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ALF-USAL Participation in RNO2021 – Poster Session

Several members of the Group of Applications Laser and Photonics (ALF – USAL) present the results of their research in the Poster Sessions organized during the XIII National Meeting of Optics (RNO 2021) that is taking place virtually from November 22 to 24 of 2021.

The works presented are included below:

All the details of the congress can be consulted on its website. You can also follow the event through the Twitter account of the XIII National Optics Meeting and the hashtag #RNO2021.

Structuring XUV Vector-Vortex Beams via High Harmonic Generation

Authors: Alba de las Heras, Alok Kumar Pandey, Julio San Román, Javier Serrano, Elsa Baynard, Guillaume Dovillaire, Moana Pittman, Charles G. Durfee, Luis Plaja, Sophie Kazamias, Olivier Guilbaud, y Carlos HernándezGarcía

 

Abstract: Structured light in the short-wavelength regime is emerging as a paramount tool to explore ultrafast spin and electronic dynamics. In this work, we demonstrate experimentally and theoretically the up-conversion of Vector-Vortex Beams (VVB) from the IR to the XUV regime, introducing a unique configuration of XUV coherent radiation spatially structured in its polarization and phase. The build-up of high-order harmonic generation driven by VVB is governed by the conservation of the Pancharatnam topological charge, which considers the intertwined spin and orbital angular momentum properties. The selection rule results in harmonic VVB with a high topological charge and smooth propagation dynamics.

new post-compression scheme: nonlinear propagation in multipass cells.

Authors:  Victor Segundo-Staels, Enrique Conejero Jarque y Julio San Roman1. 

 

Abstract: The development of short, pulsed lasers has paved the way of new scientific disciplines such as the femtochemistry or the attoscience. There are several well-known schemes to generate extremely short pulses, such as the post-compression techniques. One of the most used post-compression methods consists of the spectral broadening of the pulse via its nonlinear propagation through a hollow-core capillary filled with a gas. The post-compressed pulse obtained, after passing a phase compensation stage, can reach the few- and even single-cycle regime. 

We have developed a numerical model to study the nonlinear propagation of a laser pulse in an MPC. It is based on the standard Split-Step Fourier scheme in 4 dimensions, namely 3 cartesian coordinates plus the time dimension, as done by M. Hanna and co-workers7. As usual, the nonlinearities are processed in the space-time domain and linear effects in the frequency domain.  Our code is written in MATLAB, employing some recent storage functions that allow us to work with big amounts of data. Normally we use a resolution grid of 128x128x512x𝑍 points, where 𝑍 is the propagation coordinate, which could be adjusted with adaptative steps based on the nonlinearity demands. With this precision we solve the propagation of tens of roundtrips in short amounts of time, which allows us to have bigger accuracy in transversal or temporal coordinates.  Currently, we are able to retrieve previous results from the literature of spectral broadening in MPCs. This will allow us to study the behaviour of MPCs in different scenarios and to study the role of other nonlinear terms that could be relevant in some situations. 

Generación de armónicos de orden elevado en presencia de campos magnéticos ultraintensos. 

Authors: Rodrigo Martín, Luis Plaja y Carlos Hernández – García. 

Abstract: El auge del estudio de haces de luz estructurados en los últimos años ha permitido demostrar nuevos esquemas en los procesos de interacción láser-materia. Un ejemplo son los haces de luz vectoriales con polarización azimutal, mostrando un campo magnético longitudinal oscilante a frecuencias ópticas. Estos campos magnéticos pueden llegar a ser del orden de giga-Tesla para intensidades máximas del haz vectorial en el rango de 10²¹ W/cm². En este trabajo se ha estudiado cómo estos campos magnéticos pueden afectar al proceso de generación de armónicos de orden elevado.  Hemos observado cómo los espectros mejoran de manera notable tanto en eficiencia como en la frecuencia máxima que puede llegar a generarse. Además hemos dado una explicación desde un punto de vista fundamental de la dinámica que sufre el electrón durante su excursión por el continuo bajo el efecto del campo magnético. Por un lado, se produce una reestructuración de los niveles del continuo de manera análoga a un hilo cuántico, debido al confinamiento transversal del campo magnético. Por otro lado, la función de onda del electrón, tras la fotoionización, sufre de una dinámica de revivals o sucesivas focalizaciones que permite entender el aumento de las eficiencias y las frecuencias máximas que pueden obtenerse. Este trabajo presenta un nuevo esquema de la interacción láser-materia con la nueva generación de láseres de petavatio actualmente en construcción.

