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.

Gallium fluoride-phosphate glasses are promising materials with wide optical transmission window, high volumetric density, and the ability to accommodate high concentrations of rare earth dopant ions within a tailored fluoride-rich coordination environment, resulting in high emission cross sections. In this work, the compositional system 25Ga(PO3)3-20ZnF2-30BaF2-(25-x-y)SrF2-xAgNO3-yNdF3 (x = 0-10 mol%, y = 0 or 1 mol%) was studied to understand how silver species affect the near-infrared (NIR) emission of Nd3+ ions, when the glasses are subjected to controlled heat treatment and to femtosecond direct laser writing (DLW). The glasses were obtained via the melt-quenching technique and characterized by DSC, XRD, UV-Vis-NIR absorption, and PL spectroscopy. The as-prepared glasses show broad UV-Vis excitation and emission bands arising from the coexistence of Ag+ ions and ionic Ag pairs. In samples with 10 mol% Ag+, brownish coloration and modified emission profiles indicated Ag nanoparticle formation at the surface. Heat treatment promoted the conversion of isolated Ag+ into ionic pairs, producing broadband emissions tunable by excitation wavelength and Ag+ concentration. In co-doped samples, Nd3+ introduced absorption dips in the Ag-related UV-Vis bands, consistent with energy transfer, which was further confirmed by shortened Ag excited-state lifetimes and increased Nd3+ NIR emission under UV-Vis excitation. In order to control the spatial distribution and size of Ag aggregates (nanoclusters, NCs) and to increase the energy transfer efficiency to Nd3+, femtosecond direct laser writing (DLW) was employed to co-doped glasses with 3 and 5 mol% Ag+. This approach enabled three-dimensional localized growth of Ag NCs with sub-micron spatial control. In the laser processed regions, the NIR emissions of Nd3+ at 900 and 1060 nm were significantly enhanced, clearly evidencing enhanced energy transfer from the localized laser-induced Ag-NCs to the Nd3+ ions. These findings suggest the possibility of tailoring high optical contrast near-IR emissions in glasses, enabling progress in advanced photonic applications.

Glasses based on the BaO-Ga2O3-GeO2 (BGG) system exhibit an excellent balance of thermal, physical, and mechanical properties, making them strong candidates for mid-infrared applications. Accordingly, this work presents a simple and robust approach for synthesizing BGG glasses with low hydroxyl content. Using a small amount of fluorine-based precursor (3 wt% NH4F–HF) as a dehydrating agent, the glass synthesis method under controlled atmosphere achieves a significant reduction of the OH absorption coefficient down to 0.03 cm−1 at 3 μm. In addition, the influence of residual fluorine on the glass properties is examined, providing deeper insight into the relationship between OH reduction and synthesis conditions. Overall, this study advances the understanding of hydroxyl removal in BGG glasses and establishes a reliable synthesis methodology with broad relevance for mid-infrared glass development and related fields.

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.

