A new scientific study titled “Laser 3D Micro-/Nano-Structurization of Luminescent Materials”, published in Advanced Optical Materials, presents exciting new findings. The research was led by scientists from the Institute of Electronic Structure and Laser (IESL – FORTH), Elmina Kabouraki, and Maria Farsari, in collaboration with Artūr Harnik, Greta Merkininkaitė, Dimitra Ladika, Arūnas Čiburys, Simas Šakirzanovas, and Mangirdas Malinauskas from Vilnius University.

Overview

The researchers explored various 3D printing techniques for microstructures, focusing particularly on luminescent materials used in applications like bioimaging, microlasers, and micro-LEDs. They noted that traditional manufacturing methods, such as monocrystal growth, tend to be expensive and time-consuming, often involving extensive post-processing. In contrast, laser direct writing was highlighted for its ability to significantly reduce both production time and costs. This method also enables two-photon polymerization, which improves the quality of 3D-printed structures and allows modification of the phosphors’ emission spectrum, thereby expanding their application range. Additionally, the researchers pointed out that laser writing can sometimes be used as a synthesis technique for new compounds. The review covered different 3D printing approaches, types of materials (organic, hybrid, and inorganic), and the fabrication of luminescent microstructures. It emphasized how laser direct writing and 3D lithography open new possibilities for both altering existing luminescent materials and creating novel ones. Overall, the study aimed to highlight successful 3D printing strategies and their potential outcomes, underscoring the innovative applications enabled by these advancements in luminescent materials.

Reference:  Harnik, A. et al. Laser 3D Micro-/Nano-Structurization of Luminescent Materials. Advanced Optical Materials (2025). https://doi.org/10.1002/adom.202500316 [1]

The groundbreaking research, titled “Emerging Ta4C3 and Mo2Ti2C3 MXene Nanosheets for Ultrafast Photonics,” published in Advanced Optical Materials, was carried out by scientists at the Institute of Electronic Structure and Laser (IESL – FORTH) - Michalis Stavrou, Maria Farsari, and David Gray - in collaboration with Benjamin Chacon, and Yury Gogotsi from Drexel University, as well as Anna Maria Pappa and Lucia Gemma Delogu from Khalifa University of Science and Technology.

Overview

The researchers found that Ta₄C₃Tₓ and Mo₂Ti₂C₃Tₓ MXenes exhibit exceptional ultrafast nonlinear optical (NLO) properties and carrier dynamics, as investigated using Z-scan and pump-probe optical Kerr effect techniques with femtosecond laser pulses in the visible and infrared ranges. They reported that the NLO responses of these materials surpass those of all previously studied MXenes and most other 2D nanomaterials, reaching remarkably high third-order susceptibility (χ⁽³⁾) values on the order of 10⁻¹³ esu. It was observed that Mo₂Ti₂C₃Tₓ demonstrated the strongest NLO response under both excitation regimes, which was attributed to charge transfer between the Mo and Ti layers in its structure. Under visible excitation, the MXenes showed pronounced saturable absorption, while under infrared excitation, they exhibited strong reverse saturable absorption, enabling effective optical limiting. Additionally, the pump-probe experiments revealed two distinct relaxation processes: a fast one occurring on the sub-picosecond timescale and a slower one a few picoseconds after photoexcitation. The researchers concluded that these MXenes rank among the most powerful NLO materials known, highlighting their significant potential for use in advanced photonic and optoelectronic applications, such as laser technologies, optical protection, telecommunications, and optical or quantum computing.

Reference: Stavrou, M. et al. Emerging Ta4C3 and Mo2Ti2C3 MXene Nanosheets for Ultrafast Photonics. Advanced Optical Materials 13 (2025). https://doi.org/10.1002/adom.202403277 [2]

The pioneering study titled “3D micro-devices for enhancing the lateral resolution in optical microscopy” conducted by researchers from the Institute of Electronic Structure and Laser (IESL – FORTH) - Gordon Zyla, Dimitra Ladika, Vasileia Melissinaki, and Maria Farsari - in collaboration with Göran Maconi, Anton Nolvi, Ari Salmi and Ivan Kassamakov from the University of Helsinki, as well as Jan Marx from Ruhr University Bochum, was selected as Outstanding Paper by Light: Advanced Manufacturing in 2024.

