Excitation and relaxation dynamics in dielectrics irradiated by an intense ultrashort laser pulse

Brouwer, Nils; Rethfeld, B.

doi:10.1364/josab.31.000c28

Cited by 23 publications

(21 citation statements)

References 32 publications

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“…The microscopic processes involved have been followed in detail for crystalline solids by solving Boltzmann equations for the electrons and its collision partners [33,[96][97][98] but this kinetic approach is numerically very expensive. Furthermore, the necessary material parameters are not yet known for water.…”

Section: Description Of the Breakdown Dynamicsmentioning

confidence: 99%

“…Momentum transfer collisions entering the Drude model are collisions of electrons with phonons and heavy particles such as neutrals and ions [10,14,33,[96][97][98][99][100][101][102]. Electron-electron collisions cannot contribute to τ coll as both particles have the same effective mass.…”

Section: Description Of the Breakdown Dynamicsmentioning

confidence: 99%

“…Auger recombination describes an energy-conserving interaction between two low-energy electrons and a hole upon which one electron recombines with the whole, and the other is excited onto a higher energy level. Its role for breakdown processes in silicon and SiO 2 has recently been investigated [97,98] and OH produced during ionization (Fig. 3a).…”

Section: Description Of the Breakdown Dynamicsmentioning

confidence: 99%

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Wavelength dependence of femtosecond laser-induced breakdown in water and implications for laser surgery

et al. 2016

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The wavelength dependence of the threshold for femtosecond optical breakdown in water provides information on the interplay of multiphoton, tunneling and avalanche ionization, and is of interest for parameter selection in laser surgery. We measured the bubble threshold from UV to near-IR wavelengths and found a continuous decrease of the irradiance threshold with increasing wavelength λ. Results are compared to the predictions of a numerical model that assumes a bandgap of 9.5 eV and considers the existence of a separate initiation channel via excitation of valence band electrons into a solvated state followed by rapid upconversion into the conduction band. Fits to experimental data yield an electron collision time of ≈ 1 fs, and an estimate for the capacity of the initiation channel. Using that collision time, the breakdown dynamics was explored up to λ = 2 µm. The irradiance threshold first continues to decrease but levels out for wavelengths longer than 1.3 µm. This opens promising perspectives for laser surgery at wavelengths around 1.3 µm and 1.7 µm, which are attractive because of their large penetration depth into scattering tissues.

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Section: Description Of the Breakdown Dynamicsmentioning

confidence: 99%

Section: Description Of the Breakdown Dynamicsmentioning

confidence: 99%

Section: Description Of the Breakdown Dynamicsmentioning

confidence: 99%

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Wavelength dependence of femtosecond laser-induced breakdown in water and implications for laser surgery

et al. 2016

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“…In addition, since TDDFT is very CPU-time consuming, its coupling to the Maxwell's equations to describe the coupled laser pulse propagation and electron dynamics is not conceivable nowadays. Another approach, less cumbersome, is based on the kinetic Boltzmann's equation [4,5,18]. It describes Markovian interactions between electrons, photons, ions, and phonons in the bulk material.…”

Section: Introductionmentioning

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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“…On longer time scales, beyond the pulse duration, in metals, the energy is transferred to the bulk by electron-lattice heating followed by heterogeneous or homogenous melting leading to ablation in the processed region 8 . In semiconductors and dielectrics, a plasma state or non-thermal melting follows the free electron generation and leads to ablation 3,20,21 .…”

Section: Introductionmentioning

confidence: 99%

Single-femtosecond-laser-pulse interaction with mica

Awasthi

Fuerbach

Kane

2020

Applied Surface Science

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Ultrafast, femtosecond laser pulse interaction with dielectric materials has shown them to have significantly higher laser fluence threshold requirements, as compared to metals and semiconductors, for laser material modification, such as laser ablation. Examples of dielectrics are crystalline materials such as quartz and sapphire, and amorphous glasses. The interaction between femtosecond laser pulses, at a wavelength with negligible linear absorption, and a dielectric has been found to be weak, and multiple pulse irradiation is therefore typically used in order to see significant and quantifiable effects. In this study the dielectric is the crystalline, layered, natural mineral muscovite, a mica with formula ( ) ( ) . Muscovite, newly cleaved, is used in a wide range of technological and scientific applications including as an insulating material in electronics and as an ultra-flat and ultra-clean substrate. A single, ~800 nm wavelength, ~6 micron spotsize, ~150 fs laser pulse is found to lead to a systematic range of laser modification topologies, as a function of the fluence of the single laser pulse, including bulk removal of material. The fs laser pulse/material interaction is greater than expected for a standard dielectric at a given fluence. Optical surface profiling and FESEM are used to characterise the topologies. Contrasting the results of the two techniques supports the use of optical surface profiling to characterise the material modification despite its limitations in lateral resolution as compared to FESEM. The interlayer mineral water content of natural muscovite is proposed as the primary reason that mica behaves differently to a standard dielectric when irradiated with a single 800 nm fs laser pulse.

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Excitation and relaxation dynamics in dielectrics irradiated by an intense ultrashort laser pulse

Cited by 23 publications

References 32 publications

Wavelength dependence of femtosecond laser-induced breakdown in water and implications for laser surgery

Wavelength dependence of femtosecond laser-induced breakdown in water and implications for laser surgery

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

Single-femtosecond-laser-pulse interaction with mica

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