Effect of input pulse chirp on nonlinear energy deposition and plasma excitation in water

Milián, Carles; Jarnac, Amélie; Brelet, Yohann; Jukna, Vytautas; Houard, Aurélien; Mysyrowicz, A.; Couairon, Arnaud

doi:10.1364/josab.31.002829

Cited by 25 publications

(25 citation statements)

References 57 publications

(69 reference statements)

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“…Since multiphoton initiation is the critical hurdle for the occurrence of IR ns breakdown, and E ini is very close to the previously assumed band gap value of 6.5 eV [4,11,13,14,[21][22][23][24][25][26][27], the breakdown threshold will remain almost the same. The larger band gap value will affect mainly the electron and energy density reached at the end of the breakdown process, which are determined by the avalanche ionization rate that is lower for a larger band gap.…”

Section: Conclusion For Breakdown Modeling In Generalsupporting

confidence: 71%

“…Since then, this approach has been adopted by numerous researchers designing models for optical breakdown in water. Most researchers followed Sacchi in using a band gap of 6.5 eV [4,13,14,[22][23][24][25][26][27], while in some recent studies values of 7 eV [28] and 8 eV [29] were employed. However, spectroscopic evidence collected in the past two decades suggests that Sacchi's approach oversimplifies the band structure of water.…”

Section: Introductionmentioning

confidence: 99%

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Wavelength dependence of nanosecond infrared laser-induced breakdown in water: Evidence for multiphoton initiation via an intermediate state

et al. 2015

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Investigation of the wavelength dependence (725 -1025 nm) of the threshold for nanosecond optical breakdown in water revealed steps consistent with breakdown initiation by multiphoton ionization, with an initiation energy of about 6.6 eV. This value is considerably smaller than the autoionization threshold of about 9.5 eV, which can be regarded as band gap relevant for avalanche ionization. Breakdown initiation is likely to occur via excitation of a valence band electron into a solvated state, followed by rapid excitation into the conduction band. Theoretical analysis based on these assumptions suggests that the seed electron density required for initiating avalanche ionization drops from 2.5×10 15 cm -3 at 725 nm to 1.1×10 12 cm -3 at 1025 nm. These results demand changes of future breakdown modeling for water including the use of a larger band gap than previously employed, the introduction of an intermediate energy level for initiation, and consideration of the wavelength dependence of seed electron density.

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Section: Conclusion For Breakdown Modeling In Generalsupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Wavelength dependence of nanosecond infrared laser-induced breakdown in water: Evidence for multiphoton initiation via an intermediate state

et al. 2015

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“…We adopted the electron density (electrons before relaxation stages) as 2×10 19 cm -3 from Milián's analysis. [15] Assuming that 11% of the dry electrons survive as esol -, we estimated the concentration of [esol − ] ~3×10 -3 M. The initial esolcould decrease to half in about 60 ns using the bimolecular rate constant of 5.5×10 9 M -1 s -1 . [35] The reaction between esol − and OH• in (8) would more efficiently quench esol − than that the annihilation (7).…”

Section: Between H• and H2omentioning

confidence: 99%

“…These high electron density states-i.e., weak plasma states-would be generated in a small volume when using focused femtosecond pulses due to water absorption/ionization, accompanied by SC generation. [15,16] To resolve these questions and clarify the underlying mechanisms, a low energy femtosecond laser pulse would be preferable. In this paper, the formation of NPs was observed using pulses in the energy range of micro-Joules, which to our knowledge is the lowest range shown to form NPs, and is the same energy range at which M 3+ reduction occurs accompanied by SC generation.…”

Section: Introductionmentioning

confidence: 99%

Metal ion reductions by femtosecond laser pulses with micro-Joule energy and their efficiencies

Nakashima

Yamanaka

Saeki

et al. 2016

Journal of Photochemistry and Photobiology A: Chemistry

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Chemical reactions of metal ions in solution were studied using 800 nm, 90 femtosecond laser pulses with a laser intensity range beginning at sub-micro-Joules/pulse, where the intensities were at or just below supercontinuum generation. Products were observed as surface resonance absorptions assignable to Ag, Au nanoparticles (NPs) and light scattering, indicating the formation of Pd NPs. The consumption efficiencies of metal ions from the Au and Pd ions were estimated to be 10 -3 per incident photon. The major absorbing species of the laser energy was water, which led to the formation of solvated electrons that acted as a reducing agent of metal ions, while direct multi-photon dissociation to neutral atoms was unlikely. Metal ion Fe 3+ and Yb 3+ systems are also discussed, where Fe 3+ to Fe 2+ was ascribed to two-photon absorption and Yb 3+ to Yb 2+ to a reduction followed by solvent ionization.

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“…The pulse interacts with the electron plasma as it being generated, and temporally overlapping ionization cascades eventually lead to the ejection of material. The cross-section for nonlinear absorption depends sensitively upon the pulse characteristics such as duration, energy, frequency and chirp [9]. The detailed structure of the material, including level and type of defects, plays an important role as well [2,[10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Effects of dopant type and concentration on the femtosecond laser ablation threshold and incubation behaviour of silicon

et al. 2016

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150-250 words)In laser micromachining, the ablation threshold (minimum fluence required to cause ablation) is a key performance parameter and overall indicator of the efficiency of material removal. For pulsed-laser micromachining, this important observable depends upon material properties, pulse properties and the number of pulses applied in a complex manner that is not yet well understood. The incubation effect is one example. It manifests as a change in the ablation threshold as a function of number of laser pulses applied, and is driven by photoinduced defect accumulation in the material. Here we study femtosecond (800 nm, 110 fs, 0.1 to 1 mJ/pulse) micromachining of a material with well-defined initial defect concentrations: doped Si across a range of dopant types and concentrations. The single pulse ablation threshold (Fth,1) was observed to decrease with increasing dopant concentration, from a maximum of 0.70 J/cm 2 (± 0.02) for undoped Si, to 0.51 J/cm 2 (± 0.01) for highly N-type doped Si.The effect was greater for N-type doped Si than for P-type, consistent with the higher carrier mobility of electrons compared to holes. In contrast, the infinite pulse ablation threshold (Fth,∞) was the same for all doping levels and types. We attribute this asymptotic behaviour to a maximum defect concentration that is independent of the initial defect concentration and type. These results lend insight into the mechanism of multi-pulse, femtosecond laser ablation. (225 words)

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Effect of input pulse chirp on nonlinear energy deposition and plasma excitation in water

Cited by 25 publications

References 57 publications

Wavelength dependence of nanosecond infrared laser-induced breakdown in water: Evidence for multiphoton initiation via an intermediate state

Wavelength dependence of nanosecond infrared laser-induced breakdown in water: Evidence for multiphoton initiation via an intermediate state

Metal ion reductions by femtosecond laser pulses with micro-Joule energy and their efficiencies

Effects of dopant type and concentration on the femtosecond laser ablation threshold and incubation behaviour of silicon

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