Chalcogenide Glasses Research Articles

Ultrafast-laser-inscribed multiscan type-I mid-infrared waveguides and beamsplitters in IG2.

This study reports the fabrication and characterization of various configurations of mid-infrared waveguides and beamsplitters within the chalcogenide glass IG2 using ultrafast laser inscription (ULI). Our investigation reveals two distinct regimes of ULI modification: weak and strong. The strong regime, marked by higher pulse energies, presents darker and prominent waveguide morphology, enabling efficient light guiding at 4.55 µm, but with higher scattering losses at shorter wavelengths. In the weak regime, we observed a significant enhancement in the mode confinement and a reduction in the propagation loss within the multilayer structures. We have investigated key geometric and inscription parameters such as inscription pulse energy and number of layers, as well as arm separation and splitting angles for beamsplitters. We have successfully fabricated beamsplitters with configurations ranging from 1 × 2 to 1 × 8, achieving a uniform splitting ratio over 96% and a splitting loss as low as 0.4 dB at 4.55 µm. These findings highlight the significant potential of ULI-based IG2 waveguides and beamsplitters for mid-infrared photonics.

A thermo-physical study of In additive Se–Te chalcogenide glasses

A thermo-physical study of In additive Se–Te chalcogenide glasses

Measurement of Complex DC Kerr Coefficient of Chalcogenide Glasses by Electric Birefringence

Measurement of Complex DC Kerr Coefficient of Chalcogenide Glasses by Electric Birefringence

Impact of micro-indentation load/time and Zinc concentration on the thermo- mechanical characteristics of amorphous Se78Te20Sn2 alloy

We have performed hardness measurement experiments under different loads and loading times by performing micro-indentation marks in the present work. Chalcogenide glasses (ChGs) comprising Se78Te20Sn2 and Se78-xTe20Sn2Znx (where x = 0, 2, 4, & 6) alloys are the subject of micro-indentation tests in this work. We have utilized both micro-indentation and optical microscopic methods to determine Vickers hardness. Thermal glass transition phenomena have been identified through DSC techniques. The modulus of elasticity (E), an essential mechanical property, has been evaluated using established empirical equations. Further, we have studied other mechanical parameters [e.g., minimal micro-void formation energy (E h ), glass’s fragility index (m), micro-void volume (V h ), etc] and the covalent character of the glassy system. Additionally, various physical parameters, including density, molar volume, and compactness, have also been determined. The results emphasize that the different thermo-mechanical parameters investigated in this study achieve their most extreme values at the highest concentration of Zn. However, the energy of micro-void formation within the glassy network of quaternary glasses remains relatively unchanged after the introduction of Zn into the parent STS alloy;

Short review and prospective: chalcogenide glass mid-infrared fibre lasers

Rare-earth ion doped, silica glass, optical fibre amplifiers have transformed the world by enabling high speed communications and the Internet. Fibre lasers, based on rare-earth ion doped silica glass optical fibres, achieve high optical powers and are exploited in machining, sensing and medical surgery. However, the chemical structure of silica glass fibres limits the wavelength of laser operation to < 2.5 µm, which excludes the mid-infrared longer wavelength range of 3–50 µm. Rare-earth ion doping of fluoride glasses enables manufacture of fibre lasers up to a limiting 3.92 µm wavelength, but the fluoride glass chemical structure again prevents operation at longer wavelengths. Optical fibre lasers that are constructed from different rare-earth ion doped chalcogenide glass fibres will potentially operate across the 4–10 µm wavelength range, where suitable high-power lasers currently do not exist. We present a short review here of our recent work in achieving first time, continuous wave, mid-infrared fibre lasing beyond 5 μm wavelength in Ce3+-doped selenide chalcogenide fibre. We place this disruptive breakthrough into the wider fibre laser context, and also present the unprecedented advances in new cross-sector applications that will be enabled by mid-infrared fibre lasers in the 4–10 µm wavelength range. To surpass the few mW power output of the Ce3+-doped chalcogenide glass fibre lasing achieved to date, the glass quality of the doped chalcogenide fibres must now be improved, similar to the challenges originally facing the first glass fibre lasers based on silica.