Pressures gradients in the compression of few-cycle pulses in gas filled hollow-core fibers.

Authors: Marina Fernández Galan, Julio San Román y Enrique Conejero Jarque. 

 

Abstract: Gas-filled hollow-core fibers (HCFs) have been extensively used for generating intense ultrashort laser pulses, which are now essential tools in disciplines such as ultrafast spectroscopy or attosecond science. In this work, we have studied the generation of few-cycle pulses in HCF compressors with non-uniform pressure along the fiber. Varying the gas pressure, both dispersion and nonlinearity can be easily tuned, yielding output pulses with extremely short durations and a clean temporal profile.

Caracterización espacio temporal de vórtices ópticos ultracortos

Authors: Miguel López-Ripa, Íñigo Sola y Benjamín Alonso

 

Abstract: Las técnicas de caracterización espaciotemporal de pulsos ultracortos han ganado gran importancia a lo largo de las últimas décadas. En este trabajo hemos implementado un sistema de caracterización espaciotemporal compacto y ultraestable basado en interferometría por desplazamiento lateral en un montaje monolítico. Además, lo hemos empleado para caracterizar vórtices ópticos ultracortos generados usando láminas nanoestructuradas, demostrando su viabilidad y abriendo la puerta a explorar y optimizar nuevos casos de interés en aplicaciones de óptica ultrarrápida.

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The Lord of the Rings: the Graphene Match

As in the books of JRR Tolkien, the Research Group of Laser Applications and Photonics (ALF-USAL) continues their adventure in the search of the Ring.
 
After finding the Phase-Matched Ring in Argon based High-Harmonic Generation [1], now they’ve gone a step beyond to find the Phase-Matched Ring in graphene. It turns out that when a graphene layer is illuminated by an intense laser beam, ultrafast electronic dynamics result in the emission of higher frequency radiation.
 
This emission can be understood as a result of an excitation of electrons from the valence to the conduction band, a subsequent acceleration in such conduction band, and a final recombination with the holes that were left in the valence band. Such process, known as high-order harmonic generation, is very sensitive to the intensity of the incoming laser field, and thus to the spatial profile of the beam.
 
As a consequence, the radiation emitted from different parts of the graphene layer can interfere, both destructively or constructively. It turns out that an adequate matching between the emissions from different parts of the graphene layer is required to obtain bright high-frequency radiation.
 
In their latest work, the ALF-USAL group has demonstrated that when a graphene layer is illuminated by an intense Gaussian beam, the high-order harmonic emission is dominated by an annular region: the Phase-Matched Ring. This finding gives light into the macroscopic physics of high harmonic generation in graphene, offering a tool to engineer the process, and to increase its efficiency.
 
After finding the Phase-Matched Ring in Argon and in Graphene, the researchers of ALF-USAL group continue their adventures to rule intense light-matter interactions.
 

More information in: 

“Transverse phase matching of high-order harmonic generation in single-layer graphene”, Roberto Boyero-García, Óscar Zurrón-Cifuentes, Luis Plaja, and Carlos Hernández-García,  Optics Express 29, 2488-2500 (2021).

References:

[1] “Carrier-envelope-phase insensitivity in high-order harmonic generation driven by few-cycle laser pulses”, C. Hernández-García, W. Holgado, L. Plaja, B. Alonso, F. Silva, M. Miranda, H. Crespo, and I. J. Sola, Optics Express  23, 21497 (2015)

Download in Gredos@Universidad de Salamanca: http://hdl.handle.net/10366/146004

 
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XIII NATIONAL OPTICAL MEETING – ALF Participation

The National Meeting of Optics of the year 2021 (RNO2021) will take place next week from November 22 to 24. In this online event that has more than 240 registered people and 19 sponsors, more than 200 scientific contributions will be presented.

The National Meeting of Optics (RNO) is a triennial congress organized by the Spanish Society of Optics (SEDOPTICA), which has a long history of more than 30 years. An average of 200 professionals from different specialties of Optics and Photonics in Spain converge in each RNO and it is where the latest scientific and technological advances in this field are presented.

The XIII RNO 2021, organized this year by the SEDOPTICA Women, Optics and Photonics Area, aims to maintain the high quality standards of this conference, placing special emphasis on creating a parity and attractive congress for younger researchers.

Being one of the main events related to research in the field of optics and photonics, it is an essential appointment in the calendar of the members of the Laser and Photonics Applications Group.