Overview

The researchers found that optical microscopy, while widely utilized, faces intrinsic limitations in lateral resolution due to light diffraction. To overcome this, they developed a novel 3D micro-device incorporating a dielectric micro-sphere, which is known to enhance resolution through photonic nanojets. They explained that their device consisted of a micro-sphere supported by a cantilever above a micro-hole in a modified coverslip, making it compatible with standard optical microscopes.

They reported using femtosecond laser ablation to create the micro-hole and multi-photon lithography to fabricate the micro-sphere and cantilever with high precision. According to their findings, a Zr-based hybrid photoresist enabled the creation of a nearly perfect micro-sphere with a surface roughness of λ/8. The team evaluated the performance of the micro-device using Mirau-type coherence scanning interferometry and white light illumination at 600 nm. They observed that the device significantly improved lateral resolution beyond the diffraction limit while preserving the axial resolution, as confirmed through calibration and simulations.

Reference: Gordon Zyla, Göran Maconi, Anton Nolvi, Jan Marx, Dimitra Ladika, Ari Salmi, Vasileia Melissinaki, Ivan Kassamakov, Maria Farsari. 3D micro-devices for enhancing the lateral resolution in optical microscopy[J]. Light: Advanced Manufacturing 5, 17(2024). doi: 10.37188/lam.2024.019 [3]

The theoretical and experimental study, titled "Double-Pulse Femtosecond Laser Fabrication of Highly Ordered Periodic Structures on Au Thin Films Enabling Low-Cost Plasmonic Applications," published in ACS Nano, showcases pioneering research carried out by scientists from the Institute of Electronic Structure and Laser (IESL) at FORTH - Fotis Fraggelakis, Panagiotis Lingos, George D. Tsibidis, and Emmanuel Stratakis - in collaboration with  Emma Cusworth, Nicholas Kay, Laura Fumagalli, Vasyl G. Kravets, and Alexander N. Grigorenko from Manchester University and Andrei V. Kabashin from Aix Marseille University.

Overview and Results

The researchers proposed a novel technique involving double femtosecond pulse (~170 fs) laser-assisted structuring to fabricate periodic plasmonic arrays on thin (~32 nm) gold films deposited on glass substrates. These arrays enable the excitation of surface lattice resonances (SLRs) or quasi-resonant features, which are highly valuable for biosensing and other applications. Traditional methods for producing such structures over large areas, such as electron beam lithography, are typically expensive and time-consuming, limiting their practical use.

In their study, the team demonstrated a single-step process that produces homogeneous and highly ordered laser-induced periodic surface structures (LIPSS) over large areas. Their experimental findings highlighted the critical role of the interpulse delay between the two laser pulses, identifying it as the key parameter that determines the uniformity and order of the resulting structures.

Theoretical modeling supported the experimental observations and provided important insights into the underlying mechanism of structure formation. Furthermore, ellipsometric measurements revealed that these LIPSS exhibit strong plasmonic behavior, including ultranarrow resonances linked to diffraction-coupled SLRs—features particularly important for biosensing and other applications.

Overall, the researchers demonstrated that femtosecond double-pulse laser structuring offers a promising, low-cost approach for large-scale fabrication of highly ordered and functional plasmonic structures.

Corresponding authors from IESL: Dr. Fotis Fraggelakis - Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology (FORTH),

Dr. Emmanuel Stratakis - Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology (FORTH) & Department of Physics, University of Crete

More details: https://doi.org/10.1021/acsnano.5c06177 [4]

The article "Unveiling asymmetric topological photonic states in anisotropic 2D perovskite microcavities", published in Light: Science & Applications, presents groundbreaking research conducted by scientists from the Institute of Electronic Structure and Laser (IESL) at FORTH — Emmanouil G. Mavrotsoupakis, Leonidas Mouchliadis, Minoas C. Chairetis and Apostolos Pantousas — in collaboration with Marios E. Triantafyllou-Rundell, Eleni C. P. Macropulos, and Constantinos C. Stoumpos from the University of Crete; Junhui Cao, Giannis G. Paschos, Alexey V. Kavokin, and Pavlos G. Savvidis (IESL’s Visiting Researcher) from Westlake University; Huaying Liu from Tongji University; and Hamid Ohadi from the University of St. Andrews.