Transparent oxyfluoride glass-ceramics combining broad ultraviolet-to-mid-infrared transmission with enhanced rare-earth luminescence are promising materials for mid-infrared photonic applications. In this work, erbium-doped indium-germanate oxyfluoride glasses exhibiting good glass-forming ability under conventional melt-quenching conditions were synthesized and converted into transparent glass-ceramics through controlled heat treatment near the glass transition temperature. All compositions exhibit weak hydroxyl absorption (<0.3 cm(-1)) and wide optical transparency from the ultraviolet to the mid-infrared. Ceramization selectively induces the precipitation of SrF2 nanocrystals without significantly altering the glass transition temperature or refractive index. Structural analyses reveal uniformly distributed SrF2 nanocrystals with characteristic sizes below similar to 40 nm and suggest partial incorporation of Er3+ ions into fluorine-rich crystalline environments. Based on Vegard-law analysis of the X-ray diffraction lattice parameters using orthorhombic ErF3 (Pnma) as reference, the erbium concentration within the SrF2 nanocrystals is estimated to reach up to similar to 8 at.%. The associated visible transmission losses are attributed to Rayleigh scattering from the nanocrystalline domains. Spectroscopic measurements show that nanocrystallization modifies the local environment of Er3+ ions, leading to reduced inhomogeneous broadening, resolved Stark splitting, and enhanced emission intensity and lifetimes at both 1.5 and 2.7 & micro;m. In particular, part of the 2.7 & micro;m emission exhibits lifetimes extending from a few hundred microseconds in the precursor glass up to 1.77 ms in the glass-ceramics. The luminescence enhancement is attributed to the presence of fluorine-rich low-phonon-energy environments associated with the SrF2 nanocrystals, which reduce multiphonon relaxation rates. Time-resolved studies indicate the coexistence of two erbium environments in the glass-ceramics, corresponding to ions located in the oxide glass matrix and in fluorine-rich and/or crystalline surroundings. Despite crystalline fractions remaining below similar to 6.2%, millisecond-scale lifetime components reaching 1.77 ms are observed at 2.7 & micro;m, demonstrating that redistribution of only a small fraction of Er3+ ions toward fluorine-rich/crystalline environments is sufficient to induce pronounced changes in the luminescence response. These results demonstrate the effectiveness of controlled SrF2 nanocrystal precipitation for enhancing erbium luminescence and highlight the potential of this material system for 2.7 & micro;m erbium-doped mid-infrared fiber lasers.

The combination of microplasma generation and optical multi-material fiber technologies enables real-time diagnostics. The stack-and-draw technique has emerged as a promising method for creating multimaterial fibers suitable for plasma-based diagnostics. The elaboration of such devices for the generation of long-lasting microplasma for real-time and remote analyses remains challenging due to the difficulties of reaching long lengths without defects and with continuous electrodes. Post-functionalization of the electrode surface is also required to increase the plasma emission duration. In this study, glass was preferred over polymers for producing rectangular fibers (ribbons) that are easy to stack without wasting space and are resistant to high operating temperatures. Conversely, an aluminum alloy was chosen for the electrodes to reduce discontinuity defects. With the chosen bi-electrode geometry, the cooling rate during drawing has to remain between 200 and 300 °C/s to limit defect formation and guarantee low electrical resistivity. During plasma generation, an in situ oxide layer forms on the tip of each electrode. This results in a significant increase in plasma emission duration without the need for an additional post-functionalization step after drawing. These ribbons were tested in combination with an optical emission spectrometer to create a miniature gas detector for hydrocarbons.

Eu3+-doped sodium tantalum phosphate glass was synthesized by melt-quenching and its behavior under thermal poling/micropoling was investigated. The analysis of pristine glass indicates relatively high glass transition temperature (927 degrees C), refractive index (1.9) and transparency (similar to 80 %). The glass was thermally poled using homogeneous/microstructured electrodes under N-2, 250 degrees C and voltage of 900 V. Considering macro-poling, Maker Fringes measurements confirmed Second Harmonic Generation (SHG) in the poled glass attributed to Electric Field Induced Second Harmonic (EFISH) with a sodium depletion thickness of 1.7 mu m and chi((2)) value of 0.72 pm/V. SHG/Raman/Luminescence correlated microscopy measurements allowed identification of the structural changes within the poled layer corresponding to SHG active layer under the anode surface. Changes in the Eu3+-emission were also identified in the poled layer. Considering micropoling, microstructured electrode allowed microprinting of patterns on the glass. Atomic Force Microscopy measurements evidenced spatial reliefs of 90 nm depth and presence of edge effects between the poled and non-poled areas. Edge effect was also observed by SHG-microscopy on the surface of the sample. SHG depends on the polarization state of the incident radiation, indicating that thermal micropoling induces both longitudinal and in-plane static electric fields. These results suggest a microscale control of the optical properties on this sodium tantalum phosphate glass.

Ionizing irradiation was performed on barium–germanium–gallium (BGG) glasses using a 2.5 MeV electron beam. Through electron spin resonance spectroscopy, paramagnetic point defects, such as germanium- and gallium-related electron and hole trap centers, have been identified. The presence of silver in the BGG glass appears to hinder the stability of these defects at lower energy doses (104 Gy), with silver becoming the main trapping center. At higher energy doses (106 Gy), the glass undergoes structural modifications, hindering the trapping process of silver ions. Additionally, we evidence the importance of alkaline elements such as potassium and sodium on silver ions trapped centers’ formation.