This year, the Laser and Photonics Applications Group present the following contributions:

  • Oral Contribution:Dispersive wave emission at a fixed wavelength through parameter scaling” (#53), A. Crego, E. Conejero Jarque and J. San Roman. Wednesday 24th (15:00 h).
  • Oral: Contribution: «Ultrafast Talbot Spectroscopy», Ana García-Cabrera, Carlos Hernández-García y Luis Plaja. Wednesday 24th (15:00 h).
  • Poster:Caracterización espaciotemporal de vórtices ópticos ultracortos” (#127), Miguel López-Ripa, Íñigo J. Sola & Benjamín Alonso. Monday 22nd (17:30-18:30h) and Tuesday 23rd (17:00-18:00h)
  • Poster:Structuring XUV Vector-Vortex Beams via High Harmonic Generation“, (#71). Alba de las Heras, Alok Kumar Pandey, Julio San Román, Javier Serrano, Elsa Baynard, Guillaume Dovillaire, Moana Pittman, Charles G. Durfee, Luis Plaja, Sophie Kazamias, Olivier Guilbaud, and Carlos HernándezGarcía. Monday 22nd (17:30-18:30h) and Tuesday 23rd (17:00-18:00h)
  • Poster: «Pressure gradients in the compression of few-cycle pulses y gas-filled hollow-core fibers». Marina Fernández Galán, Julio San Román y Enrique Conejero Jarque. Monday 22nd (17:30-18:30h) and Tuesday 23rd (17:00-18:00h)
  • Poster: «Divulgación de la óptica en tiempos de pandemia: actividades online realizadas por la OSAL student chapter.» Ana García-Cabrera, Víctor W. Segundo-Staels, Javier Prada-Rodrigo, Daniel García Carracedo, Alba de las Heras y Laura Rego. Monday 22nd (17:30-18:30h) and Tuesday 23rd (17:00-18:00h)
  • Póster. «SEDOPTICAMOF: fomentando la igualdad de género«. Rosa Ana Pérez, Ana I. Gómez, Francesca Gallazzi, Beatriz Santamaria, Alba de las Heras, María Baralida Tomás, Verónica González, Martina Delgado, y María Viñas. Monday 22nd (17:30-18:30h) and Tuesday 23rd (17:00-18:00h)

In addition, several members of the GIR Laser and Photonics Applications participate in the following spaces within RNO2021:

  • Assembly of the Committee of Quantum Optics and Nonlinear Optics. Monday 22nd (19:30-20:30h). During this assembly, the new Board of Directors of the Committee will be elected. Carlos Hernández – Garcia and Alba de las Heras appear as members of the committee, as president and student member respectively.
  • Round table: Ibero-American Meeting of OPTICA chapters. Wednesday 24th (17:00- 18:00h)
  • RNO Young. Activity «Óptica sin limites«. Tuesday 23rd (14:05-14:55h) (Ana García Cabrera)
  • RNO Young. Activity «Conecta y LúZete«. Tuesday 23rd (14:55-16:00h) (Miguel López Ripa)

All the details of the congress can be consulted on its website. You can also follow the event through the Twitter account of the XIII National Optics Meeting and the hashtag #RNO2021.

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Optical nanotechnology using electrons.

In 1924,  Louis-Victor Pierre Raymond, pair of France  and Duke of Broglie, astonished his contemporaries in proposing that electrons behave as waves,  when moving along spatial dimensions of a few millionths of a milimeters. These distances, dubbed nanometers, remained technologically unaccessible until some decades ago. Roughly speaking, if the electrons appear as waves under these circumstances, we should expect their behaviour close to that of light. One of the most obvious manifestations of the wave nature of light is diffraction, the modification of its structure when passing through small slits. In 1836, the british physicist Henry Fox Talbot observed an extraordinary remarkable diffraction phenomenon: when light passes through a mask composed by a regular disposition of slits, it forms an image of the slits at some particular distances from the mask. This image if formed spontaneously, without he use of any focalizing element as lenses or mirrors. Our study predicts theoretically that this very same effect arises in the electron waves, if the electrons are detached from a periodic crystal due to the interaction with an electromagnetic field. The Talbot imaging effect would allow to control the shape of the electron wave and, therefore, some of the properties of their emission of light. Almost magically, the spatial structure of the Talbot image is codified in the temporal structure of the light emission. All this, of course, at nanometric scales!. More info at:  [1]

A. García-Cabrera, C. Hernández-García, and L. Plaja, Ultrafast Sub-Nanometer Matter-Wave Temporal Talbot Effect, New Journal of Physics 23, 093011 (2021).

