Thermal-induced effects on ultrafast laser filamentation in ethanol
Document Type
Article
Publication Date
8-1-2023
Abstract
Fs laser filamentation in ethanol is studied for bottom-up nanomaterials synthesis at different laser repetition rate. Measurements of energy loss, visible conical images, transmitted beam profile and the optical emission spectra show that laser repetition rate affects ultrafast laser filamentation in ethanol significantly because of the induced thermal processes. Firstly, near the threshold laser energy for self-focusing, high laser repetition rate could interfere with the process, via thermal defocusing that inhibits the onset of filamentation. An enlarged, near flat-top laser beam is produced for the conditions that favor thermal lensing. Secondly, at high laser energy, thermal defocusing effect is saturated as convective heat dissipation occurs. Thus, self-focusing prevailed and led to filamentation at all repetition rates. The strong convection at high laser repetition rate increases the rate of reactions for nanodiamonds synthesis, as the flow of fresh ethanol precursor to the localized filamentation zone is enhanced.
Keywords
Ultrafast laser filamentation, Nanodiamonds, Repetition rate, Critical power, Thermal lensing, Thermo-optic coefficient
Divisions
PHYSICS
Funders
Ministry of Education, Malaysia FRGS/1/2019/STG07/MMU/02/1,Sandisk/Western Digital Malaysia,Penang State Government
Publication Title
Optics and Laser Technology
Volume
163
Publisher
Elsevier Sci Ltd
Publisher Location
THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND