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V Photo Contest “Day of Light”

V Photo Contest “Day of Light”

On the occasion of the proclamation of May 16 as “International Day of Light and Light-Based Technologies” by the United Nations Organization, the Master’s Degree in Laser Physics and Technology” announces the V edition of the Photo Contest “Day of the light”.

In the organization of the contest and formation of the jury participate:

The contest is open to undergraduate, master’s or doctoral students, professors and members of the university community of the University of Salamanca and the University of Valladolid, as well as graduates of the Master’s Degree in Laser Physics and Technology who are not part of the jur

The participation period is open until May 12. Each participant can send up to two photographs to each of the established categories:

  • Technologies of light and Optical Phenomena
  • The laser

4 prizes will be awarded:

  • First prize in the Light Technologies and Optical Phenomena category: 200 euros.
  • Second prize in the Light Technologies and Optical Phenomena category: 100 euros.
  • First prize in the Laser category: 200 euros.
  • Second prize in the Laser category: 100 euros.

In addition, those winners who are undergraduate, master’s or doctoral students will receive one year of free subscription to the Royal Spanish Physics Society with online access to the Physics Journal. The winning photographs will be published in the Pure and Applied Optics magazine of the Spanish Optical Society (SEDOPTICA).

The complete rules of the competition are available on the website of the Master’s Degree in Physics and Technology of Lasers (laser.usal.es/posgrado)

Organizacion concurso 2023
29 March, 2023 admin , No comments
adminV Photo Contest “Day of Light”

OP Session – Coulomb explosion as a potential new tool for the ultrafast imaging of single molecules

OP Session – Coulomb explosion as a potential new tool for the ultrafast imaging of single molecules

Benoit Richard, researcher in the Hamburg University, will give the seminar entitled “Coulomb explosion as a potential new tool for the ultrafast imaging of single molecules” on February 24 at 12:00.

The seminar will take place in classroom VII of the Edificio Trilingüe at the University of Salamanca.

18 January, 2023 admin No comments
adminOP Session – Coulomb explosion as a potential new tool for the ultrafast imaging of single molecules

Use of ultrashort laser pulses as a standard for fracture resistance testing

Use of ultrashort laser pulses as a standard for fracture resistance testing

The use of fracture mechanics for rationalizing the fracture behavior of cemented carbides is valid, as far as sharp cracks, free of residual stresses and subjected to a well-defined stress state are used for assessing fracture toughness. However, machining a very sharp notch on the surface of hardmetals for fracture toughness testing has been a critical issue during many years. Within this context, introduction of surface “through-thickness” _micronotches (SEμVNB) by means of ultrashort pulsed laser ablation (UPLA) is here proposed, implemented and analyzed as an innovative precracking-like route within flexural testing procedures for appropiated evaluation of fracture toughness of cemented carbides. UPLA parameters used for introducing the micronotch are optimized in terms of induced damage ahead of the notch tip. For comparison purposes, fracture toughness is also determined by means of flexural testing of previously cracked single-edge notch beams (SENB-Cracked) as well as specimens with V-notch tips sharpened through diamond polishing using a razor blade, and Palmqvist indentation microfracture method. The satisfactory agreement found between values measured using UPLA-micronotched and SENB-Cracked (reference) specimens allows to conclude that flexural testing of SEμVNB samples is a valid methodology for reliable determination of fracture toughness of hardmetals. This is feasible because of the extremely short time of laser-matter interaction. It yields small and somehow controlled damage in front of the notch tip as a result of shock wave propagation during ablation, which translates into effective precracking of SEμVNB specimens

More information at:  

Ortiz-Membrado, L., Liu, C., Prada-Rodrigo, J., Jiménez-Piqué, E., Lin, L. L., Moreno, P., Wang, M. S., & Llanes, L. (2022). Assessment of fracture toughness of cemented carbides by using a shallow notch produced by ultrashort pulsed laser ablation, and a comparative study with tests employing precracked specimens. International Journal of Refractory Metals and Hard Materials, 108, 105949. https://doi.org/10.1016/j.ijrmhm.2022.105949
25 December, 2022 admin , No comments
adminUse of ultrashort laser pulses as a standard for fracture resistance testing