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.

Terbium gallium garnet (TGG, Tb3Ga5O12) is an important material used as Faraday rotator in telecommunication, in interferometric facilities and in other important technological and photonic applications. TGG can be synthesized using different methodologies, however obtaining single crystals on a large scale is still a challenge. In this paper, for the first time, micrometric cubic single crystals were obtained from rare earths supersaturated melted heavy metal oxide glass compositions. A systematic study of the glass composition allied to the control of cooling parameters allowed the synthesis of micro-scale single crystals. A chemical route is proposed to isolate the crystals from the parent glass without compromising their properties. A series of structural and spectroscopic techniques was employed to characterize the crystals, which crystallize in the Ia 3 d space group. XRD, Raman and EDS measurements demonstrate the formation of the Tb3Ga5O12 crystalline phase and the microscopy images show the presence of microcrystals with a perfect cubic shape and size between 50 and 100 mu m. Luminescence analysis indicates a green emission between 530 and 560 nm characteristic of the 5D4 -> 7F5 transitions of Tb3+ ions and the presence of Stark components as well resolved multiplets and perfectly coherent with the Stark components of the TGG crystal. Finally, SQUID measurements were performed on glass samples containing crystals and on isolated crystals after removal of the glass and both presented paramagnetic behavior. The effective magnetic moment obtained for the TGG microcrystals between 50 and 70 mu m removed from the glass was 9.7 mu B, the same value as the theoretical effective magnetic moment for Tb3+ ions. This achievement represents an advance in the methodologies for obtaining TGG cubes in the micro-scale range, opening the possibility of mass production of such crystal and its uses in different technological photonic applications.

This study aims to design ceramic scaffolds for precise bone reconstruction using Powder Bed Laser Sintering (PBLS) to create cohesive Cu-doped HAp ribbons from a single lasered line on a thin powder bed atop a silicate lime substrate. Depending on laser parameters, two ribbon types—delaminated (CDR) or anchored (CAR)—are produced, both exhibiting surface density gradients from the center to the edges. Microscale analysis reveals surface density gradients in both ribbon types, extending from center to edge. CDRs also show depth-wise density variations, resulting in mechanical stresses that cause detachment and curling. In CARs, intense local heating and thermal conductivity cause a temperature rise beyond the irradiated area. The substrate acts as a thermal barrier, concentrating heat at the film-substrate interface and ensuring ribbon adhesion. Cracks propagate perpendicular to isothermal lines, enabling controlled crack patterning.

In barium gallo-germanate glasses, the extrinsic absorption losses from hydroxyl (-OH) groups are mostly due to the hygroscopic nature seen in the glass, its raw precursors and from the environment during the melting process. Their vibrations (harmonic or overtone) cause detrimental absorption bands in the infrared region which limit their use as host materials for rare-earth ions emitting in the infrared. It is therefore essential to minimize the concentration of (-OH) groups in the glass. Here, we present a dehydration method to prepare barium gallo-germanate glasses at high temperature (>1500 degrees C) under a controlled atmosphere (Ar-filled, with 0.1 ppm O-2 and 0.1 ppm H2O) with ammonium bi-fluoride (NH4F-HF) as dehydrating agent to lower (-OH)-based absorption coefficient down to 0.006 cm(-1) at 3300 nm wavelength. This improvement allows a significant lengthening of the lifetimes of the electronic transition in the near infrared at 1000 nm (I-4(11/2) -> I-4(15/2)) and 1537 nm (I-4(13/2) -> I-4(15/2)) in the glasses with ultra-low hydroxyl content due to reduced (-OH) quenching. This work paves the way for developing efficient barium gallo-germanate solid-state laser components for sensing operation in the near and mid-infrared spectral range (1-5 mu m).

