We are pleased to announce the defense of the doctoral thesis of Ana García Cabrera, titled “Efectos de las simetrías del cristal en la generación de armónicos altos en grafeno.” The defense will take place on Monday, July 29th, at 11:00 in Aula III of the Edificio Trilingüe. The thesis directors are Dr. Luis Plaja Rustein and Dr. Carlos Hernández García.
We cordially invite you to attend this important presentation, as your presence and support will be greatly appreciated.
Zhensheng Tao from the State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (MOE) at Fudan University in Shanghai (P.R. China), will deliver a seminar titled “Solid-state High-order Sideband Spectroscopy and Microscopy” on July 23rd at 12:00 PM.
The seminar will take place in Classroom VII of the Trilingual Building at the University of Salamanca.
Abstract
Ultrafast manipulation of electronic states in quantum materials is essential for quantum-state engineering and ultrafast optical modulation. Recently, strong-field driven materials have exhibited fascinating tailored properties, including modification of topological states, modulation of optical properties and band-structure engineering. However, experimental methods for accessing the properties of strong-field dressed quantum states are lacking. In this talk, I will present our recently developed high-order sideband spectroscopy and microscopy techniques, which enables energy-, time- and space-resolved measurements on strong-field dressed quantum states or near-field wave phenomena. We present the first measurement on the dephasing rates of strong-field dressed exciton states, and resolve the strong-field exciton dissociation as the major dephasing mechanism. Furthermore, we realize the first 3D tomographic near-field tomographic imaging of a mid-infrared anapole resonant field in a micrometer-thick silicon resonator. These results highlight the high-order sideband spectroscopy and microscopy as a powerful tool for studying ultrafast manipulation of quantum materials.
Figure (a) Illustration of measuring the exciton dephasing rates using high-order sideband spectroscopy. (b) Illustration of imaging near-field distribution in dielectric optical resonators.
The collaboration between Ming-Chang Chen and the ALF group has a long history, dating back to 2016. As a result of this collaboration, several research articles have been published, thereby strengthening the bond between both institutions and significantly advancing the field of laser technology.
Prof. Chen established the ATTO-EUV lab in 2013 with the goal of generating bright and coherent EUV lasers on a tabletop. His recent research is dedicated to advancing laser technology and producing the shortest and brightest high-order harmonic EUV source. Notably, he pioneered and demonstrated the complete solution for controlling the polarization of isolated attosecond pulses and invented the broadband EUV polarimeter. By introducing the highly efficient post-compression technique, CASCADE, he enabled the production of single-cycle IR pulses and isolated attosecond EUV pulses. This accessible and reliable tabletop EUV light source has opened up numerous possibilities, including pioneering EUV spectroscopic ellipsometry and achieving the brightest EUV light source for nano-imaging.
Raoul Trines from STFC Rutherford Appleton Laboratory in Didcot (United Kingdom) will deliver the seminar titled “Laser Harmonic Generation: A Beat Wave on Steroids” on July 11th at 12:00 PM.
The seminar will take place in room VII of the Trilingual Building at the University of Salamanca.
The laser beat-wave concept was developed in the 1980s to generate waves in low-density plasma using dual-frequency lasers. In this process, sidebands are generated in the electromagnetic wave spectrum. In this talk, we show that the beat-wave concept can also be used to study laser harmonic generation for both Gaussian beams and higher-order laser modes (e.g., Laguerre-Gaussian).
We present a novel framework to study laser harmonic generation, considering it as a multi-dimensional beat-wave process [1]. This framework allows us to calculate and visualize harmonic progressions more easily. It also includes a specific way to simultaneously analyze the frequency, spin, and orbital angular momentum (OAM) content of the harmonic radiation, providing deeper insight into this process.
We will apply our framework to the interaction of laser pulses with structured targets and show that we can achieve tunable OAM spectra and frequency combs in this configuration. We will also use our methods to analyze harmonic generation in nonlinear optics involving higher-order phase and polarization topologies, thus demonstrating that our results have many applications beyond laser-solid interactions.