Structural and vibrational characteristics of Ge-S-Br glass system: ab initio calculation and Raman study

To improve the understanding of the structure network of chalcogenide glass, we report an investigation of the structure and vibrational property of the Ge-S-Br system chalcogenide glass. The structural origin was interpreted by the result of ab initio calculation performed on the basic units such as ethane-like(ETH) structure(Ge2S6 and Ge2Br6),edge-sharing(ES) structure Ge2S2SnBr4-n (n=0,1,2,3,4) and isolated GeSnBr4-n tetrahedron (n=0,1,2,3,4), which represent the local structure of Ge-S-Br glassy system. In addition, We have compared the experimental spectra of GeS2, GeS3Br, GeSBr2 glasses and liquid GeBr4 to the calculated main vibrational modes of basic units by ab initio calculation. The calculated vibrational modes of the GeSnBr4-n cluster are assigned by group theory. Moreover, the symmetrical stretching modes related to the Ge-S and Ge-Br bond are in accordance with the vibrational coupling theory. The variation of calculated main vibrational modes of GeSmBrn clusters reveals the structure formations of Ge-S-Br glassy system with different S/Br ratios, which can be in agreement with vibrational spectra of Ge-S-Br glass.

Glass Stability and Glass Forming Ability of Ge25−xSe75Sbx (x = 12, 15, and 18) Chalcogenide Glasses Using Thermal Parameters

AbstractIn the present communication glass stability (GS) and glass forming ability (GFA) of Ge25−xSe75Sbx (x = 12, 15, and 18) chalcogenide glasses have been calculated in terms of certain thermal parameters, i.e., reduced glass transition temperature (Trg), Hruby number (H), S‐parameter (S), and ΔT. The glassy samples have been prepared by quenching of melt technique. For structure characterization, XRD technique has been used. For thermal analysis Differential Scanning Calorimetery (DSC) has been used. DSC scans have been recorded at different heating rates, i.e., 5, 10, 15, and 20 K min−1. Stability of glassy samples has also been confirmed in terms of activation energy of glass transition calculated by Kissinger relation. All these parameters indicate that GS and GFA both decrease with increase of Sb content in Ge25−xSe75Sbx (x = 12, 15, and 18) glassy series.

Structural relaxation of Sb2Se98 chalcogenide glass and its effect on following crystallization

This work focuses on a comprehensive study of the structural relaxation of chalcogenide glass and the possible influence of relaxation on subsequent crystallization. Chalcogenide glass of composition Sb2Se98 was studied using differential scanning calorimetry. Non-isothermal cyclic experiments were performed, as well as isothermal annealing at temperatures in the range of 25–35 °C. The Tool-Narayanaswamy-Moynihan model was used to describe the relaxation data, and all methods of estimating some of its parameters were applied. Finally, the parameters were refined by numerical fitting and their values for individual types of experiments are discussed. The reproducibility of individual relaxation datasets is also described in detail. Attention is also paid to subsequent crystallization after the relaxation experiments.

Efficient Parametric Frequency Conversions in Chalcogenide‐Loaded Etchless Thin‐Film Lithium Niobate Waveguides

AbstractParametric frequency conversion based on second‐order nonlinearity (χ(2)) is critical in many applications. The implementation of second‐order nonlinearity on integrated photonic platforms, in particular on the lithium niobate‐on‐insulator platform, has attracted considerable interest due to its low power consumption and small footprint. However, high‐efficiency on‐chip parametric frequency conversion remains challenging due to fabrication complexity. Here, efficient parametric frequency conversions via modal phase matching (MPM) in etchless thin‐film lithium niobate (TFLN)‐chalcogenide glass (ChG) hybrid waveguides fabricated by a simplified process free from domain engineering and etching of TFLN are proposed and demonstrated. An overall conversion efficiency of 25.55% W−1 for second‐harmonic generation is experimentally achieved in a 1‐cm‐long waveguide, significantly over the reach of the etchless counterparts and in the same order of magnitude as those of the etched cases based on MPM. Broadband frequency conversion with a 3‐dB bandwidth of 57 nm is achieved based on cascaded second‐harmonic generation and difference‐frequency generation via MPM in a nanophotonic waveguide using a continuous‐wave pump. This device shows great promise for efficient on‐chip parametric frequency conversion, enabling a wide range of photonic applications, and paving the way for further integration with various advanced ChG photonic devices toward on‐chip multifunctional microsystems.

