As2S3 Glass Research Articles

Laser Desorption Ionization of As2Ch3 (Ch = S, Se, and Te) Chalcogenides Using Quadrupole Ion Trap Time-of-Flight Mass Spectrometry: A Comparative Study.

Laser desorption ionization using time-of-flight mass spectrometer afforded with quadrupole ion trap was used to study As2Ch3 (Ch = S, Se, and Te) bulk chalcogenide materials. The main goal of the study is the identification of species present in the plasma originating from the interaction of laser pulses with solid state material. The generated clusters in both positive and negative ion mode are identified as 10 unary (S p+/- and As m+/- ) and 34 binary (As m S p+/- ) species for As2S3 glass, 2 unary (Se q+/- ) and 26 binary (As m Se q+/- ) species for As2Se3 glass, 7 unary (Te r+/- ) and 23 binary (As m Te r+/- ) species for As2Te3 material. The fragmentation of chalcogenide materials was diminished using some polymers and in this way 45 new, higher mass clusters have been detected. This novel approach opens a new possibility for laser desorption ionization mass spectrometry analysis of chalcogenides as well as other materials. Graphical abstract ᅟ.

Research on structure and mid-infrared photoluminescence of Ga3 +/Er3 + co-doped As-S glasses

In this study, a series of Ga-As-S glasses tailored by adding Ga as the host for Er3+ ions were prepared and characterized. The effects of the introduction of Ga on the structure change and the Er3+ middle infrared emission intensity have been studied by Raman scattering, X-ray diffraction and fluorescence spectra. The results show the incorporating of Ga into the As2S3 glass induced the dissociation of [AsS3/2] pyramids units in behalf of forming tetrahedral [GaS4/2]. By adjusting the Ga content, this host can be doped up to 2mol% Er3+ without crystallization and concentration quenching effect. Besides, this system has very good thermal stability (ΔT>230°C) and strong broadband mid-infrared emission centered at 4700nm, suggests that this system has the potential to be used as mid-infrared fiber material.

Nanoscale mechanism of rare‐earth doping in Ga‐codoped glassy As‐Sb selenides

AbstractThe method of annihilating positrons in positron annihilation lifetime measuring mode is applied to study mechanism of rare‐earth doping in Ga‐codoped arsenic selenide As2Se3 glass modified with Sb. The atomic‐deficient structure of parent As2Se3 glass is imagined as containing positron‐trapping sites in the form of free‐volume voids within cycle‐type arrangement of corner‐sharing trigonal AsSe3/2 pyramids, composed of atomic‐accessible geometrical holes arrested by surrounding atomic‐inaccessible Se‐based bond‐free solid angles. The Ga codoping in As2Se3 glass causes gradual decrease in trapping rate and fraction of trapped positrons due to agglomeration of free‐volume voids. Partial As‐to‐Sb replacement in Ga‐codoped As‐Se glasses leads to better stability against crystallization processes and possibility to further rare‐earth doping without principal changes in the type of positron‐trapping defects. Effect of 500 wppm of Pr3+ in Ga2(As0.28Sb0.12Se0.60)98 glass is explained in terms of competitive contribution of changed occupancy sites in Ga‐modified glassy network available for rare‐earth ions and annihilating positrons.

Broadband and Wavelength-Dependent Chalcogenide Optical Fiber Couplers

We present optical fiber couplers made of As2Se3 glass. Broadband and wavelength-dependent couplers are fabricated from fibers of engineered core/cladding diameter ratios. Coupling ratios at the through-cross ports ranging from 50%–50% down to 1%–99% are achieved. The transparency of As2Se3 glass over the spectral range of 1.5–12.0 $\mu \text{m}$ makes it a material of prime interest for the fabrication of mid-infrared couplers.

