Category: OP Session

OP Session

OP SESSION – SOLID-STATE HIGH-ORDER SIDEBAND SPECTROSCOPY AND MICROSCOPY

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.

16 July, 2024 admin OP Session No comments

OP SESSION – Laser harmonic generation: a beat wave on steroids

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.

Summary:

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.

[1] R. Trines et al., “Laser harmonic generation with independent control of frequency and orbital angular momentum”, Nature Communications, in press (2024), https://doi.org/10.21203/rs.3.rs-3458883/v1

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

11 July, 2024 admin OP Session No comments

OP Session – Advancements in Turn-Key Attosecond Light Sources and Their Application in Probing Spin Dynamics

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.

Abstract:

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.

2 July, 2024 admin OP Session No comments

OP SESSION – Heat Transfer Mechanisms in Nanoscale Materials

Rosa Pilar Merchán Corral, a colleague from the Laser and Photonics Applications Group, will give a seminar titled “Heat Transfer Mechanisms in Nanoscale Materials” on June 17 at 12:30 PM.

The seminar will take place in classroom VI of the Trilingual Building at the University of Salamanca.

In this talk, a brief review of main heat equations will be presented, starting with the classical Fourier’s law and advancing into the Maxwell-Cattaneo-Vernotte and Guyer-Krumhansl equations. Furthermore, key heat conduction regimes (diffusive, hydrodynamic, ballistic) in nano-scale materials will be analysed. Finally, a possible experimental setup in semiconductors will be shown, along with some current studies and their key outcomes.

13 June, 2024 admin ALF results, OP Session No comments

OP Session – Novel ultrafast sources for attosecond spectroscopy

Rocío Borrego Varillas from the Institute of Photonics and Nanotechnology at the National Research Council will give a seminar titled “Novel ultrafast sources for attosecond spectroscopy” on June 11th at 12:30 PM.

The seminar will take place in Room VII of the Trilingual Building at the University of Salamanca.

5 June, 2024 admin OP Session No comments

OP Session – Random Lasers: Controlling their spectra persistence

Pedro Moronta from the Instituto de Ciencias Materiales de Madrid (ICMM), will give the seminar entitled “Random lasers: controlling their spectral persistence” on Friday, March 22 at 13:00.

The seminar will take place in room II of Edificio Trilingüe at Universidad de Salamanca.

19 March, 2024 admin OP Session No comments

OP Session – Polarization controlled orbital angular momentum operations in nonlinear wave mixing

Antonio Zelaquett Koury from the Fluminense Federal University in Brazil, will give the seminar entitled “Polarization controlled orbital angular momentum operations in nonlinear wave mixing” on January 17 at 12:30.0.

The seminar will take place in room VII of Edificio Trilingüe at Universidad de Salamanca.

Abstract: We investigate nonlinear wave mixing processes induced by transversely structured light beams. The interplay between different photonic degrees of freedom determines the structure of the fields generated by the nonlinear processes. In birefringent media, the nonlinear interaction can be directly affected by the polarization of the interacting beams. For example, in Type-II second harmonic generation, this interplay allows for polarization-controlled switching between different orbital angular momentum (OAM) operations. It can also be used for spin-to-orbital angular momentum transfer. Moreover, either in birefringent or isotropic media, a less intuitive interplay occurs between radial and angular degrees of freedom of paraxial modes undergoing nonlinear propagation. This radial-angular coupling leads to interesting chiral relationships that will be discussed.

9 January, 2024 admin OP Session No comments

OP Session – Otra forma de mirar. Una nueva línea de investigación en Microscopía No Lineal

Ignacio López Quintás from the research group in Laser Applications and Photonics (ALF) will give the seminar titled “Otra forma de mirar. Una nueva línea de investigación en Microscopía No Lineal” on December 18 at 1:00 p.m.

The seminar will take place in classroom VII of the Trilingual Building at the University of Salamanca.

Abstract: El desarrollo de la microscopía siempre ha buscado nuevas formas de observar la naturaleza para obtener información sobre objetos cada vez más pequeños. En esa búsqueda, surge la microscopía no lineal, que gracias al desarrollo de los pulsos láser ultracortos y ultraintensos permite observar la materia de una forma distinta. Esta técnica, gracias a su carácter confocal, permite estudiar muestras con una alta resolución espacial y proporciona información muy valiosa en campos como la biología. En el Grupo de Investigación en Aplicaciones del Láser y Fotónica de la USAL, hemos desarrollado recientemente una nueva línea de investigación basada en la microscopía no lineal. En esta charla se presentarán los conceptos básicos de esta técnica y los avances en el desarrollo de un microscopio no lineal construido íntegramente en nuestro laboratorio, así como los primeros resultados aplicados al estudio del microprocesado láser en cristales de gran interés en el campo de la Óptica

11 December, 2023 admin OP Session No comments

OP Session – Theoretical advances in structured light with longitudinal and transverse orbital angular momentum

Miguel Ángel Porras from the Polytechnic University of Madrid will give the seminar titled “Theoretical advances in structured light with longitudinal and transverse orbital angular momentum” on November 29 at 1:00 p.m.

The seminar will take place in classroom IV of the Trilingual Building at the University of Salamanca.

Abstract: The control of ultrafast and strong field processes using structured light with orbital angular momentum (OAM) requires the most detailed knowledge of the physical properties of these light waves, and in particular, the amount of OAM carried by them and their propagation dynamics. While experiments of high harmonic and attosecond pulse generation with longitudinal OAM are made routinely in diverse experimental configurations, it is not yet completely clear the limits of the amount of OAM that the driving pulses can carry. Also, numerical studies of second and higher order harmonic generation using pulses with transverse OAM are being conducted, and experiments are planned, but at present there is a lack of knowledge about their propagation properties, and a hot debate on the amount of transverse OAM they carry, and hence transfer to the harmonics. In this talk recent theoretical developments aimed at clarifying these issues will be exposed.

24 November, 2023 admin OP Session No comments

OP Session – Tailoring Light’s Polarization for Chiral Discrimination

Laura Rego from the Chemistry Department of the Autonomous University of Madrid, will give the seminar titled “Tailoring Light’s Polarization for Chiral Discrimination” on November 24 at 1:00 p.m.

The seminar will take place in room VII of the Trilingual Building at the University of Salamanca

Abstract: Chiral molecules are very relevant in many chemical and biological processes. For that reason, distinguishing between the two versions of a chiral molecule (enantiomers) is vital, but it is also challenging. In this talk, we will see several schemes to study chirality using ultrashort laser pulses with structured polarization. Our methods take advantage of light’s tailored polarization to create enantiosensitive interferences in the non-linear optical emission from the chiral molecules. First, we will show how to turn an ultrashort elliptical pulse into an efficient chiro-optical tool: by tilting its polarization plane towards its propagation direction. Second, we will introduce a different approach for efficient chiral recognition which relies on the interference between two low-order nonlinear processes: sum-frequency generation and third-harmonic generation. Finally, we will see how we can imprint chirality in atoms. In these theoretical proposals, the molecular handedness can be retrieved by all-optical measurements and in ultrafast time scales.

21 November, 2023 admin OP Session No comments