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Computational Model for Capturing Dynamics of Intense Ultrafast Laser Interaction with Dielectric Materials

Zhang, Simin
http://orcid.org/0000-0001-7494-8230
http://rave.ohiolink.edu/etdc/view?acc_num=osu1689132499015335

Abstract Details

2023, Doctor of Philosophy, Ohio State University, Materials Science and Engineering.
In many scientific and engineering fields, the physical properties of materials can become a vital factor that limits the development of technologies or opens a new pathway to emerging applications. The study of ultrashort laser interaction with solid materials is no different. While the material damage induced by ultra-intense laser pulses has become the principal bottleneck in advances of high power laser technology, the highly localized nature of laser ablation can also expand the toolbox for high-precision material manufacturing. Moreover, few-cycle pulses can make ultrafast optical switching possible, which can be orders of magnitude faster than state-of-the-art electronic switches. In this thesis, with the assist of extensive experiments, a comprehensive computational model is proposed to study the mechanisms of ultrashort laser induced excitation and damage in dielectric materials. First, to capture the dynamic interplay of physical processes during the laser and thin-film material interaction, I wrote a two-dimensional finite difference in time domain (FDTD) multi-physical model incorporating the electromagnetic wave propagation, strong-field Keldysh photoionization theory, impact ionization, Drude-Lorentz model, etc. The simulation results for bulk fused silica and femtosecond laser pulses at varying durations and fluences agree well with the measurements. Then I modeled the laser interactions with multi-layer dielectric (MLD) mirrors and gratings designed for broadband pulses and predicted the laser induced damage thresholds (LIDTs). Next, laser damage experiments and computational modeling were performed to study the laser induced damage in the MLD mirrors and gratings designed for femtosecond laser pulses at 2-micron wavelength. The LIDTs measured by the experiments are consistent with the modeling results. I also observed the blister formation in both gratings and mirrors at fulences below the ablation threshold. The inner structure of the blisters was measured by transmission electron microscopy combined with the focused ion beam. The cross-sectional measurement shows excellent agreement with the FDTD modeling results. It also provides insights into the mechanisms of the thermo-mechanical processes that occur at the lightest stage of laser induced damage. Furthermore, using the FDTD multi-physics model, I also investigated the impact on femtosecond LIDT of MLD gratings caused by surface defects commonly seen in manufacturing and operation, including nodules, cracks, and particle contaminants. In order to study the laser induced damage in silicon resonant nano-antennas with more complex structures, I applied a modified PIC simulation. The hotspot predicted by the modeling coincides with the damage morphology observed in the experiment, which also explains the mechanism of the nanoscale light-driven explosions caused by mid-infrared femtosecond pulses. Finally, I proposed a theoretical and mathematical model that explains the ultrafast optical switching phenomenon in fused silica irradiated by few-cycle pulses below the damage threshold. The model suggests that the transient multi-photon absorption is the source of the reflectance peaks in the visible and near-IR wavelength range under pump excitation; the temporal reflectance oscillation is from the coupling of the material polarization. I also found that the spectral phase of the pump pulse is present in the spectra-temporal reflectance measurement.
Enam Chowdhury (Advisor)
Wolfgang Windl (Committee Member)
Gregory Lafyatis (Other)
Steve Niezgoda (Committee Member)
Roberto Myers (Committee Member)
267 p.
Materials Science; Physics
Laser induced damage; femtosecond lasers; computational models; dielectric materials

Recommended Citations

Citations

  • Zhang, S. (2023). Computational Model for Capturing Dynamics of Intense Ultrafast Laser Interaction with Dielectric Materials [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1689132499015335

    APA Style (7th edition)

  • Zhang, Simin. Computational Model for Capturing Dynamics of Intense Ultrafast Laser Interaction with Dielectric Materials. 2023. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1689132499015335.

    MLA Style (8th edition)

  • Zhang, Simin. "Computational Model for Capturing Dynamics of Intense Ultrafast Laser Interaction with Dielectric Materials." Doctoral dissertation, Ohio State University, 2023. http://rave.ohiolink.edu/etdc/view?acc_num=osu1689132499015335

    Chicago Manual of Style (17th edition)

osu1689132499015335
171
© 2023, some rights reserved.Creative Commons License Computational Model for Capturing Dynamics of Intense Ultrafast Laser Interaction with Dielectric Materials by Simin Zhang is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by The Ohio State University and OhioLINK.