We report on the role of local optical field enhancement in the neighborhood of particles during ... more We report on the role of local optical field enhancement in the neighborhood of particles during dry laser cleaning (DLC) of silicon wafer surfaces. Samples covered with spherical colloidal particles (PS, SiO2) and arbitrarily shaped Al2O3 particles with diameters from 320–1700 nm were cleaned using laser pulses with durations from 150 fs to 6.5 ns and wavelengths ranging from 400–800 nm. Cleaned areas were investigated with scanning electron and atomic force microscopy. Holes in the substrate with diameters of 200–400 nm and depths of 10–80 nm, depending on the irradiation conditions, were found at the former positions of the particles. For all pulse durations analyzed (fs, ps, ns), holes are created at laser fluences as small as the threshold fluence. Calculations of the optical field intensities in the particles’ neighbourhood by applying Mie theory suggest that enhancement of the incident laser intensity in the near field of the particles is responsible for these effects. DLC for sub-ns pulses seems to be governed by the local ablation of the substrate rather than by surface acceleration.
A differential optical transmission technique has been used to monitor in situ the efficiency of ... more A differential optical transmission technique has been used to monitor in situ the efficiency of laser cleaning for the removal of sub-micrometer-sized particles on substrates transparent at the monitoring wavelength. This technique has been applied to the removal of sub-micrometer polystyrene particles on polyimide substrates using laser pulses of 30 ps duration at 292 nm while probing the material transmission at 633 nm. The sensitivity achieved -1/104 for the transmission changes induced upon single-pulse laser exposure – allows us to monitor the removal of just a few sub-micron-sized particles from the probed region inside the irradiated area.
We investigate beam propagation in a heavy-metal-oxide glass of the group Nb 2 O 5 PbOGeO 2 usi... more We investigate beam propagation in a heavy-metal-oxide glass of the group Nb 2 O 5 PbOGeO 2 using picosecond pulses in the near infrared. We observe a wavelength-dependent self-focusing, with beam collapse and modulation instability in the Kerr regime at 1.064 ...
This paper reviews the work we have carried out over the last years on the development of ultrash... more This paper reviews the work we have carried out over the last years on the development of ultrashort-laser-pulse-driven, rewritable, phase-change optical memories. The materials we have tailored for this application are non-stoichiometric, Sb-rich amorphous thin films, which can be crystallized upon irradiation with ultrashort laser pulses, showing a large optical contrast upon transformation. This result makes them very promising for the development of rewritable phase-change optical memories under ultrashort pulses, since the reversibility of the process has also been demonstrated. Adequate control of the heat-flow conditions has allowed us to achieve a full transformation time faster than 400 ps for crystallization/amorphization using 30-ps pulses. The crystallization threshold fluence has been found to decrease upon irradiation with pulses shorter than 800 fs, thus suggesting the relevance of high-electronic-excitation-induced processes in the amorphous-to-crystalline phase transition. This has been confirmed by the observation of an ultrafast, non-thermal phase transition occurring 200–300 fs after the arrival of the laser pulse at the surface, for fluences above the crystallization threshold. The presence of this transient phase conditions the final state induced therefore enabling the applicability of this material as a rewritable recording medium using femtosecond pulses.
We report on the role of local optical field enhancement in the neighborhood of particles during ... more We report on the role of local optical field enhancement in the neighborhood of particles during dry laser cleaning (DLC) of silicon wafer surfaces. Samples covered with spherical colloidal particles (PS, SiO2) and arbitrarily shaped Al2O3 particles with diameters from 320–1700 nm were cleaned using laser pulses with durations from 150 fs to 6.5 ns and wavelengths ranging from 400–800 nm. Cleaned areas were investigated with scanning electron and atomic force microscopy. Holes in the substrate with diameters of 200–400 nm and depths of 10–80 nm, depending on the irradiation conditions, were found at the former positions of the particles. For all pulse durations analyzed (fs, ps, ns), holes are created at laser fluences as small as the threshold fluence. Calculations of the optical field intensities in the particles’ neighbourhood by applying Mie theory suggest that enhancement of the incident laser intensity in the near field of the particles is responsible for these effects. DLC for sub-ns pulses seems to be governed by the local ablation of the substrate rather than by surface acceleration.
A differential optical transmission technique has been used to monitor in situ the efficiency of ... more A differential optical transmission technique has been used to monitor in situ the efficiency of laser cleaning for the removal of sub-micrometer-sized particles on substrates transparent at the monitoring wavelength. This technique has been applied to the removal of sub-micrometer polystyrene particles on polyimide substrates using laser pulses of 30 ps duration at 292 nm while probing the material transmission at 633 nm. The sensitivity achieved -1/104 for the transmission changes induced upon single-pulse laser exposure – allows us to monitor the removal of just a few sub-micron-sized particles from the probed region inside the irradiated area.
We investigate beam propagation in a heavy-metal-oxide glass of the group Nb 2 O 5 PbOGeO 2 usi... more We investigate beam propagation in a heavy-metal-oxide glass of the group Nb 2 O 5 PbOGeO 2 using picosecond pulses in the near infrared. We observe a wavelength-dependent self-focusing, with beam collapse and modulation instability in the Kerr regime at 1.064 ...
This paper reviews the work we have carried out over the last years on the development of ultrash... more This paper reviews the work we have carried out over the last years on the development of ultrashort-laser-pulse-driven, rewritable, phase-change optical memories. The materials we have tailored for this application are non-stoichiometric, Sb-rich amorphous thin films, which can be crystallized upon irradiation with ultrashort laser pulses, showing a large optical contrast upon transformation. This result makes them very promising for the development of rewritable phase-change optical memories under ultrashort pulses, since the reversibility of the process has also been demonstrated. Adequate control of the heat-flow conditions has allowed us to achieve a full transformation time faster than 400 ps for crystallization/amorphization using 30-ps pulses. The crystallization threshold fluence has been found to decrease upon irradiation with pulses shorter than 800 fs, thus suggesting the relevance of high-electronic-excitation-induced processes in the amorphous-to-crystalline phase transition. This has been confirmed by the observation of an ultrafast, non-thermal phase transition occurring 200–300 fs after the arrival of the laser pulse at the surface, for fluences above the crystallization threshold. The presence of this transient phase conditions the final state induced therefore enabling the applicability of this material as a rewritable recording medium using femtosecond pulses.
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Papers by Javier Solis