Oscillatory mechanism of ultrafast bias-free conversion of few-cycle laser pulses to photocurrent and its influence on laser processing of non-metal materials

2021 ◽  
Author(s):  
Vitaly E. Gruzdev ◽  
Olga Sergaeva
Keyword(s):  
Laser Processing ◽  
Laser Pulses ◽  
Oscillatory Mechanism ◽  
Metal Materials

scholarly journals DEVELOPMENT OF ULTRA-SHORT HIGH INTENSITY LASERS FOR THE VISIBLE SPECTRA RANGE

2020 ◽  
Vol 17 (35) ◽  
pp. 739-752
Author(s):  
Hayder J. ABDULRAHMAN ◽  
Suzan B. MOHAMMED
Keyword(s):  
High Intensity ◽  
Laser Processing ◽  
Near Infrared ◽  
Laser Pulses ◽  
Dielectric Materials ◽  
Infrared Light ◽  
Near Infrared Light ◽  
Visible Spectra ◽  
Short Laser Pulses ◽  
Micro Tools

Ultra-short laser pulses are particularly suitable for processing micro tools made of ultra-hard and dielectric materials. Ultra-short laser pulses provide a contact-free and precise fabrication of heat-sensitive materials such as visible spectra range. Visible spectra range has unique properties, which makes it an essential material in the tool, jewelry, and semiconductor industries. The processing of visible spectra range by ultra-short laser pulses is complex, as visible and near-infrared light is generally not absorbed. However, the intensity of ultra-short laser pulses is extremely high, so that the absorption scales nonlinearly with the intensity and, thus, visible or near-infrared light can be absorbed. The complexity also results from many partially interdependent process variables, such as the repetition rate, pulse overlap, track overlap, and scan speed. Excellent knowledge of the process is, therefore, essential for the production of micro tools. To make the laser processing accessible to a broader user field, the operator can be supported by a computer-aided design (CAD). The aim of this research was to the modeling of an ultra-short high-intensity laser for the visible spectra range in different environments of the angle of incidence, scanning speed, pulse, and track overlap. The experimental process included ultra-short pulsed laser processing of visible spectra range and surface analysis concerning modifications and ablation of the ultra-short laser. Ablation volumes were analyzed for single pulses, multi-pulses, and pockets. Pump-probe experiments reveal transient optical properties such as transmission or reflectivity. It was concluded that ultraviolet laser pulses are best suited to induce damage or modifications to visible spectra range surfaces. Additionally, shorter wavelengths have further advantages such as potentially longer Rayleigh lengths and smaller spot sizes.

One-Step Fabrication and Functionalization of Nanostructured Silicon Surfaces for Advanced Sensing Applications

2020 ◽  
Vol 312 ◽  
pp. 154-159
Author(s):  
Alexander Yuryevich Mironenko ◽  
Mikhail Tutov ◽  
Alexander Konstantinovich Chepak ◽  
Eugeny Mitsai ◽  
Alexander A. Sergeev ◽  
...  
Keyword(s):  
Laser Processing ◽  
Laser Energy ◽  
High Spatial Frequency ◽  
Laser Pulses ◽  
Successful Implementation ◽  
Experimental Conditions ◽  
Sensing Applications ◽  
Direct Laser ◽  
Fs Laser ◽  
One Step

Direct laser processing of various materials with nano- and femtosecond (fs) laser pulses is known to be a facile and inexpensive technology for fabrication of various surface morphologies. Since ultrafast deposition of the laser energy to target material typically creates unique experimental conditions with extremely high pressure and temperature, we hypothesized that carrying out this process in anhydrous non-oxidizing environment containing functionalizing agent (fluorophore with vinyl functional group) will allow one-step fabrication and subsequent functionalization of the surface of high-n material. In this paper, we demonstrate successful implementation of this idea by fabricating high-spatial-frequency laser-induced periodic surface structures (LIPSS) via direct fs-pulse ablation of bulk crystalline Si wafer immersed in solution of N-vinylcarbazole in toluene. Laser processing with linearly polarized fs-laser pulses was found to produce LIPSS with a characteristic period around 100 nm functionalized with N-vinylcarbazole molecules via photo-activated hydrosililation reaction. The unique LIPSS with hierarchical roughness and remarkable light trapping performance functionalized with sensory fluorophore show high sensitivity due to implementation of surface enhanced fluorescence effect. By using N-vinylcarbazole as functionalizing agent we demonstrate one-step fabrication of high-performance sensor for detecting nitrobenzene in water with a detection limit of 40 nM.

