In this work, we demonstrate a one-step fabrication of microstructured ZnO surfaces via femtosecond laser irradiation of Zn metal immersed in ethanol. The process employs 200 kHz repetition rate pulses at a scanning speed of 1.36 mm s-1 and a line spacing of 1.7 & micro;m. The resulting surface morphologies, characterized by SEM and 3D optical profilometry, reveal a strong dependence on laser fluence. At lower pulse energies, micro-rippled surfaces with superwavelength laser-induced periodic surface structures (LIPSS) dominate the central regions, with a transition from low-to high-spatial-frequency LIPSS toward the periphery. At higher pulse energies, columnar structures prevail across most of the irradiated area, except at the edges where LIPSS reappear. Raman, photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS) analyses confirm that peripheral regions exhibit higher near-band-edge to defect emission ratios, indicating fewer oxygen vacancies, while central zones show stronger defect-related emission due to higher defect densities. XPS-derived O/Zn ratios corroborate this trend, with higher lattice oxygen content in less ablated areas. These findings reveal that femtosecond laser processing enables tunable defect engineering in ZnO, linking morphology and composition to spatial variations in optical properties.

Femtosecond lasers enable precise 3D nano- and micro-structuring in glasses, transforming photonic devices fabrication. The process relies on highly nonlinear interactions between femtosecond laser pulses and transparent materials, resulting in localized modifications of optical properties. In this article, we explore the fundamental mechanisms of laser-glass interactions, highlight advanced architectures for photonic integrated circuits, and discuss ongoing research aimed at expanding the range of achievable optical functionalities through innovative laser processing techniques and novel glass compositions.

Phosphate glass fibers are emerging as strong candidates for photonic applications due to their broad infrared transparency, compositional flexibility and multifunctional integration. Phosphates are good candidates for the development of sensors based on plasma discharge and optical emission spectroscopy in the visible and near infrared (NIR) regions. In this study, we explore the impact of Al2O3 and Ga2O3 modifiers on the structural, chemical and optical properties of phosphate glass systems, with a focus on their performance as multimode optical fibers. Bulk characterization shows that Ga2O3 increases density and refractive index, while Al2O = significantly improves hydrolytic durability. Optical losses were evaluated at 532, 633 and 976 nm for two drawn fibers, revealing that the Al2O3-based fiber exhibits lower losses at longer wavelengths (0.62 dB/m at 976 nm), while the Ga2O3-based fiber performs better in the green (0.74 dB/m at 532 nm). These behaviors were analyzed in relation to refractive index contrast, numerical aperture, modal dispersion and the impact of possible impurity absorption, particularly in the visible region. When benchmarked against literature data, the optical losses fall within a competitive range, validating the potential of these glasses for low-loss fiber applications. The results highlight the importance of carefully tailored glass chemistry and waveguide design to optimize performance across the visible and near-infrared spectrum. We further demonstrate the successful co-fibering of metallic Zn with phosphate core-cladding glasses, enabling multifunctional fiber architectures that may remain stable up to ∼400°C.

This paper investigates the laser induced breakdown spectroscopy (LIBS) signal enhancement mechanism provided by femtosecond laser microstructuring of copper samples. The surface morphology of such microstructured samples was characterized using confocal microscopy, scanning electron microscopy, and atomic force microscopy. Although little change was observed using confocal microscopy on the microstructures pre and post-LIBS laser shot, structures and particles in the sub-micrometer range were shown to partially melt on scanning electron microscopy images. This change was correlated with a sharp drop of the LIBS signal enhancement provided by a microstructured sample compared to a polished copper sample for successive LIBS shots on the same spot. Additionally, time resolved spectra revealed that the signal enhancement appeared after a delay of 100-800 ns. A physical model allowed demonstrating that such values of delay are compatible with the vaporization and ionization time of sub-micron spherical particles in the plasma, hence providing a delayed source of seed electrons responsible for the observed LIBS signal enhancement.