Compositional anomalies in Se-rich As-Se glass-forming system as revealed from positron annihilation lifetime spectroscopy and ab initio cluster modeling

Positron annihilation lifetime spectroscopy in high-measurements statistics supported by ab initio quantum chemical modeling developed within cation-interlinking network cluster approach were used to examine compositional peculiarities of free-volume evolution in Se-rich As-Se glasses. Existence of some anomalies in the studied glasses observed as jump in the defect-related positron lifetime near average coordination Z≈2.33 and strong growing trend approaching Z=2.40 is justified. These features correspond to evolution of glassy network due to free-volume elements based on solid angle free of bond charge associated with Se atoms in a vicinity of heteropolar chemical bonds. The results are explained within structural models of optimized network of As-Se glasses composed of AsSe3/2 pyramids interlinked by variable-length Se-chains.

Raman gain and femtosecond laser induced damage of Ge-As-S chalcogenide glasses.

Chemical stoichiometric Ge-As-S glasses were prepared, and their thermal properties, refractive index (n), optical bandgap, Raman gain, and femtosecond laser damage were examined. Results revealed that the n and density (ρ) of the glasses decreased as Ge concentration increased, whereas the bandgap and glass transition temperature (Tg) increased. The Raman gain coefficients (gR) of the samples were calculated on the basis of spontaneous Raman scattering spectra. gR decreased from 2.79 × 10-11 m/W for As2S3 to 1.06 × 10-11 m/W for GeS2 as Ge concentration increased. However, the smallest gR was 100 times higher than that of fused silica (0.89 × 10-13 m/W). When these glasses were irradiated by a laser with a pulse width of 150 fs and a power of 33 mW at 3 μm, the damaged area and depth decreased and the damage threshold increased gradually as Ge concentration increased. Raman spectra and composition analysis indicated that surface oxidation probably occurred and sulfur gasified at a high laser power. Although the gR decreased as Ge was added, the laser damage threshold of Ge-As-S glasses was higher than that of the As2S3 glass. Thus, these glasses are potential materials for Raman gain media.

Supercontinuum generation in the normal dispersion regime using chalcogenide double-clad fiber

We experimentally demonstrate mid-infrared (MIR) supercontinuum (SC) generation in a 2.8-cm-long chalcogenide double-clad fiber (Ch-DCF). The Ch-DCF made of As2Se3, AsSe2, and As2S5 glasses has near-zero chromatic dispersion in the normal dispersion regime. We pump the Ch-DCF using a 200 fs pulse laser at 10 µm, and obtain MIR SC extending from 2 to 14 µm. Numerical results show that the Ch-DCF has the potential of generating a highly coherent MIR SC light source.

The influence of Sb on glass-forming ability of Ga-containing As2 Se3 glasses

Effect of As to Sb substitution on glass-forming ability of As2Se3 glass under Ga additions was comprehensively studied using optical spectroscopy in visible and IR regions, differential scanning calorimetry, X-ray diffraction as well as Raman scattering techniques. The crystallization processes enhanced by Ga additions to As2Se3 glass were significantly suppressed under such As to Sb substitution. Following conventional synthesis, it was possible to substitute up to 50% of As by Sb within Gay(As0.40−xSbxSe0.60)100−y cut-section without essential impact on glassy state, thus improving optical properties in the IR region by lowering the phonon energy. In the case of Gay(As0.28Sb0.12Se0.60)100−y cut-section, up to 8 at.% of Ga can be introduced without crystallization, whereas in case of Gay(As0.40Se0.60)100−y system, glass-forming ability is limited just up to 3 at.% of Ga. The prepared Ga5(As0.28Sb0.12Se0.60)95 glass composition was shown to be the richest in Ga keeping its vitreous state, good optical and thermodynamic properties allowing further rare-earth doping and fiber drawing.

