Electron dynamics in fused silica after strong field laser excitation detected by spectroscopic imaging pump-probe ellipsometry

Pflug, Theo; Olbrich, M.; Horn, Alexander

doi:10.1103/physrevb.106.014307

Cited by 6 publications

(2 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[ 29 ] The spatial, spectral, and temporal properties of the pump and probe radiation in the femtosecond regime were characterized in detail in a previous publication. [ 12 ] During the interaction of the pump radiation with the thin Fe 60 Al 40 and Fe 60 V 40 films, the relative change of reflectance Δ R / R was measured by pump‐probe reflectometry with an angle of incidence of 0° of the probe radiation. The optical beam paths of the pump and probe radiation were changed relatively to each other by a geometrical delay stage, resulting in a temporal range of −0.5 ns < t < 3 ns with a minimum temporal step width of Δ t = 40 fs.…”

Section: Methodsmentioning

confidence: 99%

“…[8][9][10] These alterations to the functional material properties described above can be induced by single-pulsed femtosecond (fs) laser irradiation [9] and can be tracked in the ultrafast time regime by applying pump-probe metrology. [11][12][13][14][15] This approach provides insights into the pathways leading to lattice reordering. However, whereas single fs pulses have been applied to selected systems, the broader scope of the transformations in lattice order remains an open question, for example, the effect of single fs laser pulsing on different types of positional and chemical order and crucially, the time scales at which transformations can be realized.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Laser‐Induced Positional and Chemical Lattice Reordering Generating Ferromagnetism

Pflug,

Pablo‐Navarro,

Anwar

et al. 2023

Adv Funct Materials

Self Cite

View full text Add to dashboard Cite

Atomic scale reordering of lattices can induce local modulations of functional material properties, such as reflectance and ferromagnetism. Pulsed femtosecond laser irradiation enables lattice reordering in the picosecond range. However, the dependence of the phase transitions on the initial lattice order as well as the temporal dynamics of these transitions remain to be understood. This study investigates the laser‐induced atomic reordering and the concomitant onset of ferromagnetism in thin Fe‐based alloy films with vastly differing initial atomic orders. The optical response to single femtosecond laser pulses on selected prototype systems, one that initially possesses positional disorder, Fe60V40, and a second system initially in a chemically ordered state, Fe60Al40, has been tracked with time. Despite the vastly different initial atomic orders the structure in both systems converges to a positionally ordered but chemically disordered state, accompanied by the onset of ferromagnetism. Time‐resolved measurements of the transient reflectance combined with simulations of the electron and phonon temperatures reveal that the reordering processes occur via the formation of a transient molten state with an approximate lifetime of 200 ps. These findings provide insights into the fundamental processes involved in laser‐induced atomic reordering, paving the way for controlling material properties in the picosecond range.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Laser‐Induced Positional and Chemical Lattice Reordering Generating Ferromagnetism

Pflug,

Pablo‐Navarro,

Anwar

et al. 2023

Adv Funct Materials

Self Cite

View full text Add to dashboard Cite

show abstract

Excited‐State Dynamics and Optical Properties of Silica Under Ultrafast Laser Irradiation

Tsaturyan,

Kachan,

Stoian

et al. 2024

Advanced Physics Research

View full text Add to dashboard Cite

Excited by intense infrared ultrafast light pulses, a wide bandgap material undergoes nonlinear ionization, generating a high density of free electrons in conduction states. As a result, the electronic band structure is critically modified and the bandgap shrinks. This induces rapid changes in optical properties, dramatically affecting the absorption spectrum during light coupling to the dielectric surface or during nonlinear propagation inside the bulk. This study analyzes the structural behavior and the modification of the optical properties of laser‐excited silica glass at the molecular cluster level through first‐principles simulations. Employing density functional theory and the GW approximations for band structure under nonequilibrium conditions, alongside the Bethe–Salpeter equation, the dynamics of the optical properties of fused silica are comprehensively explored. The behavior of excited fused silica in a wide photon energy range (from a few to 20 eV) is thus predicted. Laser‐induced electron excitation triggers a redistribution of charges between oxygen and silicon atoms, accompanied by a significant increase in electronic pressure, local atomic structure rearrangement, and material expansion. Molecular dynamics simulations offer a temporal perspective on the excited state dynamics, unveiling the intricate interplay between electronic and atomic effects on bandgap evolution. The analysis sheds light on excitonic resonances, intraband and interband transitions in fused silica under ultrafast laser irradiation, providing valuable insights into its excited state behavior and optical properties.

show abstract

Transient reflectance of silicon carbide during laser-induced phase separation

Pflug,

Bernard,

Jahn

et al. 2024

Appl. Phys. A

View full text Add to dashboard Cite

Laser irradiation can induce local modulations of functional material properties, such as a decreased resistivity or a variation in reflectance. Recent studies investigated the laser-induced phase separation of 4 H-SiC into carbon and silicon on top of regrown SiC to customize its electrical conductivity for the application in electronic devices. To understand the physical processes leading to the laser-induced phase separation, time-resolved pump-probe measurements represent a suitable tool. This study advances the state of the art by characterizing the transient reflectance changes in 4 H-SiC upon irradiation by spatially resolved pump-probe reflectometry. Since the laser heating alters the reflectance of the sample, the spatially resolved measurement enables to observe the heat conduction from the irradiated to the non-irradiated areas, which sustains for several milliseconds. Numerical simulations of the temperature evolution reveal a restricted one-dimensional heat conduction into depth due to the broad lateral extent of the irradiated area. The associated sustained increased temperature within the irradiated area most certainly abets the feasibility of the phase separation. These findings offer practical insights for optimizing the applied laser parameters to tailor the material properties via phase separation.

show abstract

Electron dynamics in fused silica after strong field laser excitation detected by spectroscopic imaging pump-probe ellipsometry

Cited by 6 publications

References 62 publications

Laser‐Induced Positional and Chemical Lattice Reordering Generating Ferromagnetism

Laser‐Induced Positional and Chemical Lattice Reordering Generating Ferromagnetism

Excited‐State Dynamics and Optical Properties of Silica Under Ultrafast Laser Irradiation

Transient reflectance of silicon carbide during laser-induced phase separation

Contact Info

Product

Resources

About