Optical microstructures imprinted in niobium germanate glasses by thermal poling were investigated by correlating Raman, phase contrast imaging, Second Harmonic Generation (SHG) and Atomic Force Microscopy (AFM) measurements. Structural characterizations by Raman microscopy have shown the presence of gradient in-plane poling effects. By varying the microscale anode designs, it has been observed that the difference between the size of the in-plane gradient poling effect and the pitch dimension of the electrode patterns can explain the refractive index contrast at the micrometer scale. SHG signals were localized in microregions located at the edges of the micropatterned anode electrode and the electro-optical origin of the second-order optical responses has been confirmed. Finally, the SHG responses of second-order optical diffraction gratings were studied. The observation of well-defined SHG optical diffraction peaks demonstrates the potential of these EFISH structuration in niobium germanate glasses for the development of nonlinear optical (NLO) micro-scale periodical designs. In this perspective, this paper demonstrated the implementation of NLO properties in germanate glasses containing a wide transmission window and promising for NLO photonic applications such as infrared wavelength conversion and electro-optical devices.

We report on femtosecond direct laser writing (FDLW) of single-mode optical waveguide supported by bismuth photochemistry in a zinc phosphate glass. Propagation attenuation of 2 dB.cm-1 at 976 nm was measured. The waveguide was written twice with 16 laser passes separated by 250 nm to make a square-like structure of 6 mu m x 6 mu m to perform a single-mode waveguide at 976 nm. The refractive index contrast of the waveguide was estimated to 1.5 x 10-3 by phase imaging microscopy. Hyper-spectral near-IR fluorescence confocal microscopy was performed to confirm the laser-induced valence change of Bi3+ to Bi+ ions, at the waveguide localization, demonstrating the FDLW creation of an integrated laser gain medium. Finally, a demonstration of waveguided laser amplification at 1345 nm is presented in and similar technologies, are reserved.

Practical work in optics is essential to understand complex abstract phenomena. Consequently, hands-on experiments are part of most physics’ curricula, despite the fact that they can be hard to set up and maintain. In this article, we present a virtual laboratory tool, called SHIRE, which allows students to carry out optical experiments from a desktop computer. SHIRE’s optic simulation is self-adaptive so that it allows the user to set up any optical assembly from scratch. The software includes pedagogical contents that facilitates autonomous work, and it also allows synchronous and asynchronous collaborative work. After a description of how this tool works, we present some examples of use as well as the opinions of the first users. We believe that this new digital tool can help transform current teaching practices in the teaching/learning of optics.

The rapid expansion of modern cities has significantly intensified heavy metal pollution in soil, the atmosphere, and particularly in aquatic environments, underscoring the urgent need for efficient pollutants detection methods [1]. Meanwhile, optical fibers, introduced nearly 40 years ago, are recognized as a cornerstone of innovation in sensing and instrumentation, driving remarkable progress in both academic and industrial research [2]. Recent progress in laser-assisted 3D printing technologies has further expanded the possibilities for a precise and dedicated patterning on fiber tips using polymer-based materials [3]. However, such materials may degrade under laser exposure. To overcome this limitation, hybrid organic-inorganic resins have been developed offering durable, cost-effective and eco-friendly solution to propose long-lasting structures [4].

Three-dimensional printing using two-photon polymerization (TPP), is nowadays a powerful technique for the fabrication of photonic components including optical waveguides. Numerous publications have demonstrated 3D printing of clad-less guiding structures in polymer materials [1], [2]. These waveguides, printed in a single step, result from a simple manufacturing method that has enabled advances and breakthroughs for the production of photonic integrated circuits (PICs). However, these waveguides have inherent losses related to the printing process, such losses predominantly resulting from scattering. A major cause of scattering losses arises from the surface roughness of the waveguide, which is detrimental to the quality of printed components by 3D TPP. In the case of femtosecond laser inscription in bulk glasses, the multi-laser-pass approach has already shown to homogenize the waveguide structure and thus to reduce the associated losses [3]. However, in 3D printing, few studies have referred yet on the multipass approach for the single-step direct printing of photonic structures. To produce coreclad waveguides, it is necessary to tune locally the index variation within the printed object. Recently, the ability to modify the laser power during the printing process has been demonstrated, referenced as (3+1)D multiphoton printing, leading to the realization of core-cladding waveguides and −6.2 dB.mm−1 losses [4].

