ENERGY TRANSMITTANCE AND SPATIAL PHASE IMPROVEMENT OF INTENSE ULTRASHORT LASER PULSES IN GAS-FILLED HOLLOW FIBER USING PRESSURE GRADIENT METHOD

2004 ◽  
Vol 13 (02) ◽  
pp. 291-299 ◽  
Author(s):  
MUHAMMAD NURHUDA ◽  
HERU BUDIONO ◽  
AKIRA SUDA ◽  
KATSUMI MIDORIKAWA
Keyword(s):  
Femtosecond Laser ◽  
Pressure Gradient ◽  
Hollow Fiber ◽  
Gradient Method ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Input Energy ◽  
Spatial Phase ◽  
Ultrashort Laser

A pressure gradient method for spectral broadening of intense-femtosecond laser pulses in gas-filled hollow fiber is proposed. The simulations using input energy of 6 mJ and pulse duration of 40 fs have shown that using the same value of ∫ p(x)dx, the energy transmittance can be enhanced by a factor of 25% compared to that of using constant gas pressure while the global spatial phase is also improved.

Picosecond Single-Photon and Femtosecond Two-Photon Pulsed Laser Stimulation for IC Characterization and Failure Analysis

2009 ◽  
Author(s):  
V. Pouget ◽  
E. Faraud ◽  
K. Shao ◽  
S. Jonathas ◽  
D. Horain ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Single Photon ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Laser Stimulation ◽  
Two Photon ◽  
Resolution Improvement ◽  
Ultrashort Laser

Abstract This paper presents the use of pulsed laser stimulation with picosecond and femtosecond laser pulses. We first discuss the resolution improvement that can be expected when using ultrashort laser pulses. Two case studies are then presented to illustrate the possibilities of the pulsed laser photoelectric stimulation in picosecond single-photon and femtosecond two-photon modes.

scholarly journals Fabricating waveguide Bragg gratings (WBGs) in bulk materials using ultrashort laser pulses

Nanophotonics ◽  
2017 ◽  
Vol 6 (5) ◽  
pp. 743-763 ◽  
Author(s):  
Martin Ams ◽  
Peter Dekker ◽  
Simon Gross ◽  
Michael J. Withford
Keyword(s):  
Femtosecond Laser ◽  
Ion Beam ◽  
Laser Pulses ◽  
Bragg Gratings ◽  
Femtosecond Laser Pulses ◽  
Ultrafast Laser ◽  
Ultrashort Laser Pulses ◽  
Clean Room ◽  
Bulk Materials ◽  
Ultrashort Laser

AbstractOptical waveguide Bragg gratings (WBGs) can be created in transparent materials using femtosecond laser pulses. The technique is conducted without the need for lithography, ion-beam fabrication methods, or clean room facilities. This paper reviews the field of ultrafast laser-inscribed WBGs since its inception, with a particular focus on fabrication techniques, WBG characteristics, WBG types, and WBG applications.

Localized Electron Evolution Induced by Femtosecond Laser Pulses in Water

2001 ◽  
Author(s):  
C. H. Fan ◽  
J. Sun ◽  
J. P. Longtin
Keyword(s):  
Femtosecond Laser ◽  
Electron Density ◽  
Inhomogeneous Plasma ◽  
Optical Breakdown ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Rate Equations ◽  
Focal Region ◽  
Ultrashort Laser

Abstract Optical breakdown by ultrashort laser pulses in dielectrics presents an efficient method to deposit laser energy into materials that otherwise exhibit minimal absorption at low laser intensities. During optical breakdown, a high density of free electrons is formed in the material, which dominates energy absorption, and, in turn, the material removal rate during ultrafast laser-material processing. Classical models assume spatially uniform electron population and constant laser intensity in the focal region, which results in a time-dependent expressions only, i.e., the rate equations, to predict electron evolution induced by nanosecond and picosecond pulses. For femtosecond pulses, however, the small spatial extent of the pulse requires that the pulse propagation be considered, which results in inhomogeneous plasma and localized electron formation during optical breakdown. In this work, a femtosecond breakdown model is combined with the classical rate equations to determine both time- and position-dependent electron density during femtosecond optical breakdown in water. The model exhibits good agreement when compared with experimental results. For other transparent or moderately absorbing dielectric media, the model also shows promise for determining the time- and position-dependent electron evolution induced by ultrashort laser pulses. Another interesting result is that the maximum electron density formed during femtosecond-laser-induced optical breakdown can exceed the conventional limit imposed by the plasma frequency.