Top: Schematic illustrating the generation of higher order harmonics (blue: σ= 1; green: σ=−1) of an incoming CP pump pulse (red) in (a) reflection and (b) transmissive configurations, from a threefold structured target. Bottom: Expected 2D harmonic spectrum from: (c), a flat target driven by a LP pump pulse with ℓ= 1; (d) a target with a circular structure hit by a CP pump pulse of ℓ= 0; and (e), a target with a threefold structure hit by a CP pump pulse of ℓ= 0). The blue shaded area indicates the potential for a frequency comb at ℓ= 0
The ALF USAL group had a prominent participation in the XIV National Optics Meeting and the V National Young Optics Meeting (RNO2024) held from July 2 to 5 in Murcia, Spain.
This event, which brings together leading experts and young talents in the field of optics, has been an exceptional platform to present the latest advances in research and development in this field.
The group contributed with a series of works that address various areas of modern optics, standing out for their innovation and scientific rigor. The presented works are summarized below:
In addition to presenting their work, the researchers from the ALF USAL group also contributed to the conference by moderating several oral communication sessions:
These works reflect the ALF USAL group’s commitment to scientific excellence and their ability to lead in the field of optical research. The diversity and depth of their studies presented at RNO2024 underscore their crucial role in advancing modern optics.
Ming-Chang Chen from National Tsing Hua University in Hsinchu, Taiwan, will deliver the seminar titled “Advancements in Turn-Key Attosecond Light Sources and Their Application in Probing Spin Dynamics” next Wednesday, July 10th at 1:00 PM.
The seminar will take place in the basement classroom of the Trilingual Building at the University of Salamanca.
Prof. Chen established the ATTO-EUV lab in 2013 with the goal of generating bright, coherent tabletop EUV lasers. His recent research is dedicated to advancing laser technology and generating the shortest and brightest high-order harmonic EUV source. Notably, he pioneered and demonstrated the complete solution for the polarization control of isolated attosecond pulses and invented the broadband EUV polarimeter. Introducing the highly efficient post-compression technique, CASCADE, he enabled the production of one-cycle IR pulses and isolated attosecond EUV pulses. This accessible and reliable tabletop EUV light source has opened up numerous possibilities, including the first EUV spectroscopic ellipsometry and the brightest EUV light source for nano-imaging.
We are pleased to announce that three researchers from the Laser Applications and Photonics Group at the University of Salamanca have participated in the XVII Edition of the National Congress on Materials (CNMAT24). The congress took place from June 25 to 28, 2024, in the city of Málaga and brought together national and international experts in the field of materials.
Researchers Pablo Moreno Pedraz, Javier Rodríguez Vázquez de Aldana, and Ignacio López Quintás presented their latest work at this prestigious event, highlighting advancements and innovative applications in the field of photonics and laser technology.
The participation of our researchers in CNMAT24 not only reinforces our group’s position at the forefront of scientific research but also demonstrates our continuous commitment to excellence and innovation in the field of photonics and laser technology.
Congratulations to Pablo, Javier, and Ignacio for their outstanding contribution and for representing our group and the University of Salamanca so well at this important event!
The Seventh International Conference on Optical Angular Momentum (ICOAM 2024) is a prominent event in the field of optics and photonics, focusing on the study and applications of light’s angular momentum. This event gathers scientists and experts from around the world to discuss the latest advancements and share innovative research in areas such as particle manipulation, quantum optics, generation of angular momentum beams, and biomedical and communication applications.
The landscape of ultrafast structured light pulses has recently evolved thanks to the capability of high-order harmonic generation (HHG) to nonlinearly convert orbital angular momentum (OAM) from infrared to extreme-ultraviolet/soft X-rays. Up to now, HHG has been demonstrated to produce harmonic vortex pulses on the femtosecond scale through various studies, where higher-order harmonics exhibit distinct OAM content. This characteristic, a result of OAM conservation rules, has hindered the emission of vortex beams with attosecond pulse durations.
In this work, we demonstrate, both theoretically and experimentally, the generation of attosecond vortex pulse trains – a succession of light pulses each with a temporal duration of hundreds of attoseconds, and a similar helical wavefront. This achievement is realized by synthesizing a comb of high-order harmonics with identical OAM. To our knowledge, these are the first vortex pulses produced on the attosecond scale.