This paper describes the optimization of femtosecond laser surface microstructuring of copper to obtain LIBS signal enhancement. Microstructures in the form of periodic rows are created on a copper sample with depths between 2 mu m and 24 mu m by tuning the femtosecond laser power, frequency, as well as the translation stage speed. A darkening effect is observed in the zones with microstructures, corresponding to a better light trapping effect than on a polished surface. The LIBS signal enhancement of the Cu I line at 521.8 nm is used as an indicator to select the type of microstructures which induces the maximum enhancement of the plasma emission. Characterizations of the microstructures through confocal microscopy and Time of Flight Secondary Ion Spectrometry are used to explain the change in signal enhancement between different microstructures. More specifically, deeper and darker microstructures are shown to provide less signal enhancement due to the higher content of copper oxide within the typical LIBS crater depth. A signal enhancement as high as 11 is obtained on the optimized microstructure. This enhancement is the result of a 70 % increase in electron density, 17 % increase in temperature and two times higher plasma lifetime. Finally, the resulting microstructured copper sample is used as a substrate for the LIBS analysis of a liquid. In this study, mineral water is dropped and dried on the substrate, and the LIBS signal of the Ca I lines intensities at 526.2 nm, 526.5 nm and 527.0 nm is found to be roughly four times higher than on the copper substrate without microstructures.

Integrated photonic devices are powerful tools, offering advantages for many applications as data & telecommunications, biosensing, quantum computing, 6G networks, HPC…. However, traditional fabrication methods are costly limiting their commercial use. Recent studies on 3D additive fabrication have demonstrated rapid and automated one-step production of optical passive devices (waveguides, couplers…), allowing new opportunities for large-scale, eco-friendly and flexible photonic sub-systems [1]. For that, different deposition techniques have been developed such as fused deposition modeling (FDM), inkjet printing, stereolithography (SLA), and two-photon polymerization (2PP). 2PP presents high lateral resolution (~ 100 nm) and enables to perform large-scale but time-consuming fabrication remains challenging. Ink-based printing methods provide a good balance between resolution and processing time [2].

We report on the pioneering inscription of Type-A volume Bragg gratings (VBGs) using the phase-mask technique and a high-power (100 W average power) femtosecond laser operating in burst mode. We manage 3D volume material processing while decoupling the thermal load with nonlinear interaction thanks to the independent tuning of inter-burst and repetition rates. Finally, an 850 × 900 × 500 µm3 grating was inscribed within 4.5 minutes, corresponding to a 4.1 mm3/h throughput and achieving ∼77% diffraction efficiency at 633 nm.

Direct laser-writing (DLW) is a well-known approach for creating photonic structures by locally modifying the refractive index of a material [1]. In recent decades, waveguides, splitters, selective filters, and more complex structures have been successfully demonstrated. Experiments on photo-thermo-refractive (PTR) glasses and laser-modified materials have revealed that the modulation of the refractive index is accompanied by a modulation of the third-order nonlinear properties, as demonstrated by various types of non-colinear third-harmonic generation (THG) [2]. This particular property arises from the strong correlation between the linear and non-linear indices [3].

The development of very-high-intensity femtosecond laser pulses in the 1980s has led to significant advancements in the field of laser micro/nanostructuring of materials [1]. The Direct Laser Writing (DLW) process, which involves creating 3D structures by focusing a laser beam within transparent materials, stands apart from UV photolithography due to its ability to shape complex three-dimensional geometries. However, the high surface roughness associated with this process prevents the achievement of optical-quality inscriptions.