Download in Gredos Universidad de Salamanca  http://hdl.handle.net/10366/147197

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Carlos Hernández, Young Scientist Prize In Atomic, Molecular and Optical Physics 2021

On June 8, the researcher Carlos Hernández García received the Young Scientist Prize In Atomic, Molecular and Optical Physics 2021 awarded by the International Union of Pure and Applied Physics (IUPAP) for his:

“…outstanding contributions to the theory and modeling of laser-driven high harmonic generation (HHG), both in high photon energy regimes, and in understanding how to manipulate the HHG waveforms to impart orbital and spin photon angular momentum, combining quantum simulations with laser Physics.”

You can read the press release published by iUPAP in this link and see the video that Carlos Hernández has recorded for the University of Salamanca where he talks about the main lines of research and activities of the Laser and Photonics Applications group, about the Attostructura project (ERC 851201) and the recent discoveries that have earned it this recognition.

Congratulations Carlos!

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Attostructura Seminar: imec’s AttoLab (Kevin Dorney) – Video

On November 12, Kevin Dorney, postdoctoral researcher and MSCA member of the AttoLab laboratory of imec (Interuniversity Microelectronics Center) in Leuven (Belgium) visited the Laser and Photonics Applications group as part of the activities planned in the ERC Attostructura project.

Kevin Dorney offered us the seminar entitled “Imec’s AttoLab: Bridging the Gap Between Fundamental Ultrafast EUV Science and Practical Metrologies for the Semiconductor Industry” in which he spoke of the laboratory that they have built in the imec facilities, the infrastructure that forms it and the techniques and capabilities they have.

You can see the video of the entire seminar on this page or on our YouTube channel.

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USAL4EXCELLENCE open call

First call for the USAL4EXCELLENCE project is now open. Until February 15, 2022, interested candidates may submit their applications through the procedure enabled in the electronic headquarters of the USAL

All the information about the project and the process of preparing / sending applications on the project website is available at the web: USAL4EXCELLENCE – USAL 4 Excellence

Application deadline: February 15th 2022

Project information

The “University of Salamanca Programme to Foster Research Excellence” (USAL4EXCELLENCE) is an initiative of the University of Salamanca (USAL) funded by the Horizon 2020 Programme under MSCA COFUND actions and cofunded by the Junta de Castilla y León, which aims to recruit 40 experienced researchers. Taking a ‘bottom-up’ approach, the overall objective of fellowships will be to recognise the brightest ideas and bring brilliant minds together.

 

USAL4EXCELLENCE will provide fellows with training and networking opportunities that will enhance their career development and leadership potential.

Fellowship conditions
  • Each fellowship will last 30 months, assuring proper project implementation.
  • Fellows will be hosted at USAL and they will have the opportunity and freedom to choose their destination for two secondments. Thus, fellows will have a mandatory period at USAL during the first 24 months (except for a voluntary secondment which should be started at least after 6 months at USAL), and a mandatory secondment during the last 6 months of the fellowship.
  • Fellows will be assigned a suitable supervisor and MENTOR.
  • USAL4EXCELLENCE will offer tailored support that will help fellows understand and adopt best practice in research. All fellows will be expected to attend relevant courses (on-line training, face-to-face training or events). Many of these courses will be delivered at a local level by departments, faculties and institutes, both as part of the USAL teaching programme and as standalone courses. All these courses will be available at this link.
Fellowship Requirements

BE EXPERIENCED RESEARCHERS (ERs)

It is mandatory to hold a Doctoral degree or at least four years’ full-time research experience by the time of the call deadline. No age and nationality restrictions will be applied.
 

COMPLY WITH THE STANDARD MSCA MOBILITY RULE

USAL4EXCELLENCE welcomes applicants from any nationalities but they may not have resided or carried out their main activity (work, studies, etc.) in Spain for more than 12 months in the 3 years immediately before the call deadline.
 

ENGLISH PROFICIENCY

All applicants must be proficient in English. Thus, they may upload a certificate of proficiency in English (minimum C1 level as measured by CEFR, Common European Framework of Reference for Languages) or, alternatively, they will have to demonstrate (only the 40 highest ranked candidates) their command over the English language through an English language proficiency test (which is not an official certificate) run by USAL Language Centre. Although candidates may opt for this second option, all selected applicants will be highly encouraged by USAL4EXCELLENCE Management Team to have available an official english certificate (minimum C1 level) before signing the contract.
Benefits

Upon signing the contract, the fellows will automatically be registered under the general regime of the Spanish Social Security System, which stipulates the following benefits

    • Full social health care coverage.
    • State pension.
    • Unemployment benefits.
    • Maternity/paternity leave of 16 weeks for women and for men according to Spanish law. When applicable, paternity leave could be joined indistinctly by the mother or the father, after week 7 from date birth.