From paper’s abstract:

“In this study, we explore a self-assembled two dimensional hybrid structure composed of anisotropically oriented organic/inorganic halide perovskite layers confined within a microcavity. The strong optical anisotropies of these perovskite systems, driven by significant refractive index contrasts and robust excitonic resonances at room temperature, enable the emergence of synthetic magnetic fields that mediate photonic and polaritonic interactions. The interplay between polarization-dependent modes and spatial inversion symmetry breaking gives rise to strong photonic Rashba-Dresselhaus spin-orbit coupling, leading to distinct modifications in band topology and energy dispersions. These effects result in the formation of unconventional topological features, including non-zero Berry curvature and off-axis diabolical points, within the photonic and polaritonic bands at room temperature.”

This study leverages the distinctive properties of halide perovskites— including their capacity to sustain room-temperature excitons and large birefringence —to contribute to the advancement of polaritonic platforms aimed at applications in topological photonics and spinoptronics.

Reference:

Mavrotsoupakis, E.G., Mouchliadis, L., Cao, J. et al. Unveiling asymmetric topological photonic states in anisotropic 2D perovskite microcavities. Light Sci Appl 14, 207 (2025). https://doi.org/10.1038/s41377-025-01852-8 [5]

“Attosecond metrology of VUV high-order harmonics generated in semiconductors via laser-dressed photoionization of alkali metals” was published in Nature Commun.

In an experimental and theoretical study published in Nature Commun.,16,1428 (2025), an international team of researchers from ELI-ALPS (Szeged, Hungary), ICFO (Barcelona, Spain) Guangdong Technion-Israel Institute of Technology (Guangdong, China), Technische Universität Wien (Vienna, Austria), Université de Bordeaux–CNRS–CEA (Bordeaux, France), and the Institute of Electronic structure and Laser at Foundation for Research and Technology-Hellas (IESL-FORTH), have demonstrated a scheme capable of generating and characterizing VUV attosecond pulses generated by laser driven semiconductor crystals. The study opens new spectral windows for attosecond science, enabling studies of bound-state dynamics in natural systems, while facilitating the generation of quantum light in the visible-VUV.

https://doi.org/10.1038/s41467-025-56759-0 [6]

Vacuum-ultraviolet attosecond pulses for tracing ultrafast processes of natural systems

A team of researchers has presented a new technique in Nature Communications capable of generating and characterizing vacuum-ultraviolet attosecond (10^-18 seconds) light pulses using laser driven semiconductors. With these pulses, the study of ultrafast dynamics in natural systems in all states of matter becomes possible.

Electrons in atoms interact with each other and with other particles, changing their motion, energies, and other features at incredibly fast timescales, on the order of attoseconds (10^-18 seconds). Capturing these ultrafast changes demands ultrafast light pulses. The pulse’s duration needs to be more or less the same as the effect’s; otherwise, it would be like trying to capture a hummingbird’s wing motion with a slow, long-exposure camera.

At the end of the XIX^th century, physicists thought that only femtosecond pulses (10^-15 seconds) were technically possible. That started to change in the late 1980s, when physicists linked high harmonic generation with attoscience. High harmonic generation (HHG) is a process that up converts low-frequency photons to higher frequencies, and what these researchers showed was that, when multiple harmonics are emitted, they can combine to form an attosecond pulse of light —something that was finally realized in 2001.

Attosecond science was born by generating and then employing extreme-ultraviolet (XUV) pulses, and as a consequence the methods developed to detect and characterize them focused in this frequency range. More than 20 years later, the creation of attosecond pulses to perform attoscience tasks remains XUV centered. Despite the many advances that XUV attosecond pulses have provided, they also pose a challenge. Most atoms, when hit by such an energetic light source, loose one or more electrons and become positively charged — a process known as ionization. But many worth studying processes in nature occur with non-ionized atoms, which remain in the so-called bound states. Since XUV light does not provide access to the bound states of the natural systems, their study has remained out of reach for attoscience. To address this, a source delivering less energetic attosecond pulses (for instance, in the vacuum-ultraviolet spectral range) and new methods to measure their main features (duration, intensity, etc.) are needed.

