Category: Post_Eng

Post_Eng

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 Press release No comments

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 OP Session No comments

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 ALF results, Events and congress, Scientific outreach No comments

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 OP Session No comments

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 OP Session No comments

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 ALF results, Review No comments

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 Attostructura_En, Press release, Scientific outreach No comments

Meeting in Salamanca of the Scientific Advisory Committee of ATTOSTRUCTURA project

Next August will be thirty months since the ATTOSTRUCTURA project began, which means that half of its duration has already elapsed.

For this reason, the first meeting of the project’s scientific advisory committee has been held. The committee, made up of external researchers who are experts in the different fields of the project, has the objective of evaluating the development of the project, the results obtained to date and, if necessary, proposing changes or modifications in the lines of research. In this way, it is intended to ensure that the project achieves the best possible results while maintaining the highest level of excellence.

The members of the scientific advisory committee are:

Prof. Jon Marangos (chairman) – Imperial College (London, UK)
Dra. Alicia Palacios – Universidad Autónoma de Madrid (Madrid, Spain)
Prof. Misha Ivanov – Instituto Max Born de Óptica No Lineal y Espectroscopía de Pulso Corto en la Asociación de Investigación de Berlín (Berlin, Germany)
Catedrático Jamal Berakdar – Instituto de Física, Universidad Martin-Luther (Halle – Wittenberg, Germany)

The meeting, which took place on Friday, July 22, in the Board Room of the Faculty of Sciences, began with an open-door session in which the status of the project and the main results obtained to date were presented. The videos of that session will be available on the project website.

On the occasion of the meeting, Carlos Hernández García (principal investigator of the project) speaks in this video recorded by the audiovisual services of the University of Salamanca, about the project, its objectives and the results obtained.

#InvestigadoresDeLaUSAL | Carlos Hernández, investigador del GIR Aplicaciones de los Láseres y Fotónica de la USAL (@OpticaExtrema), explica en qué consiste el proyecto europeo ATTOSTRUCTURA, financiado por el @ERC_Research. pic.twitter.com/pKgAX1kF6E

— Universidad de Salamanca (@usal) July 25, 2022

25 July, 2022 admin ALF results, Attostructura_En, Scientific outreach No comments

ALF-USAL researchers participate in the XXXVIII Biennial Meeting of the Royal Spanish Society of Physics (Murcia)

From July 11 to 15, the XXXVIII Biennial Meeting of the Royal Spanish Society of Physics was held. The Laser and Photonics Applications group (ALF – USAL) has participated in said biennial, presenting some of the most recent results of the research it is currently carrying out.

The works presented were:

Luis Sánchez-Tejerina, Rodrigo Martín-Hernández, Rocío Yanes, Luis Plaja, Luis López-Díaz, Carlos Hernández-García. “Magnetic order excitation by magnetic fields from sub-picosecond structured laser pulses”. S15 Novel frontiers and challenges in magnetism – Oral contribution. (Abstract)
Rodrigo Martín-Hernández, Luis Sánchez-Tejerina, Enrique Conejero Jarque, Luis Plaja , Carlos Hernández-García. “Spatial isolation of femtosecond magnetic needles driven by azimuthally-polarized laser beams“, S15 Novel frontiers and challenges in magnetism – Oral contribution. (Abstract). Prize for the best oral contribution in the Symposium “Novel Frontiers and Challenges in Magnetism” awarded by the Spanish chapter of IEEE Magnetics.
Miguel López-Ripa, Íñigo J. Sola, Benjamín Alonso. “In-line and ultraestable spatiotemporal characterization of constant and time-varying optical vortices“, S9 Quantum Optics and Nonlinear Optics – Oral contribution (Abstract)
V. W. Segundo Staels, E. Conejero Jarque, J. San Roman. “Use of gas-filled multipass cells to generate clean supercontinuum spectra“, S9 Quantum Optics and Nonlinear Optics – Oral contribution. (Abstract)
Luis Sánchez-Tejerina, Rodrigo Martín-Hernández, Rocío Yanes, Luis Plaja, Luis López-Díaz, Carlos Hernández-García. “Non-linear, purely magnetic magnetization response to femtosecond structured laser pulses“, S9 Quantum Optics and Nonlinear Optics – Oral contribution. (Abstract)
Rodrigo Martín-Hernández,Luis Plaja, Carlos Hernández-García. “Magnetically-pumped High Harmonic Generation with circularly polarized driving fields”, S9 Quantum Optics and Nonlinear Optics – Oral contribution. (Abstract)
Ana García-Cabrera, Roberto Boyero-García, Óscar Zurrón Cifuentes, Julio San Román, Carlos Hernández-García, Luis Plaja. “Multi-vortex high-harmonic beams from graphene’s anisotropy“, S9 Quantum Optics and Nonlinear Optics – Oral contribution. (Abstract)
Alba de las Heras, Alok Kumar Pandey, Julio San Román, Javier Serrano, Luis Plaja. “Extreme-ultraviolet scalar and vectorial vortices with very high topological charge“, S9 Quantum Optics and Nonlinear Optics – Oral contributionl. (Abstract). Winner of the “Young Researchers” contest in the student category.
Ignacio Lopez-Quintas, Warein Holgado, Rokas Drevinskas, Peter G. Kazansky, Íñigo J. Sola, Benjamín Alonso. “Collinear optical vortices with tailored topological charge generated by angular momentum transfer“, S9 Quantum Optics and Nonlinear Optics – Poster. (Abstract)
Javier Serrano, Carlos Hernández-García. “High-performance simulations of high-order harmonic generation based on artificial intelligence“, S9 Quantum Optics and Nonlinear Optics – Poster. (Abstract)
Rosa Ana Pérez-Herrera, Alba de las Heras, María-Baralida Tomás, Beatriz Santamaría, Clara Benedí-García, Ana I. Gómez-Varela, Verónica González-Fernández, Martina Delgado-Pinar. “The future researchers in Optics and Photonics: gender bias in the PhD theses defended in Spain in 2015-2020“, S2 Women in Physics – Oral contribution. (Abstract).

In addition, Carlos Hernández García participated in the organization of the congress as part of the scientific committee.

25 July, 2022 admin ALF results, Awards and honours, Events and congress, Scientific outreach No comments

OP Session – Reservoir Computing with Quantum Systems

Rodrigo Martínez, from the Instituto de Fisica Interdisciplinar y Sistemas Complejos (IFISC), will give the seminar entitled “Reservoir Computing with Quantum Systems” on June 09 at 12:00 a.m.

The seminar will take place in Classroom IV of the Edificio Trilingüe, University of Salamanca.

31 May, 2022 admin OP Session No comments