Femtosecond Ti:Sa Laser Processing of Silica

2015 ◽  
Vol 752-753 ◽  
pp. 452-457
Author(s):  
Michael Babiy ◽  
Yuliya Biryukova ◽  
Sergey Golik ◽  
Vladimir Lisitsa
Keyword(s):  
Femtosecond Laser ◽  
Laser Processing ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Silicon Sample ◽  
Opposite Edge ◽  
Mechanical Vibrations ◽  
Ongoing Process ◽  
Edge Sharpening

The result of direct ablation of silicon by an 800 nm Ti:Sa femtosecond laser pulses are presented. Obtained slice of silicon with submicron roughness with tilt focused femtosecond laser pulses. Yaw cut more due to mechanical vibrations of the entire installation on a pneumatic table, but not the physics of the ongoing process. During processing, possibly thinning the silicon sample from the opposite edge (sharpening) to submicron values ​​(tens of nanometers).

Residual heat generated during laser processing of CFRP with picosecond laser pulses

2018 ◽  
Vol 7 (3) ◽  
pp. 157-163
Author(s):  
Christian Freitag ◽  
Leon Pauly ◽  
Daniel J. Förster ◽  
Margit Wiedenmann ◽  
Rudolf Weber ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Heat Affected Zone ◽  
Laser Processing ◽  
Picosecond Laser ◽  
Theoretical Models ◽  
Laser Pulses ◽  
Groove Depth ◽  
Interaction Zone ◽  
Heat Accumulation ◽  
Residual Heat

Abstract One of the major reasons for the formation of a heat-affected zone during laser processing of carbon fiber-reinforced plastics (CFRP) with repetitive picosecond (ps) laser pulses is heat accumulation. A fraction of every laser pulse is left as what we termed residual heat in the material also after the completed ablation process and leads to a gradual temperature increase in the processed workpiece. If the time between two consecutive pulses is too short to allow for a sufficient cooling of the material in the interaction zone, the resulting temperature can finally exceed a critical temperature and lead to the formation of a heat-affected zone. This accumulation effect depends on the amount of energy per laser pulse that is left in the material as residual heat. Which fraction of the incident pulse energy is left as residual heat in the workpiece depends on the laser and process parameters, the material properties, and the geometry of the interaction zone, but the influence of the individual quantities at the present state of knowledge is not known precisely due to the lack of comprehensive theoretical models. With the present study, we, therefore, experimentally determined the amount of residual heat by means of calorimetry. We investigated the dependence of the residual heat on the fluence, the pulse overlap, and the depth of laser-generated grooves in CRFP. As expected, the residual heat was found to increase with increasing groove depth. This increase occurs due to an indirect heating of the kerf walls by the ablation plasma and the change in the absorbed laser fluence caused by the altered geometry of the generated structures.

scholarly journals High-Repetition-Rate Femtosecond Laser Processing of Acrylic Intra-Ocular Lenses

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 242 ◽  
Author(s):  
Daniel Sola ◽  
Rafael Cases
Keyword(s):  
Femtosecond Laser ◽  
Repetition Rate ◽  
Laser Processing ◽  
Refractive Index Change ◽  
Laser Pulses ◽  
Processing Parameters ◽  
High Repetition Rate ◽  
Femtosecond Laser Pulses ◽  
Periodic Patterns ◽  
High Repetition

The study of laser processing of acrylic intra-ocular lenses (IOL) by using femtosecond laser pulses delivered at high-repetition rate is presented in this work. An ultra-compact air-cooled femtosecond diode laser (HighQ2-SHG, Spectra-Physics) delivering 250 fs laser pulses at the fixed wavelength of 520 nm with a repetition rate of 63 MHz was used to process the samples. Laser inscription of linear periodic patterns on the surface and inside the acrylic substrates was studied as a function of the processing parameters as well as the optical absorption characteristics of the sample. Scanning Electron Microscopy (SEM) Energy Dispersive X-ray Spectroscopy (EDX), and micro-Raman Spectroscopy were used to evaluate the compositional and microstructural changes induced by the laser radiation in the processed areas. Diffractive characterization was used to assess 1st-order efficiency and the refractive index change.

