Ultrafast laser filamentation in ethanol for nanomaterials synthesis

Ultrafast laser filamentation occurs when laser light propagating in nondiffracting regime, at high laser intensity for distance greater than Rayleigh length in transparent media. An extended high intensity core with clamped intensity, supercontinuum and plasma is generated during laser filamentatio...

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Main Author:	Tan, Han Yi
Format:	Thesis
Published:	2022
Subjects:	QC501-(721) Electricity
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id	my-mmu-ep.12035
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spelling	my-mmu-ep.120352024-01-10T09:29:14Z Ultrafast laser filamentation in ethanol for nanomaterials synthesis 2022-11 Tan, Han Yi QC501-(721) Electricity Ultrafast laser filamentation occurs when laser light propagating in nondiffracting regime, at high laser intensity for distance greater than Rayleigh length in transparent media. An extended high intensity core with clamped intensity, supercontinuum and plasma is generated during laser filamentation. In this work, the characteristics of laser filamentation in ethanol is studied, and the possibilities of nanomaterials synthesis from the generated plasma is explored. In the first part of the work, the dependence of ultrafast laser filamentation on the incident laser energy is studied via measurement of energy loss, side view imaging, forward emission, time integrated optical emission spectroscopy and transmitted beam profiles. The results show that laser filamentation starts at ~110 times of critical power of self-focusing (Pcr). As the laser energy increases (310 Pcr), stronger and multiple filamentation occurred and emission peaks are detected. Finally, at even higher laser energy (750 Pcr), ethanol is vaporised. The characteristics of laser filamentation is discussed and nanomaterials synthesis is performed at the laser energy where multiple filamentation occur below the vaporisation threshold. Nanodiamonds are obtained, as characterised by absorbance measurement, photoluminescence, XPS and HR-TEM. In the second part, the role of laser repetition rate in ultrafast laser filamentation in ethanol is studied; to determine its effect on laser filamentation, and to increase the yield for nanomaterials synthesis. The results indicate that laser repetition rate influence the laser filamentation process through thermal process. At fixed laser energy of 90 µJ (110 times Pcr), laser filamentation occurs only at the repetition rate of <1 kHz. No filamentation is obtained above 1 kHz. Laser filamentation is inhibited due to thermal defocusing. At 400 µJ, laser filamentation is observed for all repetition rates where heat convection occurs and increase the interaction rate. In addition, improved fluid flow in ethanol helps in laser filamentation nanomaterials synthesis. 2022-11 Thesis http://shdl.mmu.edu.my/12035/ http://erep.mmu.edu.my/ masters Multimedia University Faculty of Engineering (FOE) EREP ID: 11739
institution	Multimedia University
collection	MMU Institutional Repository
topic	QC501-(721) Electricity
spellingShingle	QC501-(721) Electricity Tan, Han Yi Ultrafast laser filamentation in ethanol for nanomaterials synthesis
description	Ultrafast laser filamentation occurs when laser light propagating in nondiffracting regime, at high laser intensity for distance greater than Rayleigh length in transparent media. An extended high intensity core with clamped intensity, supercontinuum and plasma is generated during laser filamentation. In this work, the characteristics of laser filamentation in ethanol is studied, and the possibilities of nanomaterials synthesis from the generated plasma is explored. In the first part of the work, the dependence of ultrafast laser filamentation on the incident laser energy is studied via measurement of energy loss, side view imaging, forward emission, time integrated optical emission spectroscopy and transmitted beam profiles. The results show that laser filamentation starts at ~110 times of critical power of self-focusing (Pcr). As the laser energy increases (310 Pcr), stronger and multiple filamentation occurred and emission peaks are detected. Finally, at even higher laser energy (750 Pcr), ethanol is vaporised. The characteristics of laser filamentation is discussed and nanomaterials synthesis is performed at the laser energy where multiple filamentation occur below the vaporisation threshold. Nanodiamonds are obtained, as characterised by absorbance measurement, photoluminescence, XPS and HR-TEM. In the second part, the role of laser repetition rate in ultrafast laser filamentation in ethanol is studied; to determine its effect on laser filamentation, and to increase the yield for nanomaterials synthesis. The results indicate that laser repetition rate influence the laser filamentation process through thermal process. At fixed laser energy of 90 µJ (110 times Pcr), laser filamentation occurs only at the repetition rate of <1 kHz. No filamentation is obtained above 1 kHz. Laser filamentation is inhibited due to thermal defocusing. At 400 µJ, laser filamentation is observed for all repetition rates where heat convection occurs and increase the interaction rate. In addition, improved fluid flow in ethanol helps in laser filamentation nanomaterials synthesis.
format	Thesis
qualification_level	Master's degree
author	Tan, Han Yi
author_facet	Tan, Han Yi
author_sort	Tan, Han Yi
title	Ultrafast laser filamentation in ethanol for nanomaterials synthesis
title_short	Ultrafast laser filamentation in ethanol for nanomaterials synthesis
title_full	Ultrafast laser filamentation in ethanol for nanomaterials synthesis
title_fullStr	Ultrafast laser filamentation in ethanol for nanomaterials synthesis
title_full_unstemmed	Ultrafast laser filamentation in ethanol for nanomaterials synthesis
title_sort	ultrafast laser filamentation in ethanol for nanomaterials synthesis
granting_institution	Multimedia University
granting_department	Faculty of Engineering (FOE)
publishDate	2022
_version_	1794019131827159040

Ultrafast laser filamentation in ethanol for nanomaterials synthesis

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