Role of intraband transitions in photocarrier generation

Sato, Shunsuke A.; Lucchini, Matteo; Volkov, Mikhail; Schlaepfer, Fabian; Gallmann, L.; Keller, U.; Rubio, Ángel

doi:10.1103/physrevb.98.035202

Cited by 34 publications

(22 citation statements)

References 56 publications

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“…For higher intensities, the perturbative conditions do not longer stand, leading to a departure of the power-law behavior as observed in Refs. [26,44]. Forhω 0 = 0.6 eV, the behavior of Z is different, where in particular a power law with a large exponent is not observed.…”

Section: A Photoionizationmentioning

confidence: 93%

“…For the ionization process, it implies that resonant conditions (band gap is a multiple of the photon energy) should be used for which main electron transitions take place in the center of the Brillouin zone. Regarding the electron dynamics in the conduction band, the ∇ k term accounts for intraband transitions and can play a role in general [44,45]. However interband transitions is expected to be the main process leading to high-energy electrons able to induce impact ionization, so that only these transitions are considered within the present goal to highlighting the ability of the present OBE to correctly describe the impact ionization.…”

Section: Obe Model Descriptionmentioning

confidence: 99%

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Optical Bloch modeling of femtosecond-laser-induced electron dynamics in dielectrics

et al. 2020

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A model based on optical Bloch equations is developed to describe the interaction of femtosecond laser pulses with dielectric solids, accounting for optical-cycle-resolved electron dynamics. It includes the main physical processes at play: photoionization, impact ionization, direct and collisional laser heating, and recombination. By using an electron band structure, this approach also accounts for material optical properties as nonlinear polarization response. Various studies are performed, shedding light on the contribution of various processes to the full electron dynamics depending on laser intensity and wavelength. In particular, the standard influence of the impact ionization process is retrieved.

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Section: A Photoionizationmentioning

confidence: 93%

Section: Obe Model Descriptionmentioning

confidence: 99%

Optical Bloch modeling of femtosecond-laser-induced electron dynamics in dielectrics

et al. 2020

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“…Besides photoelectron spectroscopy [1][2][3][4], all-optical techniques like attosecond transient absorption spectroscopy (ATAS) [5] have shown their potential for the investigation of fundamental phenomena in semiconductors [6], dielectrics [7], metals [8] and magnetic systems [9], up to petahertz driving fields [10]. The first pioneering experiments brought unprecedented insights in strong-field physics in solid systems, addressing the role of inter-and intra-band excitation from a new perspective [11][12][13]. Nevertheless, the exact interplay between virtual and real electron dynamics on attosecond time scales is far from being completely understood.…”

Section: Introductionmentioning

confidence: 99%

Attosecond timing of the dynamical Franz–Keldysh effect

Lucchini¹,

Sato²,

Schlaepfer³

et al. 2020

J. Phys. Photonics

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To what extent do intra-or inter-band transitions dominate the optical response of dielectrics when pumped by a few-cycle near-infrared transient electric field? In order to find an answer to this question we investigate the dynamical Franz-Keldysh effect in polycrystalline diamond and discuss in detail the attosecond delay of the induced electron dynamics with regard to the driving transient electric field while the peak intensity is varied between 1 × 10 12 and 10×10 12 W cm −2 . We found that the main oscillating feature in transient absorption at 43 eV is in phase with the electric field of the pump, to within 49 ±78 as. However, the phase delay shows a slightly asymmetric V-shaped linear energy dispersion with a rate of about 200 as eV -1 . Theoretical calculations within the dipole approximation reproduce the data and allow us to conclude that intra-band motion dominates under our experimental conditions.

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“…Well-developed applications such as ultrafast laser materials processing 16 and direct laser writing 17 may also have advantages in switching from visible and near-IR to mid-IR. A promising way for controlling the energy deposition inside transparent dielectric materials is to use a two-color ultrafast excitation 18 – 24 . In this scheme a long wavelength heating pulse is more advantageous due to favorable scaling of avalanche ionization (AI) rate and free electron absorption.…”

Section: Introductionmentioning

confidence: 99%

Role of wavelength in photocarrier absorption and plasma formation threshold under excitation of dielectrics by high-intensity laser field tunable from visible to mid-IR

Migal

Mareev

Smetanina

et al. 2020

Sci Rep

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the development of high power mid-iR laser applications requires a study on laser induced damage threshold (LIDT) in the mid-IR. In this paper we have measured the wavelength dependence of the plasma formation threshold (PFT) that is a LIDT precursor. In order to interpret the observed trends numerically, a model describing the laser induced electron dynamics, based on multiple rate equations, has been developed. We show both theoretically and experimentally that PFT at mid-IR wavelengths is controlled by a transition from weak-to strong-field regime of free carrier absorption. in the case of Mgf 2 this transition occurs around 3-4 µ m corresponding to the region of the lowermost PFT. The region of the uppermost PFT is reached around 1 µ m and is governed by an interplay of photoionization and weak-field free carrier absorption which manifests itself in both MgF 2 and Sio 2. The PFT observed in considered materials exhibits a universal dependence on the excitation wavelength in dielectrics. Thus, the presented results pave the route towards efficient and controllable laser-induced material modifications and should be of direct interest to laser researchers and application engineers for prevention of laser-induced damage of optical components in high-intensity mid-IR laser systems. Recent advances in the development of ultra-short laser sources in mid-and far-infrared (IR) regions 1-8 lead to a vast number of new applications. However, a primary technological challenge still relevant for researches is the manufacturing of optical components with high laser-induced damage threshold and desired properties (for instance, high transparency or reflectivity in a wide wavelength range, group delay, etc.). This implies a need for experimental investigation of material damage threshold in the IR spectral region 9,10. Thin-films made of multi-layer stacks of low (fluorides, SiO 2) and high (silicon, germanium) refractive index materials are a key component of high-performance coatings in the mid-IR. Fluorides are also popular host matrices for mid-IR solid-state 11 and fiber lasers 12. The knowledge on damage threshold is also important for a new fascinating mid-IR application of dielectric laser accelerators (DLAs) 13,14. In the mid-IR spectral region, promising materials for on-chip DLA technology are dielectric materials, which have a higher material damage threshold compared to silicon 14,15. Well-developed applications such as ultrafast laser materials processing 16 and direct laser writing 17 may also have advantages in switching from visible and near-IR to mid-IR. A promising way for controlling the energy deposition inside transparent dielectric materials is to use a two-color ultrafast excitation 18-24. In this scheme a long wavelength heating pulse is more advantageous due to favorable scaling of avalanche ionization (AI) rate and free electron absorption. However, a lack of knowledge of the laser-induced damage threshold (LIDT) dependence on the wavelength prevents the optimization of such a concept.

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Role of intraband transitions in photocarrier generation

Cited by 34 publications

References 56 publications

Optical Bloch modeling of femtosecond-laser-induced electron dynamics in dielectrics

Optical Bloch modeling of femtosecond-laser-induced electron dynamics in dielectrics

Attosecond timing of the dynamical Franz–Keldysh effect

Role of wavelength in photocarrier absorption and plasma formation threshold under excitation of dielectrics by high-intensity laser field tunable from visible to mid-IR

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