Modified Chalcogenide Glass Equations for the Activation Energy of Crystallization

For over six decades, chalcogenide glasses (ChGs) have played a pivotal role in the optical community, fostering innovations and new applications in photonics, electronics, and electro-optics. In the last decade, the exploration of novel applications, such as Gradient Index (GRIN) ChGs, has underscored the need for a nuanced comprehension and precise control of nucleation and crystallization kinetics in emerging infrared glass compositions. This article explores the activation energy of crystallization in amorphous materials, particularly focusing on ChGs. It identifies long-standing challenges associated with existing models used for crystal growth in nucleated glasses. Employing carefully outlined mathematical logic, our study critiques conventional models and introduces innovative equations centering around the need for balanced units and proper physical trends. These new models overcome some shortcomings of the established framework and provide a more accurate depiction of crystallization kinetics. To validate the efficacy of our proposed models, we conducted a comparative analysis using differential scanning calorimetry data from a recently published Sb-Te-Se chalcogenide glass composition. The numerical and graphical results clearly illustrate the improvements inherent in our models and their practical utility. Beyond ChGs, our models and equations have broader applications. They may extend to oxide, halide, oxy-halide, and fluoride glass compositions, as well as polymers, contributing new tools to the understanding of crystallization kinetics across diverse materials.

Investigation on gallium doping Ge-As-S chalcogenide glass and glass ceramics

In this work, bulk chalcogenide glasses (Ge35As10S55)100-xGax (x = 0,1,3,5,7,9) were prepared using the traditional melt quenching method, and glass ceramics were prepared to improve the mechanical properties through heat treatment. Optical, thermal and mechanical properties of the glass and glass ceramic samples were measured by FTIR, DSC and Vickers hardness analysis. Results indicate that glass samples exhibited about 70% IR-transmission around 3–12 µm. The hardness of these pure glasses increased from 231 to 282 kgf/mm2 through gallium doping and improvement of melt-quenching conditions. The type of nanocrystals precipitated in the glass ceramics were characterized by XRD. Existence of a γ-Ga2S3 crystal phase enhanced the hardness of the glass. Also, the size and distribution of nanocrystals in the microstructure of the glass ceramics were investigated by SEM. The hardness of (Ge35As10S55)93Ga7 glass reached to 302.6 kgf/mm2 by precipitation of nanocrystals with diameter smaller than 500 nm.

Femtosecond laser induced damage threshold incubation and oxidation in AS2S3 and AS2Se3 thin films

Laser surface structuring has emerged as a versatile technology for precise and localized material processing. When dealing with femtosecond lasers, thermal effects and collateral damage are reduced due to nonlinear light-matter interaction, improving the processing. This study explores the fabrication of microstructures using femtosecond pulses on thin films of chalcogenide glasses, which can be used for photonics applications, such as waveguides, fiber lasers, and photonic crystals. Moreover, the photoinduced changes in chalcogenide glasses have opened up new possibilities in optoelectronics, data storage, and other applications. Femtosecond laser machining of amorphous thin films of As2S3 and As2Se3 using femtosecond laser pulses is investigated through various microscopy techniques and spectroscopy tools, focusing on the impact of incubation effects and controlled photo-oxidation. This research contributes to a deeper understanding of the interaction of ultrafast pulses with chalcogenide glasses, promoting further advancements in photonics and optoelectronic applications.