Effect of aluminum and tellurium tetrachloride addition on the loss of arsenic selenide optical fiber

Arsenic selenide glass optical fibers typically possess extrinsic absorption bands in the infrared wavelength regions associated with residual hydrogen and oxygen related impurities, despite using 6N purified elemental precursors. Consequently, special additives and refined processing steps are utilized in an attempt to reduce these and other impurities. We investigate the formation of particulate impurities during a purification process based on the addition of 0.1 wt% elemental aluminum (Al) and 0.2 wt% tellurium tetrachloride (TeCl4) during glass synthesis. It was found that during purification and melting steps, Al reacts with TeCl4 to form AlCl3, which in turn reacts with oxygen and hydrogen impurities and the fused quartz (SiO2) ampoule to produce HCl and stable submicron Al2SiO5 compounds in the As-Se glass and fibers. The intensity of the H-Se absorption band centered at 4.57 μm has been significantly reduced from 18 dB/m to 0.8 dB/m. Using thermodynamic data, we have identified stable Al2SiO5 submicron inclusions in the glass and fibers. A two-step gettering process is proposed as a solution to eliminating these inclusions.

Wetting, surface tension, and work of adhesion of As2S3 and As2Se3 glass melts to quartz glass

The contact angles of the quartz glass surface by the As2S3 and As2Se3 glass melts and surface tension of these glass melts in the temperature range of 325–370°С have been experimentally measured. The polytherms are linear and possess negative slope in the mentioned temperature range. The work of the adhesion of As2S3 and As2Se3 glass melts to the quartz glass surface has been calculated and compared to the data on the adhesion strength of the As2S3–SiO2 and As2Se3–SiO2 boundaries of the solid phases.

Stress Relaxation and Refractive Index Change of As2S3 in Compression Molding

As2S3 is one of the chalcogenide glasses that have attracted increasing interests for compression molding applications. This article aimed to evaluate the stress relaxation behavior of As2S3 above its glass transition temperature and calculate its refractive index change during cooling. First, creep tests were conducted with cylinder glass specimens at three different temperatures, in order to deduce the shear stress relaxation function by using the relationship with creep compliance function. In addition, the shift factor for thermo‐rheological simplicity using Williams–Landel–Ferry equation was obtained. Then, finite element simulation was implemented to verify the calculated shear stress relaxation function. The acquired shear stress relaxation function needs to be modified to compensate the influence of friction on the thickness change in the experiments, so that the simulation results using the modified shear stress relaxation would match the experiments better. Finally, the refractive index changes of As2S3 at different cooling rates were modeled by using the Tool–Narayanaswamy–Moynihan (TNM) model for structural relaxation behavior. It is confirmed that the slower the cooling rate is, the less the refractive index drop will be. It was also demonstrated that the refractive index drop is strictly dependent on the cooling rate logarithmically by using TNM model. In summary, the results presented in this article can provide reliable references for viscoelastic characterization of As2S3 glass, crucial for compression molding or similar applications.

Thermo-tunable hybrid photonic crystal fiber based on solution-processed chalcogenide glass nanolayers.

The possibility to combine silica photonic crystal fiber (PCF) as low-loss platform with advanced functional materials, offers an enormous range of choices for the development of fiber-based tunable devices. Here, we report a tunable hybrid silica PCF with integrated As2S3 glass nanolayers inside the air-capillaries of the fiber based on a solution-processed glass approach. The deposited high-index layers revealed antiresonant transmission windows from ~500 nm up to ~1300 nm. We experimentally demonstrate for the first time the possibility to thermally-tune the revealed antiresonances by taking advantage the high thermo-optic coefficient of the solution-processed nanolayers. Two different hybrid fiber structures, with core diameter 10 and 5 μm, were developed and characterized using a supercontinuum source. The maximum sensitivity was measured to be as high as 3.6 nm/°C at 1300 nm. The proposed fiber device could potentially constitute an efficient route towards realization of monolithic tunable fiber filters or sensing elements.