LIPSS-induced surface modification of thin films

LIPSS-induced surface modification of thin films

In this work, the formation of laser-induced periodic surface structures (LIPSS) on the surfaces of thin films of poly(ethylene terephthalate) (PET) and PET reinforced with expanded graphite (EG) was studied. Laser irradiation was carried out by ultraviolet (265 nm) and near-infrared (795 nm) femtosecond laser pulses, and LIPSS were formed in both materials. In all cases, LIPSS had a period close to the irradiation wavelength and were formed parallel to the polarization of the laser beam, although, in the case of UV irradiation, differences in the formation range were observed due to the different thermal properties of the neat polymer in comparison to the composite. To monitor the modification of the physicochemical properties of the surfaces after irradiation as a function of the laser wavelength and of the presence of the filler, different techniques were used. Contact angle measurements were carried out using different reference liquids to measure the wettability and the solid surface free energies. The initially hydrophilic surfaces became more hydrophilic after ultraviolet irradiation, while they evolved to become hydrophobic under near-infrared laser irradiation. The values of the surface free energy components showed changes after nanostructuring, mainly in the polar component. Additionally, for UV-irradiated surfaces, adhesion, determined by the colloidal probe technique, increased, while, for NIR irradiation, adhesion decreased. Finally, nanomechanical properties were measured by the PeakForce Quantitative Nanomechanical Mapping method, obtaining maps of elastic modulus, adhesion, and deformation. The results showed an increase in the elastic modulus in the PET/EG, confirming the reinforcing action of the EG in the polymer matrix. Additionally, an increase in the elastic modulus was observed after LIPSS formation

More info at:

Rodríguez-Beltrán, R. I., Prada-Rodrigo, J., Crespo, A., Ezquerra, T. A., Moreno, P., & Rebollar, E. (2022). Physicochemical Modifications on Thin Films of Poly(Ethylene Terephthalate) and Its Nanocomposite with Expanded Graphite Nanostructured by Ultraviolet and Infrared Femtosecond Laser Irradiation. Polymers, 14(23), 5243. https://doi.org/10.3390/polym14235243
25 November, 2022 admin No comments
adminLIPSS-induced surface modification of thin films

OP Session – Microscopía Multifotónica: donde cabe uno caben dos (o más)

OP Session – Microscopía Multifotónica: donde cabe uno caben dos (o más)

Rosa M. Martínez-Ojeda, predoctoral researcher in the University of Murcia, will give the seminar entitled “Microscopia multifotónica: donde cabe uno caben dos (o más)” on November 25 at 13:00.

The seminar will take place in classroom VII of the Edificio Trilingüe at the University of Salamanca.

17 November, 2022 admin No comments
adminOP Session – Microscopía Multifotónica: donde cabe uno caben dos (o más)

ALF-USAL researchers participate in the annual meeting of the European Optical Society (EOSAM 2022)

ALF-USAL researchers participate in the annual meeting of the European Optical Society (EOSAM 2022)

From September 12 to 16, the annual meeting of the European Optical Society (EOSAM 2022) was held in Porto (Portugal). The Laser and Photonics Applications group (ALF – USAL) has participated in this conference presenting some of the most recent results of the research it is currently carrying out.

The works presented were:

  • Marina Fernández Galán, Enrique Conejero Jarque, Julio San Román. Pulse self-compression down to the sub-cycle regime in hollow capillary fibers with decreasing pressure gradients. TOM 8 Non-linear and Quantum Optics – Oral contribution (Abstract).
  • Miguel López Ripa, Iñigo J. Sola, Benjamín Alonso. Ultraestable spatiotemporal characterization of optical vortices in the visible and near infrared. TOM 13 Advances And Applications of Optics and Photonics – Oral contribution (Abstract). 
  • Rodrigo Martín Hernández, Luis Plaja, Carlos Hernández García. Fourier-limited attosecond pulse generation with magnetically pumped high-order harmonic generation. TOM 8 Non-linear and Quantum Optics – Oral contribution (Abstract)
  • Luis Plaja, Ana García Cabrera, Roberto Boyero-García, Óscar Zurrón, Julio San Román, Carlos Hernández García. Multi-beam vortex generation induced by the non-linear optical anisotropy of graphene. TOM 8 Non-linear and Quantum Optics – Poster (Abstract)
  • Victor W. Segundo Staels, Enrique Conejero Jarque, Daniel Carlson, Michaël Hemmer, Henry C. Kapteyn, Margaret M. Murnane, Julio San Román. Supercontinuum generation in the enhanced frequency chirp regime in multipass cells. TOM 8 Non-linear and Quantum Optics – Oral contribution (Abstract)
  • Carlos Hernández García. Novel ultrafast structured EUV/x-ray sources from nonlinear optics. TOM 13 Advances And Applications of Optics and Photonics – Oral contribution (Abstract). 
25 October, 2022 admin , , No comments
adminALF-USAL researchers participate in the annual meeting of the European Optical Society (EOSAM 2022)

OP Session – Relativistic Quantum Effects in Laser-Driven electrons

OP Session – Relativistic Quantum Effects in Laser-Driven electrons

Julio San Román, member of the Laser and Photonic Applications group (ALF-USAL), will give the seminar entitled “Relativistic quantum effects in laser-driven electrons” on October 21 at 1:00 p.m.

The seminar will be held in memory of Prof. Howard R. Reiss who passed away last August, and will take place in room VII of the Trilingual Building at the University of Salamanca.

19 October, 2022 admin No comments
adminOP Session – Relativistic Quantum Effects in Laser-Driven electrons

OP Session – Thermal and acoustic dynamics in complex materials by ultrafast techniques

OP Session – Thermal and acoustic dynamics in complex materials by ultrafast techniques

Begoña Abad Mayor, from the Nanophononics group at the University of Basel, will give the seminar entitled “Thermal and acoustic dynamics in complex materials by ultrafast techniques” on September 7 at 12:00.

The seminar will take place in classroom VII of the Edificio Trilingüe at the University of Salamanca.

5 September, 2022 admin No comments
adminOP Session – Thermal and acoustic dynamics in complex materials by ultrafast techniques

It was not everything perfect

It was not everything perfect
 
Nowadays, the high-order harmonic generation process is an extended useful tool for the study of femtosecond dynamics. Nevertheless, there are still many doubts regarding the electron behavior inside different types of mediums.
 
Recent studies in solid targets have revealed new scenarios with extraordinary electronic dynamics compared with atoms or molecules. The process in solids can be explain through a semiclassical point of view using the electron trajectory from the excitation until the recombination with its hole in real space; the so-called perfect recollisions. However, recent studies have confirmed that part of the high-order harmonic emissions comes from trajectories where the electron and hole do not overlap in real space; the so-called imperfect recollisions.
 
In this work, we demonstrate the existence of imperfect recollisions when the medium is a single-layer graphene, and the driving laser pulse is linearly polarized. Graphene, compared to other solids, presents a singular structure band with points where the valence and conduction band are in contact. Our study has a great relevance because until this moment there were studies only with finite-gap solids and huge Berry curvature or using a driving field with elliptical polarization. We truly believe that this work takes a new step in the full understanding of the ultrafast dynamics driven by intense laser pulses in solids.
 

More information at:

Boyero-García, Roberto, Ana García-Cabrera, Oscar Zurrón-Cifuentes, Carlos Hernández-García, y Luis Plaja. «Non-classical high harmonic generation in graphene driven by linearly-polarized laser pulses». Opt. Express 30, n.o 9 (abril de 2022): 15546-55. https://doi.org/10.1364/OE.452201.
29 July, 2022 admin , No comments
adminIt was not everything perfect

Castilla y León Televisión echoes the meeting of the expert committee of the ATTOSTRUCTURA project

Castilla y León Televisión echoes the meeting of the expert committee of the ATTOSTRUCTURA project

The television channel Castilla y León Television publishes on its website the news about the meeting of the expert council of the ATTOSTRUCTURA project.

You can read the press release and watch the video on their website.

27 July, 2022 admin , , No comments
adminCastilla y León Televisión echoes the meeting of the expert committee of the ATTOSTRUCTURA project