The employment contract with USAL also specifies a series of specific benefits that might differ from other public administration positions:

  • Vacation: 22 working days per year.
  • Health Checks: all USAL employees have the option of a medical check every year, paid by USAL

Each fellowship includes funds for travel, reasonable research expenses as well as competitive salary. The total cost of a fellowship is 4.855 €/month and the net salary of the ER will be around 3.500 €/month. The net salary results from deducting all compulsory (employer/employee) Social Security contributions as well as direct taxes (e.g., income tax) from the gross amounts. Additionally, the remunerations may vary annually depending on the Social Security rates. The rate indicated above is for researchers working full-time

Interested candidates should follow the application process as defined in project web page.

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Attostructura Seminar: Imec’s AttoLab (Kevin Dorney)

Bridging the Gap Between Fundamental Ultrafast EUV Science and Practical Metrologies for the Semiconductor Industry

Next November 12 at 10:00 in classroom III of the Trilingual building, Kevin Dorney from imec will give the seminar: Imec’s AttoLab: Bridging the Gap Between Fundamental Ultrafast EUV Science and Practical Metrologies for the Semiconductor Industry

 High-harmonic generation (HHG) is nature’s most extreme nonlinear process known to date and, for just over 30 years, it has enabled the realization of table-top, short-pulsed extreme ultraviolet (EUV) and soft X-ray sources that are currently defining new paradigms in functional, nanoscale spectroscopy and imaging.

After decades of combined theoretical and experimental efforts, the underlying mechanism of gas-phase HHG is well understood and it is now known that the quantum physics behind the HHG process can be exploited to tailor the spectral, temporal, spatial, and angular momentum properties of the emitted short-wavelength light. In parallel, advancements in HHG system design have now resulted in robust, bright, and near turn-key systems for producing tunable, coherent EUV light for advanced metrology applications. In this light, imec has recently installed and commissioned the imec AttoLab, a first-of-its-kind, ultrafast, HHG-based EUV metrology and lithography lab with primary aims of performing high-NA EUV lithography and ultrafast materials characterization. 

In this talk, Dr. Kevin Dorney will give an overview of imec’s AttoLab, its infrastructure, and the current and foreseen ultrafast spectromicroscopies that will be deployed for characterization of novel semiconductor materials. In addition to spectroscopy and imaging capabilities, the lithographic capabilities of AttoLab will be presented, as well as the first interference lithography results obtained with a 13.5 nm, HHG-based EUV system. Finally, Dr. Kevin Dorney will give some perspectives and outlook on how HHG-based light sources can further benefit semiconductor metrology and lithography, in particular to the use of structured EUV light for advanced inspection and metrology of devices and materials. 

Seminar’s poster can be downloaded here.

The video of the seminar will be available on the Youtube account of the Laser and Fotonica Applications group once seminar ends.

Presenter bio

Kevin Dorney is a postdoctoral researcher and MSCA fellow in AttoLab at imec in Leuven, Belgium. He received B.S. degrees in Biology and Chemistry (2012) as well as an M.S. in Chemistry (2014) from Wright State University (Ohio, USA). In 2019, he earned a Ph.D. in Chemical Physics under the supervision of Profs. Margaret Murnane and Henry Kapteyn in JILA at the University of Colorado Boulder, specializing in the HHG-based generation of structured EUV beams with tailored spin and orbital angular momentum. His current research interests involve the deployment of bright, coherent 13.5 nm EUV light from HHG systems to investigate the ultrafast radiochemistry of the EUV exposure mechanism in photoresists, as well as their use in lithographic processes for resist screening and advanced metrologies to facilitate learning cycles as the semiconductor industry transitions to high-NA EUV lithography. 

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Physics students from the University of Zaragoza visit the ALF – USAL group (2021)

On October 21 and 22, the students of the Laser and Applications subject of the Physics degree at the University of Zaragoza together with their professor Sebastián Jarabo have visited our group to see first-hand the research that is being carried out and the operation of the equipment that is part of our laboratories.

You can see the photographs of the view in this gallery.

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OP Session – Studying the chemical composition of the university

María Teresa Belmonte from the University of Valladolid will give the seminar “Studying the chemical composition of the universe: what can spectroscopy do for astronomers” on October 20 at 12:15.

The seminar will take place in Classroom D2 of the Faculty of Sciences of the University of Salamanca.

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