Please use this identifier to cite or link to this item: https://hdl.handle.net/10356/146198
Title: Mechanism and effects of surface morphology on absorption characteristics in ultrashort pulse laser processing of sapphire
Authors: Lye, Celescia Siew Mun
Wang, Z. K.
Lam, Yee Cheong
Keywords: Engineering::Mechanical engineering
Issue Date: 2021
Source: Lye, C. S. M., Wang, Z. K., & Lam, Y. C. (2021). Mechanism and effects of surface morphology on absorption characteristics in ultrashort pulse laser processing of sapphire. Applied Surface Science, 542, 148734-. doi:10.1016/j.apsusc.2020.148734
Journal: Applied Surface Science
Abstract: For ultrashort pulse laser processing of a sapphire wafer, nonlinear absorption of laser energy at sufficiently high laser intensity is essential. This study found that in ultrashort pulse laser processing of a sapphire wafer, its surface morphology can have a significant effect on nonlinear absorption and its threshold. Interestingly, for a single side polished wafer, the orientation of the rough or smooth surface towards or away from the laser source (i.e. if the laser is an incident or exit beam) is a critical parameter on the processing outcomes. The orientation of the grinded rough surface affects the amount of light internally reflected within the material; this has a direct impact on the laser energy absorbed and nonlinear absorption threshold. Indeed, the presence of a grinded rough exit surface increases the possibility of total internal reflection of the laser beam at the exit surface; this traps the laser's energy within the material more efficiently and thus promoting nonlinear absorption. This unique characteristic of having total internal reflection at the rough exit surface can result in laser scribing at both the smooth entry and rough exit surfaces simultaneously. This mechanism can be exploited to improve the laser processing of sapphire sample.
URI: https://hdl.handle.net/10356/146198
ISSN: 0169-4332
DOI: 10.1016/j.apsusc.2020.148734
Rights: © 2020 Elsevier B.V. All rights reserved. This paper was published in Applied Surface Science and is made available with permission of Elsevier B.V.
Fulltext Permission: embargo_20230322
Fulltext Availability: With Fulltext
Appears in Collections:MAE Journal Articles

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