Topic
Fluence
About: Fluence is a research topic. Over the lifetime, 6156 publications have been published within this topic receiving 94486 citations.
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TL;DR: In this paper, the mechanisms responsible for the growth of periodic surface structure on Ge irradiated by 1.06-m laser pulses from a single beam are investigated using time-resolved diffraction of a weak cw probe beam from the developing structures, coupled with electron-microscope pictures of the resulting morphology.
Abstract: The mechanisms responsible for the growth of periodic surface structure on Ge irradiated by 1.06-\ensuremath{\mu}m laser pulses from a single beam are investigated. Time-resolved diffraction of a weak cw probe beam from the developing structures, coupled with electron-microscope pictures of the resulting morphology, is used to identify four distinct regimes of ripple formation at different incident laser fluences. At low fluences, the structure develops when thin (1 \ensuremath{\mu}M wide) isolated, molten strips resolidify on the solid substrate, while at high fluences, the structure results from freezing of capillary waves which are generated on the surface that the laser pulse has melted uniformly. Models are presented which clearly demonstrate how the incident electromagnetic field interacts with the evolving structures (in different fluence regimes) to provide feedback mechanisms which sustain their growth.
289 citations
TL;DR: A five-level model of C60 yields excellent agreement with both pulse-width data sets for incident fluences as high as approximately 1 J/cm2 and additional phenomena observed at higher fluences indicate that other mechanisms may be active and contribute to optical limiting in this regime.
Abstract: Nonlinear absorption at 532 nm in a C60–toluene solution by using 8-ns and 30-ps laser pulses is reported. The transmittance for both pulse widths is fluence dependent. A five-level model of C60 is described that yields excellent agreement with both pulse-width data sets for incident fluences as high as approximately 1 J/cm2. Additional phenomena observed at higher fluences indicate that other mechanisms may be active and contribute to optical limiting in this regime. The application of C60 as an optical limiter material is discussed.
284 citations
TL;DR: In this paper, the authors reported the observation of visible light emission at room temperature from high fluence (0.3-3×1017 cm−2) Si+ implanted thermal SiO2 layers grown on silicon substrates.
Abstract: We report the observation of visible‐light emission at room temperature from high fluence (0.3–3×1017 cm−2) Si+ implanted thermal SiO2 layers grown on silicon substrates. Significant blue‐light emission and an intense broad luminescent band with a peak beyond 750 nm are observed after annealing at high temperature (T≥1000 °C). The red‐light emission, present only in the highest fluence implant, is attributed to the luminescence emitted from silicon nanocrystals produced by silicon precipitation. The presence of silicon nanocrystals is confirmed by transmission electron microscopy. Significant blue‐light emission is visible after thermal annealing in the 1×1017 cm−2 fluence implant. The peak position shifts from 490 to 540 nm by increasing the annealing cycles temperature.
282 citations
IBM1
TL;DR: When a pulse (~ 14 nsec half width) of laser radiation of 193 nm wavelength with a fluence above a threshold value falls on a polymer film, the material at the irradiation site is spontaneously etched away to a depth of 1000 A or more.
Abstract: When a pulse (~ 14 nsec half-width) of laser radiation of 193 nm wavelength with a fluence above a threshold value falls on a polymer film, the material at the irradiation site is spontaneously etched away to a depth of 1000 A or more.[1,2] This process has been called Ablative Photo Decomposition’ [3]. The excimer laser which is the source of the 193 nm radiation is capable of providing radiation at other wavelengths such as 249 nm, 308 nm, and 351 nm. Spontaneous etching of the polymer films by the laser beam has been observed at all of these wavelengths [4–7].But there are quantitative differences in the etching process at different wavelengths and with different polymers.
269 citations
TL;DR: In this article, femtosecond laser pulses were applied to study the energy deposition depth and transfer to the lattice for Au, Ni, and Mo films of varying thickness, and the onset of melting, defined here as damage threshold, was detected by measuring changes in the scattering, reflection and transmission of the incident light.
Abstract: Femtosecond laser pulses were applied to study the energy deposition depth and transfer to the lattice for Au, Ni, and Mo films of varying thickness. The onset of melting, defined here as damage threshold, was detected by measuring changes in the scattering, reflection and transmission of the incident light. Experiments were done in multi-shot mode and single-shot threshold fluences were extracted by taking incubation into account. Since melting requires a well-defined energy density, we found the threshold depends on the film thickness whenever this is smaller than the range of electronic energy transport. The dependence of the threshold fluence on the pulse length and film thickness can be well described by the two-temperature model, proving that laser damage in metals is a purely thermal process even for femtosecond pulses. The importance of electron–phonon coupling is reflected by the great difference in electron diffusion depths of noble and transition metals.
262 citations