Laser processing of GaN-based LEDs with ultraviolet picosecond laser pulses

2012 ◽  
Author(s):  
Rüdiger Moser ◽  
Michael Kunzer ◽  
Christian Goßler ◽  
Ralf Schmidt ◽  
Klaus Köhler ◽  
...  
Keyword(s):  
Laser Processing ◽  
Picosecond Laser ◽  
Laser Pulses ◽  
Picosecond Laser Pulses

Laser processing of gallium nitride–based light-emitting diodes with ultraviolet picosecond laser pulses

2012 ◽  
Vol 51 (11) ◽  
pp. 114301 ◽  
Author(s):  
Rüdiger Moser ◽  
Michael Kunzer ◽  
Christian Goßler ◽  
Klaus Köhler ◽  
Wilfried Pletschen ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Laser Processing ◽  
Light Emitting Diodes ◽  
Picosecond Laser ◽  
Laser Pulses ◽  
Light Emitting ◽  
Picosecond Laser Pulses

scholarly journals Enhancement of Surface Properties of Metal Materials by Underwater Laser Processing

2008 ◽  
Vol 36 (APLS) ◽  
pp. 1195-1198 ◽  
Author(s):  
Yuji SANO ◽  
Naruhiko MUKAI ◽  
Yoshinobu MAKINO ◽  
Masataka TAMURA ◽  
Minoru OBATA ◽  
...  
Keyword(s):  
Surface Properties ◽  
Laser Processing ◽  
Metal Materials ◽  
Underwater Laser

Laser processing of noble metal doped glasses by femto- and nanosecond laser pulses

2019 ◽  
Vol 475 ◽  
pp. 479-486 ◽  
Author(s):  
N. Nedyalkov ◽  
N.E. Stankova ◽  
M.E. Koleva ◽  
R. Nikov ◽  
L. Aleksandrov ◽  
...  
Keyword(s):  
Noble Metal ◽  
Laser Processing ◽  
Laser Pulses ◽  
Nanosecond Laser ◽  
Doped Glasses ◽  
Nanosecond Laser Pulses ◽  
Metal Doped

scholarly journals Laser and Material Parameter Dependence of the Chemical Modifications in the UV Laser Processing of Model Polymeric Solids

2002 ◽  
Vol 20 (1) ◽  
pp. 1-21 ◽  
Author(s):  
E. Andreou ◽  
A. Athanassiou ◽  
D. Fragouli ◽  
D. Anglos ◽  
S. Georgiou
Keyword(s):  
Laser Processing ◽  
Laser Pulses ◽  
Model Systems ◽  
Critical Parameters ◽  
Major Type ◽  
Uv Laser ◽  
Chemical Modifications ◽  
Good Surface ◽  
Molecular Substrates ◽  
Processing Techniques

Chemical modifications are expected to be the major type of side-effect in the UV laser processing of molecular substrates. For their systematic characterization, studies on polymeric systems consisting of poly(methyl methacrylate) and polystyrene films doped with aromatic dopants exemplifying different degrees of photoreactivity are undertaken. In particular, the dependence of the nature and extent of the modifications on chromophore properties and laser parameters (laser fluence, wavelength, and number of pulses) is examined. The substrate absorptivity and the number of employed laser pulses turn out to be the critical parameters in determining the quantity and nature of photoproducts that remain in the substrate. The implications of these results for the optimisation of laser processing of molecular/organic solids are discussed. It is suggested that the importance of employing relatively strongly absorbed wavelengths in laser processing may relate, besides the efficient etching and good surface morphology, to the minimization of the chemical modifications. In contrast, irradiation with successive laser pulses is indicated to be highly disadvantageous for the chemical integrity of the substrate. In all, the study of such model systems appears to be most appropriate for establishing criteria for the systematic optimisation of laser processing techniques of molecular substrates.

Sign in / Sign up

Export Citation Format

Share Document