The development of transparent glass-ceramics is a challenging endeavor in the field of mid-infrared photonics in order to fabricate robust and optically efficient materials. In this study, the glass-forming region of the novel xGeO2 - (100-x) (BaF2, SrF2, 1/2 In2O3) system is investigated, while SrF2-forming glass-ceramic compositions are identified. DSC measurements upon Eu2O3 doping show a decrease in the onset temperature of SrF2 crystallization. In the meantime, both XRD and TEM acquisitions confirm a decrease in crystal size as the dopant content increases. Part of the Eu3+ ions enter the SrF2 crystallites, as demonstrated by steady-state and time-resolved spectroscopies. Hence, we demonstrate that europium oxide doping enables a precise control of SrF2 nanocrystal size in the GeO2-BaF2-SrF2-In2O3 system. Our findings open doors towards the nanostructure tailoring of SrF2-containing germanate glass-ceramics using rare-earth dopants for luminescence and laser applications.

The mid-infrared (MIR) photonics market is rapidly expanding, driven by advancements in fiber-based MIR devices, particularly fiber lasers. However, the lack of robust MIR optical fibers remains a critical barrier to further technological progress. In this work, we present the fabrication of gallate glasses containing tantalum oxide, as it stands, the most robust mid-infrared glasses capable of being easily shaped into large bulk components, fibers or tapers. By introducing up to 20 mol

The development of miniaturized, remotely addressable sensing devices is crucial in a variety of fields, including healthcare, environmental monitoring, and security. This study introduces an optrode sensor comprising a multimaterial fiber composed of a phosphate glass cladding and a continuous Zn wire core, interfaced with a photoactive ZnO coating on its tip, deposited by anodization. It is shown that this optrode can promote photoelectrochemical reactions under illumination with UV light when immersed in an aqueous electrolyte. Proof-of-principle experiments demonstrate that these optrodes produce a glucose-responsive photocurrent, opening the way to biomedical applications. This optical sensor shows promise, as it would ultimately allow the decoupling of input stimuli, i.e., potential and light excitation, over a long distance. Due to its advantages in terms of integration, detection speed, and ease of use, these ZnO/Zn/phosphate optrodes hold significant potential for remote analysis and implantable sensors.

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].

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.

Second order nonlinear optical properties and structural rearrangements in GeO2-Na2O-Nb2O5 glasses were achieved by thermal poling. The effects of applied voltage as well as sodium and niobium contents on nonlinear optical (NLO)-active layer were investigated. Structural rearrangements in the anodic microlayer were investigated and occur due to sodium depletion promoting variation in bridging/non-bridging oxygen ratio and formation of a more polymerized network. Quantitative analysis of second harmonic generation signals confirm the electrooptical origin of the nonlinear optical response described by the electric-field-induced second harmonic model. chi(2) susceptibility values range from 0.42 to 0.76 pm/V depending on the niobium content. Lastly, the charge compensation mechanism with increasing applied voltage was described in detail. A progressive decrease in chi(2) for higher voltages was observed due to a greater poled thickness than expected by classical electrostatic models. In this case, the compensation mechanism occurs due to structural rearrangement, redox reactions, and motion of negative charges.

Glass system xTb(2)O(3)-40WO(3)-(60-x)B2O3, with x = 20; 22.5; 25 and 27.5 mol% were prepared by meltingquenching method. The samples were cut, polished and characterized by thermal, structural, optical, luminescent, magnetic and magneto -optical techniques aiming at applications in optical and magneto -optical devices. All terbium -containing samples exhibit magnetic response to neodymium magnets at room temperature. In addition, they feature thermal stability above 100(degrees)C, wide transparency in the visible and near infrared region. Magnetic susceptibility measurements revealed the paramagnetic character of the terbium, with high Curie constants and antiparallel spin alignment. An ascending pattern in the Verdet constant was discerned as the concentration of Tb2O3 increased, culminating in a measurement of -124 rad & sdot;T-1 & sdot;m(- 1 )at 632.8 nm for the sample containing 27.5 mol% Tb2O3. This value closely approximates those observed in terbium-borogermanates glasses and singlecrystal TGG, representing an alternative for the development of novel, cost-effective magneto -optical vitreous materials.