Direct femtosecond laser writing fiber Bragg gratings in double-D cladding chalcogenide glass infrared fibers

Chalcogenide glass (ChG) fiber Bragg grating (FBG) is one of the key components in monolithic infrared fiber lasers and sensors. However, its effective fabrication using direct femtosecond laser writing is still seldom reported, owing to complications attributable to ChG. In this study, a double-D shaped ChG fiber was used to fabricate FBGs with high reflectivity (a 20.5 dB dip in the transmittance) and narrow 3-dB bandwidth (164 pm) using direct femtosecond laser writing. The high sensitivity to laser powers of the direct writing of the ChG FBG was revealed and understood from the perspective of the low laser-induced damage threshold of ChGs. Lower-order reflectance of the directly written FBGs at the mid-infrared wavelength region were quantitively predicted to have higher reflectivity. These results provide a robust method of writing FBGs with arbitrary periods in ChG fibers, establishing a solid foundation for the development of infrared fiber lasers and fiber sensors.

Investigation of Indium doped Se-Te bulk chalcogenide glasses for electrical switching and phase changing applications

Recently, Metal-doped Se-Te chalcogenides have gained a lot of interest due to their unique capacity for electrical switching, which makes them desirable for electronic applications. This study examines the electrical switching characteristics of bulk Se86−xTe14Inx (0 ≤ x ≤ 6) amorphous alloys produced by the conventional melt-mix-quench process. The samples with an Indium atomic percentage between 2 to 6 exhibited a remarkable transition from a highly resistive to a low resistive state when subjected to an electric field with a current of 1 mA, displaying quick and reversible switching behaviour. The threshold voltage (Vth) significantly dropped from 410.6 V to 49.2 V with an increase in Indium concentration. Additionally, above the specific current threshold, these bulk glasses demonstrated memory-type switching, demonstrating their potential for data storage applications. To comprehend the trend of glass forming ability, thermal stability range and Hruby’s glass stability parameters, with their compositional dependency, Differential Scanning Calorimetry (DSC) was utilized. The sample Se80Te14In6 emerged to be the fastest phase-changing material, with a memory switching current threshold of Ith = 1.3 mA and a threshold voltage value of 49.2 V. To study the formation of crystallites in Se-Te-In alloy, X-ray diffraction patterns of pristine glass and the annealed sample were examined. Furthermore, temperature-dependent conductivity investigations showed a sharp rise in conductivity once the process crystallization begins (Tx), and also the threshold voltage (Vth) of the samples decreased linearly with rising temperature. Overall, this study provides valuable insights into the electrical switching behaviour and thermal properties of Se-Te-In chalcogenide glasses, enhancing their suitability in electronic devices.

Waveguide‐Based On‐Chip Photothermal Spectroscopy for Gas Sensing

AbstractOn‐chip waveguide spectroscopic sensors have attracted considerable attention due to its potential for large‐scale integration. However, existing waveguide gas sensors based on direct absorption spectroscopy (DAS) suffer from limited sensitivity and measurement range. Here waveguide‐based on‐chip photothermal spectroscopy (PTS) is demonstrated for gas detection with high sensitivity and large dynamic range. On‐chip photothermal field due to non‐radiation relaxation of gas molecules and the resulted photothermal phase modulation are analyzed. By selecting chalcogenide glass (ChG) as the core‐layer material and fabricating thermally‐isolated ChG‐on‐SU8 waveguide for thermal field accumulation, a twofold increase in photothermal phase modulation is achieved as compared to ChG‐on‐SiO2 waveguides. Different from the major concern of multi‐path etalon noise in DAS, piezoelectric transducer noise in the interferometer is identified as the main source in this PTS. For a fair comparison, acetylene (C2H2) detection experiments are conducted using PTS and DAS with a 2 cm‐long ChG‐on‐SU8 waveguide. A remarkable sensitivity of 4 parts‐per‐million (ppm) is achieved, which is 16 times better than that of DAS. The dynamic range extends over five orders of magnitude for PTS, ≈3 orders of magnitude larger than that of DAS. Such high performance opens the possibility of fully‐integrated chip‐level sensors for low‐power, light‐weight applications.