Optical waveguides are key components in the development of next‐generation photonic circuits, where minimizing propagation losses remains a critical challenge. In this work, an innovative methodology is presented for the fabrication of core–clad waveguides using 3D printing based on femtosecond laser two‐photon polymerization and the hybrid Ormocomp resin. The approach leverages multiple laser passes and power modulation to locally tailor the refractive index of the printed structures. To assess the degree of polymerization and its effect on refractive index modulation, in‐depth Raman spectroscopic analyses are performed. These investigations provide insight into the molecular structure of the polymer and its correlation with optical index changes. Furthermore, several low‐loss core–clad waveguides with refractive index variations achieve through 2 to 6 laser passes are demonstrated. Optical characterization and interface roughness analysis reveal propagation losses as low as 0.16 dB·cm −1 , along with a minimum surface roughness of 28 nm. By combining original 3D printing techniques with detailed spectroscopic analysis and optical characterizations, this work paves the way for new possibilities for the additive manufacturing of integrated photonic waveguiding devices.

Three-dimensional (3D) microstructures were written by femtosecond (fs) laser aiming to manufacture waveguides inside niobium germanate glasses. The laser-induced damage threshold using 1030 nm fs-laser irradiation was investigated, and the waveguides were written in different fluences. The morphology, structural information and refractive index changes of microstructures were discussed. The waveguide cross-section microscopy data shows an elliptical shape with a diameter varying with the applied pulse energy. The micro-Raman maps demonstrate the occurrence of structural modifications with different microregions along the laser propagation direction. The refractive index profiles point to the formation of at least one microregion containing a positive refractive index change along the laser propagation. Guided light transmission measurements demonstrate the formation of single-mode waveguides inscribed at low pulse energy (up to 132 nJ) and an emitting waveguide in the rare-earth-doped sample. The visible luminescent response of erbium ions in the waveguide output was demonstrated and supports the possibility of using these core waveguides for future 3D multi-functional photonic devices operating in the visible region.

We have demonstrated the co-doping of silver ions and Bi3+ in glass allowing creation of 3D structures with tuning luminescence properties from the visible to the near IR with fs DWL. The tunable luminescence arises from the fs laser triggering both the photochemistry of silver ions and the photo-redox reaction of Bi3+ forming low valence Bismuth ions (Bi2+ red emitter and Bi+ near IR emitter). Confocal hyper-spectral lifetime-resolved imaging revealed the shortening of the fluorescence lifetime of silver clusters in the presence of Bismuth revealing the energy transfer mechanism from silver clusters to Bi+.

The tunable fluorescence property from the visible to near-infrared (NIR) region of high-localized 3D architecture down to the diffraction limit thanks to femtosecond (fs) Direct Laser Writing (DLW) in bismuth-doped, silver-containing glass is performed. Absorption and photoluminescent spectroscopy showed evidence of the homogeneous dispersion of bismuth ions (Bi3+) and silver ions in the glass matrix before DLW. High repetition rate fs DLW simultaneously inducing the photochemistry of silver ions and the photoredox reaction of bismuth ions has been obtained. Femtosecond DLW allows the creation of 3D fluorescence patterns formed by colocalization of a silver cluster and low valence bismuth ions, exhibiting an emission band covering the whole visible to the NIR wave range. The phenomena of electron transfer from silver atoms to bismuth ions and the nonradiative energy transfer from silver clusters to NIR-emitting bismuth ions are demonstrated.

HOBIT, which stands for "Hybrid Optical Bench for Innovative Teaching and learning" is an educational platform that leverages the combination of numerical simulation and physical manipulation to facilitate learning of complex phenomena and motivate users about wave optics in practical work. HOBIT operates in real time and is self-adaptive, providing realistic displays of optical phenomena with virtual augmentations designed to facilitate their understanding. HOBIT makes it quick and easy to build any reconfigurable optical experiment. Students can manipulate optical components and observe the changes induced on detectors and displays. We detail the technology, the simulation model and the initial teaching aids. Current and future enhancements should meet the needs of students at different levels, from high school to higher education degrees.