Nanosecond-to-femtosecond laser-induced breakdown in dielectrics

Stuart, B. C.; Feit, Michael D.; Herman, S.; Rubenchik, Alexander M.; Shore, Bruce W.; Perry, M. D.

doi:10.1103/physrevb.53.1749

Cited by 1,413 publications

(946 citation statements)

References 34 publications

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“…It has long been recognized that material removal by ablation strongly depends on the material's properties and the parameters of the laser pulse like fluence, wavelength, and pulse duration. [44][45][46][47][48][49][50][51][52][53][54] The complexity of the ablation process is related to the coupling mechanism of the laser light to the sample as the optical and thermal properties may change considerably upon laser exposure due to heating, formation of excited species, phase transitions, plasma formation, and photochemical reactions. In particular, it has been recognized [44][45][46][47][48][49][50][51][52][53][54] that for ablation of metals short laser pulses have a great advantage because (i) during the laser pulse no free (transparent) plasma can develop; (ii) heat diffusion into the material is negligible.…”

Section: Resultsmentioning

confidence: 99%

Laser-Induced Shape Changes of Colloidal Gold Nanorods Using Femtosecond and Nanosecond Laser Pulses

2000

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Gold nanorods have been found to change their shape after excitation with intense pulsed laser irradiation. The final irradiation products strongly depend on the energy of the laser pulse as well as on its width. We performed a series of measurements in which the excitation power was varied over the range of the output power of an amplified femtosecond laser system producing pulses of 100 fs duration and a nanosecond optical parametric oscillator (OPO) laser system having a pulse width of 7 ns. The shape transformations of the gold nanorods are followed by two techniques: (1) visible absorption spectroscopy by monitoring the changes in the plasmon absorption bands characteristic for gold nanoparticles; (2) transmission electron microscopy (TEM) in order to analyze the final shape and size distribution. While at high laser fluences (∼1 J cm -2 ) the gold nanoparticles fragment, a melting of the nanorods into spherical nanoparticles (nanodots) is observed when the laser energy is lowered. Upon decreasing the energy of the excitation pulse, only partial melting of the nanorods takes place. Shorter but wider nanorods are observed in the final distribution as well as a higher abundance of particles having odd shapes (bent, twisted, φ-shaped, etc.). The threshold for complete melting of the nanorods with femtosecond laser pulses is about 0.01 J cm -2 . Comparing the results obtained using the two different types of excitation sources (femtosecond vs nanosecond laser), it is found that the energy threshold for a complete melting of the nanorods into nanodots is about 2 orders of magnitude higher when using nanosecond laser pulses than with femtosecond laser pulses. This is explained in terms of the successful competitive cooling process of the nanorods when the nanosecond laser pulses are used. For nanosecond pulse excitation, the absorption of the nanorods decreases during the laser pulse because of the bleaching of the longitudinal plasmon band. In addition, the cooling of the lattice occurring on the 100 ps time scale can effectively compete with the rate of absorption in the case of the nanosecond pulse excitation but not for the femtosecond pulse excitation. When the excitation source is a femtosecond laser pulse, the involved processes (absorption of the photons by the electrons (100 fs), heat transfer between the hot electrons and the lattice (<10 ps), melting (30 ps), and heat loss to the surrounding solvent (>100 ps) are clearly separated in time.

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Section: Resultsmentioning

confidence: 99%

Laser-Induced Shape Changes of Colloidal Gold Nanorods Using Femtosecond and Nanosecond Laser Pulses

2000

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“…For such pulses, the electron dynamics in the timedependent field of the pulse be described in terms of the density matrix whose evolution is determined by rate equations with phenomenological relaxation and generation times [19][20][21][22][23] . In this description, the effect of the pulse electric field is restricted to generation of an electronhole plasma through multiphoton or collisional ionization processes.…”

Section: Introductionmentioning

confidence: 99%

Theory of dielectric nanofilms in strong ultrafast optical fields

Apalkov

Stockman

2012

Phys. Rev. B

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We theoretically predict that a dielectric nanofilm subjected to a normally-incident strong but ultrashort (a few optical oscillations) laser pulse exhibits deeply nonlinear (non-perturbative) optical responses which are essentially reversible and driven by the instantaneous optical field. Among them is a high optical polarization and a significant population of the conduction band, which develop at the peak of the pulse and almost disappear after its end. There is also a correspondingly large increase of the pulse reflectivity. These phenomena are related to Wannier-Stark localization and anticrossings between the Wannier-Stark ladders originating from the valence and conduction bands leading to optical "softening" of the dielectric. Theory is developed by solving self-consistently the Maxwell equations and the time-dependent Schrödinger equation. The results point out to a fundamental possibility of optical-field effect devices with the bandwidth on the order of optical frequency.

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“…Hence, femtosecond laser ablation can yield precise materials processing resulting from efficient energy deposition while simultaneously minimizing heat conduction and thermal damage to surrounding material. Focussed intensities I>10 13 W/cm 2 are easily obtained with micro-joule pulses and the processing of, for example, normally transparent dielectrics can be achieved through multi-photon absorption [113]. Metals can be ablated quite easily [114] and the absence of a heat affected zone (HAZ), like in ordinary nspulse material processing, makes femtosecond pulse micro-machining a fast developing technology.…”

Section: Ultrafast Plasma Modelingmentioning

confidence: 99%