Kinetics of thermally induced processes in Ag doped As40Se30Te30 chalcogenide glass

The processes of glass-transition and crystallization of chalcogenide glass As40Se30Te30 with 5 at.% silver were analyzed using differential scanning calorimetry. The values of glass-transition temperatures and activation energy were determined. Two crystallization processes were also detected and three-dimensional growth. Using non-isoconversional models the activation energies for both processes amounted to 112(2) kJ/mol and 97(2) kJ/mol. Isoconversional models were used to track changes in activation energy. The presence of Te significantly affects the thermal parameters as well as the structure of the glass while the presence of Ag does not significantly change the degree of connectivity of the As40Se30Te30 glass matrix.

Structural evolution of Ge&lt;sub&gt;20&lt;/sub&gt;Se&lt;sub&gt;80–&lt;/sub&gt;&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Te&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; glass networks and assessment of glass properties by theoretical bandgap

Infrared imaging systems are being updated towards greater performance as well as lighter and smaller devices. Developing infrared materials with special properties is a critical for enhancing the performance of optical systems as well as miniaturizing devices. Chalcogenide glass becomes a popular option for advanced IR materials due to its component-property tunability. Se—based glasses such as Ge&lt;sub&gt;33&lt;/sub&gt;As&lt;sub&gt;12&lt;/sub&gt;Se&lt;sub&gt;55&lt;/sub&gt;, Ge&lt;sub&gt;10&lt;/sub&gt;As&lt;sub&gt;40&lt;/sub&gt;Se&lt;sub&gt;50&lt;/sub&gt;, and As&lt;sub&gt;40&lt;/sub&gt;Se&lt;sub&gt;60&lt;/sub&gt;, which completely cover the mid- and long-wave infrared windows, are the most typical materials used in infrared equipment. However, these classical materials can no longer meet the requirements of high-performance imaging systems, and adding more elements such as Te, Ga, Sb, and Ag to enhance the performance is a reliable way to solve this problem. By analysing the structure and properties of the Ge&lt;sub&gt;20&lt;/sub&gt;Se&lt;sub&gt;80–&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Te&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; glass system, the law of its structure and properties evolving with Te content is illustrated. The obtained typical results are shown below. With the increase of Te content, the glass transition temperature (&lt;i&gt;T&lt;/i&gt;&lt;sub&gt;g&lt;/sub&gt;) increases and then decreases, which is caused by the network structure and the average bond energy; the density and refractive index increase in an approximately linear gradient; the Abbe number gradually increases, while the Vickers hardness hardly changes with Te content; the fracture toughness decreases with the Te content increasing. Aiming at the problem that the average coordination number is unable to evaluate the glass systems composed of two or more elements from the same main group, a theoretical bandgap-glass property evaluation system is successfully established. The functional relationships among parameters such as density, refractive index, Abbe number, and fracture toughness, and theoretical band gap are established for Ge&lt;sub&gt;20&lt;/sub&gt;Se&lt;sub&gt;80–&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Te&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; glass system as shown in the summary figure, which can be used to rapidly evaluate the glass components and properties.

Relation between Mean-Field Theory and Atomic Structures in Chalcogenide Glasses

The authors conducted various of X-ray and neutron scattering experiments on typical chalcogenide glasses and clarified the relationship between the atomic structure and simple rigidity percolation theory.

Optical and chemical properties of As–Se and As–S–Se solution processed thin films prepared via As50Se50 source solution modification

This work presents the prospect of As–S–Se and As–Se thin film preparation from a modified solution of As50Se50 chalcogenide glass in ethylenediamine.

Exploring the Potential of Chalcogenide Lens Designs for Cost-effective LWIR Systems

The high cost of optical raw materials in the long wavelength infrared (LWIR) region necessitates the development of cost-effective solutions without compromising resolution. Chalcogenide glasses offer a faster and easier production process compared to growing single crystals of Germanium (Ge). Additionally, they can be molded into complex optical surfaces, reducing processing costs further for serial production. In this study, we explore the potential of chalcogenide lenses. Our comprehensive design study demonstrates that chalcogenide lens designs can achieve comparable or even superior optical performance with reasonable system complexity when compared to a wide-angle benchmark Ge design.