scholarly journals Non-Thermal Processing by Intense Femtosecond Laser Pulses Transmitted through a Hollow Fiber Having an Evacuated Core

2006 ◽  
Vol 34 (7) ◽  
pp. 514-518
Author(s):  
Shinji NISHIKAWA ◽  
Haruyasu ITOH ◽  
Takanori AZUMA ◽  
Shin-ichiro AOSHIMA ◽  
Yutaka TSUCHIYA
Keyword(s):  
Femtosecond Laser ◽  
Hollow Fiber ◽  
Thermal Processing ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses

scholarly journals Rod–sphere cluster irradiation with femtosecond laser pulses: cut and paste at the nanoscale

Nanophotonics ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3153-3159 ◽  
Author(s):  
Pablo Díaz-Núñez ◽  
Sabrina L. J. Thomä ◽  
Guillermo González-Rubio ◽  
Olivia Borrell-Grueiro ◽  
Roland P. M. Höller ◽  
...  
Keyword(s):  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Surface Enhanced ◽  
Fine Control ◽  
Degree Of Control ◽  
The Individual ◽  
Ultrashort Laser ◽  
Individual Particles ◽  
Selection Of

Abstract We report on the irradiation of gold rod–sphere assemblies with ultrashort laser pulses, producing structures that are very difficult to obtain by other methods. The optical response of these assemblies displays several peaks arising from the interaction of the plasmon modes of the individual particles, offering thus great flexibility to control the energy deposited on the individual particles. Judicious selection of the wavelength and fluence of the laser pulses allow fine control over the changes produced: the particles can be melted, welded and/or the organic links cleaved. In this way, it is possible to generate structures “à la carte” with a degree of control unmatched by other synthetic protocols. The method is exemplified with gold nanoparticles, but it can be easily implemented on particles composed of different metals, widening considerably the range of possibilities. The final structures are excellent candidates for surface-enhanced spectroscopies or plasmonic photothermal therapy as they have a very intense electric field located outside the structure, not in the gaps.

scholarly journals Femtosecond Laser Assisted Crystallization of Gold Thin Films

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1186
Author(s):  
Ayesha Sharif ◽  
Nazar Farid ◽  
Rajani K. Vijayaraghavan ◽  
Patrick J. McNally ◽  
Gerard M. O’Connor
Keyword(s):  
Thin Films ◽  
Femtosecond Laser ◽  
Quartz Substrate ◽  
Damage Threshold ◽  
Laser Pulses ◽  
Industrial Applications ◽  
Ultrashort Laser Pulses ◽  
Gold Films ◽  
Gold Thin Films ◽  
Ultrashort Laser

We propose a novel low temperature annealing method for selective crystallization of gold thin films. Our method is based on a non-melt process using highly overlapped ultrashort laser pulses at a fluence below the damage threshold. Three different wavelengths of a femtosecond laser with the fundamental (1030 nm), second (515 nm) and third (343 nm) harmonic are used to crystallize 18-nm and 39-nm thick room temperature deposited gold thin films on a quartz substrate. Comparison of laser wavelengths confirms that improvements in electrical conductivity up to 40% are achievable for 18-nm gold film when treated with the 515-nm laser, and the 343-nm laser was found to be more effective in crystallizing 39-nm gold films with 29% improvement in the crystallinity. A two-temperature model provides an insight into ultrashort laser interactions with gold thin films and predicts that applied fluence was insufficient to cause melting of gold films. The simulation results suggest that non-equilibrium energy transfer between electrons and lattice leads to a solid-state and melt-free crystallization process. The proposed low fluence femtosecond laser processing method offers a possible solution for a melt-free thin film crystallization for wide industrial applications.

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