This has now been done by an international team of from ELI-ALPS (Szeged, Hungary), ICFO (Barcelona, Spain) Guangdong Technion-Israel Institute of Technology (Guangdong, China), Technische Universität Wien (Vienna, Austria), Université de Bordeaux–CNRS–CEA (Bordeaux, France), and the Institute of Electronic structure and Laser at Foundation for Research and Technology-Hellas (IESL-FORTH). For the first time, the team has demonstrated that semiconductors illuminated by strong mid-infrared laser light emit vacuum-ultraviolet (VUV) attosecond pulses, has retrieved the pulses’ temporal shape and has measured their total duration. These unprecedented results, published in Nature Communications [1], establish the basis of a novel technique for probing the ultrafast changes that occur in most natural systems, preserving their bound state rather than inducing their ionization.

These new tools and methodology could be used for conducting studies in natural systems, investigating their ultrafast dynamics and even possibly using them to engineer novel quantum light states.

Reference:

[1] A. Nayak, D. Rajak, B. Farkas, C. Granados, P. Stammer, J. Rivera-Dean, Th. Lamprou, K. Varju, Y. Mairesse, M. F. Ciappina, M. Lewenstein and P. Tzallas, Nature Commun., 16, 1428 (2025). (https://doi.org/10.1038/s41467-025-56759-0).

Η δημοσίευση των Ioannis Katsantonis (IESL post-doctoral fellow), Anna C. Tasolamprou (IESL's faculty member), Eleftherios N. Economou (Professor Emeritus), Thomas Koschny and Maria Kafesaki (IESL's faculty member) “Ultrathin, Dynamically Controllable Circularly Polarized Emission Laser Enabled by Resonant Chiral Metasurfaces, ACS Photonics, 12, 1, 71-78 (2025), https://pubs.acs.org/doi/10.1021/acsphotonics.4c01005?articleRef=control [7] επελέγη από τους Editors του ACS Photonics για  Cover του Volume 12, Issue 1, 15/1/2025.

From paper's abstract:

"This is a simple, low-cost, and ultracompact chiral resonant metasurface design, which, by strong local coupling to a quantum gain medium (quantum emitters), allows to implement an ultrathin metasurface laser, capable of generating tunable circularly polarized coherent lasing output. According to detailed numerical investigations, the lasing emission can be transformed from linear to circular and switch from right- to left-handed circularly polarized (CP) not only by altering the metasurface chiral response but also by changing the polarization of a linearly polarized pump wave, thus enabling dynamic lasing-polarization control."

Scientists at our institute have achieved a major advancement in gas sensing technology. By optimizing perovskite materials, they have created highly sensitive and stable ozone sensors that function effectively at room temperature. This research not only improves our ability to monitor environmental pollutants but also lays the foundation for developing advanced sensors for a variety of applications, contributing to a safer and more sustainable future.

This work is part of Dr Aikaterini Argyrou PhD Thesis, in collaboration with Mrs Rafaela Maria Giappa and Prof. Ioannis Remediakis from the University of Crete, Dr Emmanouil Gagaoudakis from IESL, and Prof. Vassilios Binas from Department of Chemistry, Aristotle University of Thessaloniki and IESL.

Corresponding authors from IESL: Drs Konstantinos Brintakis, Athanasia Kostopoulou, Emmanuel Stratakis

More details: https://doi.org/10.1002/smll.202404430 [8]

Dear friends and colleagues,
 

On behalf of IESL Scientific Council we welcome you to the 'IESL Science Days 2022' which will be held at the main amphitheater of FORTH on December 15-16, 2022. This is the second such meeting following the successful organization of the first one in 2019 aspiring to establish it as an IESL tradition.

Please find below the program of the meeting and the corresponding book of abstracts.
 

• [Science Days Program in PDF Format [9]]
• [Science Days Book of Abstract in PDF Format [10]]

Looking forward to seeing you all and having a fruitful event.

The Organizing Committee

Kiki Chrissopoulou and Petros Samartzis