Mechanisms of femtosecond laser ablation of dielectrics revealed by double pump–probe experiment

Mouskeftaras, Alexandros; Guizard, S.; Fedorov, N.; Klimentov, S. M.

doi:10.1007/s00339-012-7217-7

Cited by 56 publications

(33 citation statements)

References 19 publications

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“…The impact ionization, which may lead to electron avalanche, is not introduced here since it is negligible for laser pulse duration shorter than roughly 100 fs [4]. Recent experimental investigations using time-resolved interferometry in fused silica confirm this statement [39]. Our choice not to include impact ionization is also motivated by keeping the simplest reliable modeling to clearly exhibit the role of the MIP on the electron dynamics.…”

Section: Kinetic Equationmentioning

confidence: 99%

Influence of non-collisional laser heating on the electron dynamics in dielectric materials

Barilleau¹,

Duchateau²,

Chimier³

et al. 2016

J. Phys. D: Appl. Phys.

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Abstract. The electron dynamics in dielectric materials induced by intense femtosecond laser pulses is theoretically addressed. The laser driven temporal evolution of the energy distribution of electrons in the conduction band is described by a kinetic Boltzmann equation. In addition to the collisional processes for energy transfer such as electron-phonon-photon and electron-electron interactions, a non-collisional process for photon absorption in the conduction band is included. It relies on direct transitions between sub-bands of the conduction band through multiphoton absorption. This mechanism is shown to significantly contribute to the laser heating of conduction electrons for large enough laser intensities. It also increases the time required for the electron distribution to reach the equilibrium state as described by the Fermi-Dirac statistics. Quantitative results are provided for quartz irradiated by a femtosecond laser pulse with a wavelength of 800 nm and for intensities in the range of tens of TW/cm 2 , lower than the ablation threshold. The change in the energy deposition induced by this non-collisional heating process is expected to have a significant influence on the laser processing of dielectric materials.

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Section: Kinetic Equationmentioning

confidence: 99%

Influence of non-collisional laser heating on the electron dynamics in dielectric materials

Barilleau¹,

Duchateau²,

Chimier³

et al. 2016

J. Phys. D: Appl. Phys.

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“…Additionally, avalanche-ionization can result in an efficient energy deposition [5]. The process, which is mainly responsible for the energy deposition, depends strongly on the laser intensity, thus on the focal volume, pulse energy, pulse duration, and on material properties like the band gap energy [6]- [9]. Manuscript Due to these intensity dependent nonlinear absorption processes the resulting material modifications are limited to the focal volume of the fs-laser radiation.…”

Section: Introductionmentioning

confidence: 99%

Crystalline Waveguide Lasers in the Visible and Near-Infrared Spectral Range

Calmano

Müller

2015

IEEE J. Select. Topics Quantum Electron.

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This paper summarizes our recent results on crystalline waveguides and waveguide lasers fabricated by the femtosecond-laser writing technique. Highly efficient waveguide lasers emitting in the near infrared spectral range based on ytterbium and neodymium doped Y 3 Al 5 O 12 with slope efficiencies above 70% and continuous wave output powers of more than 5 W were demonstrated. Furthermore, pulsed laser operation of passively Q-switched Yb:YAG and Nd:YAG wavequide lasers was achieved by incorporating the saturable absorber Cr 4+ :YAG in a monolithic setup. Based on fs-laser written curved structures in Yb:YAG, efficient curved waveguide lasers could be demonstrated. Also, waveguide lasers in the visible spectral range were investigated. We achieved laser emission in the green, orange, red and deep-red spectral region and could demonstrate output powers of more than 1 W with waveguides based on praseodymium doped materials. Additionally, switchable and dual wavelength operation between the orange and red laser emission was achieved. By utilizing the nonlinear crystal KTiOPO 4 as substrate material for fs-laser inscription, nonlinear waveguides were realized. With these devices, efficient second harmonic generation into the blue and green spectral range was achieved.

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“…However, it seems to make more physical sense to take a criteria on the absorbed energy in the material and it was recently demonstrated that it was indeed more appropriate than the critical density one [28]. The described model in the previous section has the ability to evaluate in space and time the amount of energy absorbed in the material, this energy being in the form of excited electrons.…”

Section: Damage Thresholdmentioning

confidence: 98%

Analysis of laser energy deposition leading to damage and ablation of HfO2 and Nb2O5 single layers submitted to 500 fs pulses at 1030 and 343 nm

et al. 2016

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Laser-induced damage thresholds and morphologies of laser ablated sites on dielectric thin films are studied based on experiments and simulations. The films are single layers of hafnia and niobia deposited on fused silica substrates with a magnetron sputtering technique. Laser experiments are conducted with 500 fs pulses at 1030 and 343 nm, and the irradiated sites are characterized with optical profilometry and scanning electron microscopy. The results, i.e., LIDT and damage morphologies, are compared to simulations of energy deposition in the films based on the single rate equation for electron excitation, taking into account transient optical properties of the films during the pulse. The results suggest that a critical absorbed energy as a damage criterion gives consistent results both with the measured LIDT and the observed damage morphologies at fluences close to the damage threshold. Based on the numerical and experimental results, the determined LIDT evolution with the wavelength is described as nearly constant in the near-infrared region, and as rapidly decreasing with laser wavelength in the visible and near-ultraviolet regions.

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Mechanisms of femtosecond laser ablation of dielectrics revealed by double pump–probe experiment

Cited by 56 publications

References 19 publications

Influence of non-collisional laser heating on the electron dynamics in dielectric materials

Influence of non-collisional laser heating on the electron dynamics in dielectric materials

Crystalline Waveguide Lasers in the Visible and Near-Infrared Spectral Range

Analysis of laser energy deposition leading to damage and ablation of HfO2 and Nb2O5 single layers submitted to 500 fs pulses at 1030 and 343 nm

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