Ultrashort-pulse laser machining of dielectric materials

Perry, M. D.; Stuart, B. C.; Banks, P.S.; Feit, Michael D.; Yanovsky, V.; Rubenchik, A. M.

doi:10.1063/1.370197

Cited by 458 publications

(241 citation statements)

References 19 publications

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“…The interaction of high-intensity and ultra-short electromagnetic fields with condensed matter is an important subject from both fundamental and technological points of view [1][2][3][4]. To investigate dynamics of electrons and phonons in real time, the pump-probe experimental technique has been extensively employed.…”

Section: Introductionmentioning

confidence: 99%

Numerical pump-probe experiments of laser-excited silicon in nonequilibrium phase

et al. 2014

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We calculate the dielectric response of crystalline silicon following irradiation by a high-intensity laser pulse, modeling the dynamics by time-dependent density functional theory (TDDFT). The pump-probe measurements are numerically simulated by solving the time-dependent Kohn-Sham equation with the pump and probe fields included as external fields. As expected, the excited silicon shows features of a particle-hole plasma in its response. We compare the calculated response with a thermal model and with a simple Drude model. The thermal model requires only a static DFT calculation to prepare electronically excited matter and agrees rather well with the TDDFT for the same particle-hole density. The Drude model with two fitted parameters (electron effective mass and collision time) also shows fair agreement at the lower excitation energies; the fitted effective masses are consistent with carrier-band dispersions. The extracted Drude lifetimes range from 6 fs at weak pumping fields to much lower values at high fields. However, we find that the Drude model does not give a good fit to the imaginary dielectric function at the highest fields. Comparing the thermal model with the Drude, we find that the extracted lifetimes are in the same range, 1-13 fs depending on the temperature. These short Drude lifetimes show that strong damping is possible in the TDDFT, despite the absence of electron scattering. One significant difference between the TDDFT response and the other models is that the response to the probe pulse depends on the polarization of the pump pulse. We also find that the imaginary part of the dielectric function can be negative, particularly for the parallel polarization of pump and probe fields.

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Section: Introductionmentioning

confidence: 99%

Numerical pump-probe experiments of laser-excited silicon in nonequilibrium phase

et al. 2014

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“…Experiments showed that the ablation rate in dentin is approximately 1 ~m/pulse which corresponds to removal of 1 mm/sec using a 1 kHz repetition rate system. Scanning electron microscopy (SEM) studies verified lack of collateral damage at the ablation craters [5,6,7,8].…”

Section: Yearmentioning

confidence: 91%

“…A computer-controlled feedback system utilized the high intensity luminescence of calcium at 616 nm and it was used in selective ablation of the bone tissues successfully [10]. Ablation thresholds were measured for hard dental tissues (dentin) and water and it was found that the threshold increases at longer pulse widths [6,11]. It was found that the threshold increased as the square root of pulse width for pulses longer than several picoseconds.…”

Section: Yearmentioning

confidence: 99%

Final Report for High Precision Short-Pulse Laser Ablation System for Medical Applications

Kim¹,

Feit²,

Rubenchik³

et al. 2000

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“…The breakdown takes place when the plasma originated by the avalanche electrons reaches a critical density and transfers energy to lattice ions, which expand away from the surface after the pulse has finished. In metals, the seed electrons are always present (conduction band free electrons), and in dielectrics and semiconductors they are excited from the valence to the conduction band by the pulse leading edge, either by multiphotonic ionization (Kautek et al, 1996;Perry et al, 1999) or by tunneling induced by the laser field (Keldysh, 1965;Lenzner et al, 1998). Although the seed electrons have dissimilar origins in different classes of materials, a metallization occurs in dielectrics and semiconductors after they are produced, and the avalanche evolves deterministically in time (Bass & Fradin, 1973;Du et al, 1994;Joglekar et al, 2003) in the same way in all solids, that behave like metals (Gamaly et al, 2002;Nolte et al, 1997).…”

Section: Ionization By Ultrashort Pulsesmentioning

confidence: 99%