Enhanced surface patterning of chalcogenide glass via imprinting process using a buffer layer

In an effort to enhance transcriptability of quasi-three-dimensional patterns present in silicon stamp onto the surface of ‘bulk’ chalcogenide glass, a buffer layer was introduced during the replication process via imprinting. Dissimilar patterns with diverse depths along the surface normal direction were imprinted with or without the buffer layer, and the resulting patterns on the glass surface were compared with regard to the transcription quality in both the lateral and vertical directions. After assessing the processing conditions appropriate for imprinting bulk As2S3 glass especially in terms of temperature and duration, candidate materials suitable for the buffer layer were screened: Commercially available polydimethylsiloxane was then chosen, and impact of this buffer layer was elucidated. The imprinted patterns turned out to become more uniform over large surface areas when the buffer layer was inserted. This finding confirmed that the use of buffer layer conspicuously enhanced the transcriptability of imprinting process for bulk chalcogenide glass.

Preparation of core-clad arsenic rich As[sbnd]Se glass fiber

Samples of arsenic-rich AsSe glasses with the low content of limiting impurities are prepared; their transmission, Raman spectra and thermal properties are investigated. It is found that the As46Se54÷As50Se50 glasses do not crystallize during annealing and DSC analysis at a heating rate of 2.5÷10K/min, as opposite of the As40Se60 composition. For the first time, using a double crucible technique, the rods of high pure As48Se52 and As46Se54 glasses are drawn into a core-clad optical fiber. Over 100m of this fiber with core diameter of 550μm, cladding diameter of 600μm and protective F-42 fluoroplastic coating are produced. The prepared arsenic-rich As48Se52/As46Se54 glass fiber has a good mechanical strength, invariable optical transmittance along the fiber length and the minimum optical losses of 260dB/km at a wavelength of 3.1μm.

Simulation and fabrication of micro-structured optical fibers with extruded tubes

Chalcogenide glass is fragile and devitrifiable to be fabricated into micro-structured optical fibers (MOFs). In this article, MOFs which have jacket tubes with inner hexagon are designed and fabricated. The optical properties, such as effective refractive index, electric field intensity, effective mode area, nonlinear coefficient and chromatic dispersion of the fundamental mode are simulated by using full-vectorial finite element method (FVFEM). The effects of structural parameters variation on these optical characteristics of the proposed MOFs are investigated. Furthermore, the As2S3 glass capillaries and jacket tubes are made by extrusion. The MOF with three layers of capillaries is fabricated by the “Stack & Draw” technique. The lowest attenuation of 6.34dB/m of the MOF is measured at the wavelength of 4.61μm using the cut-back method.

Mid-infrared supercontinuum generation in tapered As2S3 chalcogenide planar waveguide

We numerically demonstrate mid-infrared supercontinuum generation in a non-uniformly tapered chalcogenide planar waveguide. This planar rib waveguide of As2S3 glass on MgF2 is 2 cm long with increasing etch depth longitudinally to manage the total dispersion. This waveguide has zero dispersion at two wavelengths. The dispersion profile varies along the propagation distance, leading to continuous modification of the phase-matching condition for dispersive wave emission and enhancement of energy transfer efficiency between solitons and dispersive waves. Numerical simulations are conducted for secant input pulses at a wavelength of 1.55 μm with a width of 50 fs and peak power of 2 kW. Results show this proposed scheme significantly broadens the generated continuum, extending from ~1 to ~7 μm.

Free-Volume Nanostructurization in Ga-Modified As2Se3 Glass.

Different stages of intrinsic nanostructurization related to evolution of free-volume voids, including phase separation, crystalline nuclei precipitation, and growth, were studied in glassy As2Se3 doped with Ga up to 5 at. %, using complementary techniques of positron annihilation lifetime spectroscopy, X-ray powder diffraction, and scanning electron microscopy with energy-dispersive X-ray analysis. Positron lifetime spectra reconstructed in terms of a two-state trapping model testified in favor of a native void structure of g-As2Se3 modified by Ga additions. Under small Ga content (below 3 at. %), the positron trapping in glassy alloys was dominated by voids associated with bond-free solid angles of bridging As2Se4/2 units. This void agglomeration trend was changed on fragmentation with further Ga doping due to crystalline Ga2Se3 nuclei precipitation and growth, these changes being activated by employing free volume from just attached As-rich glassy matrix with higher content of As2Se4/2 clusters. Respectively, the positron trapping on free-volume voids related to pyramidal AsSe3/2 units (like in parent As2Se3 glass) was in obvious preference in such glassy crystalline alloys.

