Case study on the dynamics of ultrafast laser heating and ablation of gold thin films by ultrafast pump-probe reflectometry and ellipsometry

Pflug, Theo; Wang, J.; Olbrich, M.; Frank, Martin M.; Horn, Alexander

doi:10.1007/s00339-018-1550-4

Cited by 20 publications

(21 citation statements)

References 17 publications

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“…Our experiments improve on earlier ellipsometric pump-probe studies which suffered from shortcomings such as changing positions of the probe spot on the sample or stability issues with the femtosecond lasers, or were performed only at single wavelengths (including imaging mode) [35,36,37,38,39,40,41,42,43].…”

mentioning

confidence: 82%

Ultrafast dynamics of hot charge carriers in an oxide semiconductor probed by femtosecond spectroscopic ellipsometry

Richter,

Herrfurth,

Espinoza

et al. 2019

Preprint

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Many linked processes occur concurrently in strongly excited semiconductors, such as interband and intraband absorption, scattering of electrons and holes by the heated lattice, Pauli blocking, bandgap renormalization and the formation of Mahan excitons. In this work, we disentangle their dynamics and contributions to the optical response of a ZnO thin film. Using our unique setup for broadband pump-probe ellipsometry, we directly and unambiguously obtain the real and imaginary part of the transient dielectric function which we compare with first-principles simulations. The interband and excitonic absorption are partially blocked and screened by the photo-excited electron occupation of the conduction band and hole occupation of the valence band. Simultaneously, intra-valence-band transitions occur at sub-picosecond time scales after holes scatter to the edge of the Brillouin zone. Our results pave new ways for the understanding of non-equilibrium charge-carrier dynamics in materials by reliably distinguishing between changes in absorption coefficient and refractive index, thereby separating competing processes. This information will help to overcome the limitations of materials for high-power optical devices that owe their properties from dynamics in the ultrafast regime.

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mentioning

confidence: 82%

Ultrafast dynamics of hot charge carriers in an oxide semiconductor probed by femtosecond spectroscopic ellipsometry

Richter,

Herrfurth,

Espinoza

et al. 2019

Preprint

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show abstract

“…Leggyakrabban a vizsgált minta abszorpciós, illetve reflexiós tulajdonságainak változásaiból következtetnek a lejátszódó folyamatokra, ezek azonban általában csak a vizsgált anyag optikai tulajdonságaiban bekövetkező változásokat adják meg, míg a dielektromos függvény tényleges értékéről nem tudnak információt szolgáltatni. Az elmúlt évekből csak elvétve találunk olyan eredményeket, ahol a spektroszkópiai ellipszometriátamellyel nagy pontossággal lehet meghatározni különböző anyagok komplex dielektromos függvényét -ötvözték a pumpa-próba módszerrel [1][2][3][4].…”

Section: Bevezetésunclassified

Femtoszekundumos pumpa-próba ellipszometria

Csontos

Pápa

Nagyillés

et al. 2021

Kvantumelektronika 2021

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“…The time-resolved complex refractive index of the laser-irradiated surface has been previously reported by a dual-angle reflectometry technique, which was applied to study the optical dynamics of d-band electrons in transition metals near the threshold fluence [13][14][15][16]. To better determine the refractive index without Fresnel equations, a direct measurement of optical properties has been recently proposed by an ultrafast pump-probe method combining ellipsometry with reflectometry [17,18]. Recent self-reflectivity measurements of femtosecond-laser-heated aluminum and tungsten also confirm the importance of the transient density of states for interpreting the experimental data [19].…”

Section: Introductionmentioning

confidence: 99%

Drude-Lorentz Model for Optical Properties of Photoexcited Transition Metals under Electron-Phonon Nonequilibrium

2021

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Evaluating the optical properties of matter under the action of ultrafast light is crucial in modeling laser–surface interaction and interpreting laser processing experiments. We report optimized coefficients for the Drude–Lorentz model describing the permittivity of several transition metals (Cr, W, Ti, Fe, Au, and Ni) under electron–phonon nonequilibrium, with electrons heated up to 30,000 K and the lattice staying cold at 300 K. A Basin-hopping algorithm is used to fit the Drude–Lorentz model to the nonequilibrium permittivity calculated using ab initio methods. The fitting coefficients are provided and can be easily inserted into any calculation requiring the optical response of the metals during ultrafast irradiation. Moreover, our results shed light on the electronic structure modifications and the relative contributions of intraband and interband optical transitions at high electron temperatures corresponding to the laser excitation fluence used for surface nanostructuring.

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Case study on the dynamics of ultrafast laser heating and ablation of gold thin films by ultrafast pump-probe reflectometry and ellipsometry

Cited by 20 publications

References 17 publications

Ultrafast dynamics of hot charge carriers in an oxide semiconductor probed by femtosecond spectroscopic ellipsometry

Ultrafast dynamics of hot charge carriers in an oxide semiconductor probed by femtosecond spectroscopic ellipsometry

Femtoszekundumos pumpa-próba ellipszometria

Drude-Lorentz Model for Optical Properties of Photoexcited Transition Metals under Electron-Phonon Nonequilibrium

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