To achieve this, we drove HHG with an infrared bifurcated polarization tilt-angle grating, resulting from the non-collinear superposition of two counter-rotating circularly polarized beams with opposite OAM. The simultaneous conservation of linear momentum, spin angular momentum, and orbital angular momentum in the HHG process leads to two spatially-separated circularly polarized high-order harmonic beams with OAM independent of the order. Our work paves the way towards attosecond-resolved light-matter interactions at the natural timescale of electronic dynamics in atoms, molecules, or solids.
The generation of spatiotemporal optical vortices (STOVs) in the near-infrared regime has been successfully studied in recent years, both theoretically and experimentally. However, their extension to higher-frequency regimes has not yet been demonstrated. Over the last decade, it has been shown that high-order harmonic generation (HHG) can successfully transfer longitudinal optical vortices from the near-infrared to the extreme-ultraviolet (EUV) and X-ray regimes. Following an immediate analogy, one might think that HHG driven by STOVs would result in high-frequency STOVs with high topological charge. However, this scenario offers much richer possibilities.
In this work, we explore the nonlinear conversion of STOVs from the near-infrared to EUV/X-rays using HHG. Depending on the driving beam configuration, we identify two scenarios that lead to strongly differentiated phenomena.
Firstly, if HHG is driven by a canonical, elliptical, single-charged STOV focused on a gas target, high-frequency harmonic STOVs with the same topological charge as the driving field are generated. Our theoretical calculations unequivocally demonstrate that this result depends heavily on the non-perturbative nature of the HHG process. Thus, these results not only provide harmonic combs of low-topological charge STOVs in the EUV/X-ray range but also open the door to investigating some of the most fundamental questions about the intrinsic non-perturbative nature of the HHG process.
Secondly, if the driving beam is designed to deliver a canonical (elliptical), single-charged STOV at the gas target, high-order harmonic STOVs with high topological charge are generated. We demonstrate that in this scenario, the resulting topological charge of the harmonic STOVs increases according to the harmonic order multiplied by the fundamental topological charge, following the same well-known conversion rule as in longitudinal optical vortices.
Carlos Hernández García and Rodrigo Martín-Hernández’s participation in ICOAM 2024 underscores the Laser and Photonics Applications Group’s commitment to cutting-edge research and international collaboration in the field of optics and photonics. Their work not only contributes to the advancement of scientific knowledge but also opens new opportunities for innovative technological applications.
The research group ALF-USAL from the University of Salamanca is participating in the ATILA project, which focuses on developing new applications for biomedical implants. This project, led by AIDIMME and also involving the FIHGUV foundation, uses MELTIO’s metal 3D printing technology.
ALF-USAL is responsible for initial studies on the parameters needed to create models simulating the additive manufacturing process. These studies are crucial for improving implant biocompatibility and customization.
The project faces challenges in material precision and adaptability but has made significant progress in creating personalized, biocompatible implants.
For more details, visit the COPE press release.
On the occasion of the celebration on May 16 of the International Day of Light, the list of winners of the VI “Day of Light” Photographic Contest organized by the University Master in Physics and Laser Technology (USAL – UVA) in which the following entities and organizations also collaborate:
The complete ruling can be read on the website of the Master’s Degree in Laser Physics and Technology.
Below we include the 4 award-winning photographs.
1st Category: Light Technologies and Optical Phenomena.
Description: This photograph shows how the light from the stained glass windows coming from a rose window hits the columns in vibrant colors. It is striking how the light plays with cold and warm tones on the architectural elements.
Description: We have a photograph with a small flashlight through a diffraction grating. Thanks to this element, we are able to diffract the light and separate the different wavelengths that make up the light of the flashlight, being able to observe the different colors of the spectrum.
2nd Category: The Laser.
Description: Reflections of a laser with the inner walls of a glass beaker filled with oil. The glass is immersed in water, the laser is green and turns red as it passes through the oil.
Description: Image of the pattern formed when a laser beam hits a water jet.
Thank you very much to all the participants and congratulations to the winners.
