiation of linearly polarized femtosecond laser pulses (single-pulse mode) creates one-dimensional (1D) laser-induced periodic floor constructions (LIPSS) whose route is perpendicular to the laser polarization route. Curiously, GHz burst mode femtosecond laser pulses can create distinctive 2D LIPSS that are composed of periodic floor constructions each parallel and perpendicular to the laser polarization route. The power of the GHz burst mode enabling the fabrication of 2D LIPSS will diversify micro and nanostructuring to attain extremely functionalized materials surfaces. Credit score: Shota Kawabata, Shi Bai, Kotaro Obata, Godai Miyaji and Koji Sugioka.

Scientists engaged on laser utility on the RIKEN Heart for Superior Photonics (RAP) have demonstrated that GHz burst mode femtosecond laser pulses can create distinctive two-dimensional (2D) laser-induced periodic floor constructions (LIPSS) on silicon substrates.


Beforehand, the workforce led by the researchers from the Superior Laser Processing Analysis Workforce has reported that the GHz burst mode pulses consisting of a collection of trains of ultrashort laser pulses with a interval of a number of hundred picoseconds (ps) tremendously enhance the ablation effectivity and high quality as in contrast with the standard femtosecond laser processing (single-pulse mode).

Revealed in Worldwide Journal of Excessive manufacturing (IJEM), the workforce utilized the GHz burst mode to manufacture LIPSS on silicon substrates to indicate the power of GHz burst for formation of distinctive nanostructures. They’ve demonstrated that the GHz burst mode femtosecond laser pulses create distinctive 2D LIPSS, that’s distinct from the 1D constructions fabricated by the standard single-pulse mode of linearly polarized femtosecond laser.

Along with 1D LIPSS fabricated by the single-pulse mode, whose route is perpendicular to the laser polarization, one other periodic constructions parallel to the polarization route are fashioned to create a lattice-like sample by the GHz bust mode. Achievements of this research have proven that the GHz burst mode femtosecond laser processing affords distinguished benefits for not solely ablation of supplies but in addition different sorts of processing similar to LIPSS formation, which opens a brand new avenue for micro and nanofabrication.

The workforce has additional proposed a doable mechanism for the formation of 2D LIPSS fashioned by the GHz burst mode, which is considered the synergetic contribution of the electromagnetic and hydrodynamic mechanisms. Particularly, the technology of hotspots with extremely enhanced electrical fields by the localized floor plasmon resonance of subsequent pulses within the bursts throughout the nanogrooves of 1D LIPSS fashioned by the previous pulses creates 2D LIPSS.

Moreover, hydrodynamic instability together with convection stream determines the ultimate construction of 2D LIPSS. Based mostly on this speculation, they efficiently created well-defined 2D LIPSS by tailoring the envelope of the GHz burst.

Formation of LIPSS is a widely known phenomenon, which is realized on various stable surfaces by merely irradiating the fabric surfaces with a number of pulses of linearly polarized laser beam even within the air. Importantly LIPSS can functionalize the fabric surfaces to attain floor coloring, discount of friction, management of floor wettability, and so forth., which is attracting appreciable curiosity in industrial purposes.

The power of the GHz burst mode enabling the fabrication of 2D LIPSS will supply the potential for the formation of extra functionalized surfaces and thereby diversify the applying and speed up the commercialization.

Corresponding creator, Prof. Koji Sugioka, mentioned that “The outcomes that the GHz burst mode femtosecond laser pulses can improve the ablation effectivity with improved ablation high quality, reported by Ilday’s group in 2016, have overturned widespread sense and considerably impacted the group of laser supplies processing. Instantly after that, some teams together with our group began to hold out experiments on GHz burst mode ablation of several types of supplies for extra detailed investigation.”

“Within the means of the GHz burst mode ablation research, we thought-about that extra managed vitality deposition as in contrast with the single-pulse mode may supply some benefits to different kinds of supplies processing. Then, we utilized the GHz burst mode to LIPSS formation and succeeded in exhibiting fascinating outcomes.”

“The obtained outcomes might supply a brand new risk of GHz burst mode for processing aside from ablation, together with microbonding, crystallization, sharpening, two-photon polymerization, and inner optical waveguide writing. Thus, we imagine that GHz burst mode will open new paths to femtosecond laser processing.”

One of many co-authors, Prof. Godai Miyaji, mentioned that “Ultrashort pulse laser subtractive manufacturing is induced by three dominant phenomena of nonlinear optical absorption inside the fabric, vitality switch similar to electron-electron scattering and electron-lattice scattering, and phonon excitation, and ablation. Right here, the relief time of the excited state of the fabric is in a area of femtosecond to sub-microsecond. The traditional single-pulse mode induces ablation by the interplay course of between pulse and static materials, whereas the GHz burst mode interacts with excited materials in leisure.”

“It’s anticipated to induce not solely environment friendly and explicit optical absorption by transiently altering in its but in addition the electromagnetic mechanical interactions beneath high-pressure and high-temperature circumstances. This can be a distinctive bodily course of that can’t be realized and managed by the standard single-pulse mode and is predicted to open up new fields in science and expertise, together with the belief of novel shapes and the creation of latest supplies by way of novel bonding structural adjustments.”

Extra data:
Shota Kawabata et al, Two-dimensional laser-induced periodic floor constructions fashioned on crystalline silicon by GHz burst mode femtosecond laser pulses, Worldwide Journal of Excessive Manufacturing (2023). DOI: 10.1088/2631-7990/acb133

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Worldwide Journal of Excessive Manufacturing

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GHz burst mode femtosecond laser pulses can create distinctive two-dimensional periodic floor nanostructures (2023, January 24)
retrieved 25 January 2023
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