First-principles study of ultrafast bandgap dynamics in laser-excited $$\alpha$$-quartz

Kachan, Elena; Tsaturyan, А. А.; Stoian, Razvan; Colombier, Jean‐Philippe

doi:10.1140/epjs/s11734-022-00747-8

Cited by 5 publications

(1 citation statement)

References 25 publications

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“…It has been proven that the increase in conduction electrons density during laser excitation can largely reduce the bandgap. [ 32 ] Meanwhile, the short pulse duration and intense peak power can bring in a rapid heating‐cooling process, which can considerably inhibit the crystal nucleus growth and promote vacancies formation. [ 30 ] The introduction of defective energy level can also reduce the bandgap and change the optical properties.…”

Section: Introductionmentioning

confidence: 99%

Highly Stable and Reversible Coloration of Oxide Nanoparticles Film by Ultrafast‐CW Laser Induced Band Engineering

Hu,

Lin,

et al. 2024

Advanced Optical Materials

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Coloration in oxides meets the challenge in achieving high stability and repeatability simultaneously. In this work, reversible coloration of TiO2 nanoparticles (NPs) film is demonstrated by alternate ultrafast (UF) laser and continuous wave (CW) laser irradiation. Under UF laser irradiation, oxygen vacancies are introduced in the TiO2 lattice, which lead to the bandgap reduction (2.73 to 1.50 eV) and surface blackening. The blackened area can achieve high resolution with size down to ≈1.1 µm. This coloration in TiO2 also shows excellent thermal stability that color fading is negligible even after thermal annealing at 700 K for 2 h in air. The generated high temperature by CW irradiation is known to be beneficial for the O2 dissociation on defected TiO2, thus promoting the internal oxygen diffusion to eliminate the vacancies. The energy band structure of TiO2 can be recovered accordingly, and decoloration is achieved. TiO2‐NPs film shows stable microstructures with barely changed optical properties after 12 cycles of coloration–decoloration process. This band engineering‐induced reversible coloration can also be applicable for broad oxides, e.g., ZnO, HfO2, and Ga2O3. Such highly stable and reversible coloration is promising in high‐performance micro/nano‐devices development for color display and optical encryption.

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Section: Introductionmentioning

confidence: 99%

Highly Stable and Reversible Coloration of Oxide Nanoparticles Film by Ultrafast‐CW Laser Induced Band Engineering

Hu,

Lin,

et al. 2024

Advanced Optical Materials

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

Tsaturyan,

Kachan,

Stoian

et al. 2024

Advanced Physics Research

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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.

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Carrier transport after ultrashort-pulse laser excitation in dielectric materials leads to 10MVm−1 electric fields: Transient birefringence and emission of terahertz radiation

Møller,

Sneftrup,

Julsgaard

et al. 2024

Phys. Rev. B

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First-principles study of ultrafast bandgap dynamics in laser-excited $$\alpha$$-quartz

Cited by 5 publications

References 25 publications

Highly Stable and Reversible Coloration of Oxide Nanoparticles Film by Ultrafast‐CW Laser Induced Band Engineering

Highly Stable and Reversible Coloration of Oxide Nanoparticles Film by Ultrafast‐CW Laser Induced Band Engineering

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

Carrier transport after ultrashort-pulse laser excitation in dielectric materials leads to 10MVm−1 electric fields: Transient birefringence and emission of terahertz radiation

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