Fabrication of ultrafast laser written low-loss waveguides in flexible As₂S₃ chalcogenide glass tape.

As2S3 glass has a unique combination of optical properties, such as wide transparency in the infrared region and a high nonlinear coefficient. Recently, intense research has been conducted to improve photonic devices using thin materials. In this Letter, highly uniform rectangular single-index and 2 dB/m loss step-index optical tapes have been drawn by the crucible technique. Low-loss (<0.15 dB/cm) single-mode waveguides in chalcogenide glass tapes have been fabricated using femtosecond laser writing. Optical backscatter reflectometry has been used to study the origin of the optical losses. A detailed study of the laser writing process in thin glass is also presented to facilitate a repeatable waveguide inscription recipe.

Raman gain of Ge-Sb-Se chalcogenide glass

Previously reported chalcogenide glass Raman fiber lasers are made of glass compositions such as As2S3 or As2Se3. However, due to the high toxicity of the element arsenic, there is a potential risk in the glass preparation, fiber drawing, and testing processes. Therefore, we need to explore new environmentally friendly chalcogenide glasses that do not contain As for Raman fiber lasers. Studies have shown that the chalcogenide glasses of Ge-Sb-Se system have excellent infrared transmissions and good environmental friendliness, and thus they are excellent candidates for chalcogenide glass Raman fiber lasers. However, their Raman gains have not been reported. Then Raman gain coefficients can be obtained by experimental measurements and theoretical analyses. The experimental method requires expensive laboratory equipments, a complex optical path, and precision adjustments. Therefore, the design and preparation of new chalcogenide glass fiber with high Raman gain require the theoretical analysis of the Raman gain characteristics in a particular glass component glass. In this work, four chalcogenide glasses, respectively, with compositions of As2S3, As2Se3, Ge20Sb15Se65 and Ge28Sb12Se60 (mol%) are prepared. Refractive indices, infrared transmission and Raman spectra of these glass samples are measured. By using spontaneous Raman scattering theory combined with the measured Raman spectral data, the values of Raman gain coefficient gR of the chalcogenide glasses are calculated and calibrated by a quartz glass sample. Results show that the gR of As2S3 glass is 6010-13 m/W at 230 cm-1 Raman shift and the gR of As2Se3 glass is 22310-13 m/W at 340 cm-1 Raman shift, which are consistent with the experimental results reported in the literature. Compared with the traditional method, the present method used for calculating the fiber Raman gain coefficient provides great convenience for exploring new chalcogenide glasses with high Raman gain. By using this method, we obtain the gR values of Ge20Sb15Se65 and Ge28Sb12Se60glasses at 200 cm-1 Raman shift, which are 21510-13 m/W and 11110-13 m/W respectively. Meanwhile, we analyze the effects of composition and network structure of chalcogenide glass samples on the Raman gain coefficient and gain spectrum. There are two Raman peaks at 165 cm-1 and 200 cm-1 Raman shift, which are attributed to Ge-Ge bond vibration and Ge-Se bond vibration of common apex GeSe4/2 tetrahedral structure respectively. It could be found that the Raman gain coefficient of Ge20Sb15Se65 glass is bigger than that of Ge28Sb12Se60glass at 200 cm-1 Raman shift because of more Ge-Se bonds. By further optimizing the ratio of components of Ge-Sb-Se chalcogenide glass, we could obtain higher Raman gain coefficient at a particular frequency shift. These results show that the Raman gain coefficient of Ge-Sb-Se chalcogenide glass without poisonous element is up to over 200 times that of the ordinary quartz glass, which provides a new possibility for environment-friendly Raman fiber laser material.

Structural analysis of Tm3 + doped As–S–Ga glasses by Raman and EXAFS spectroscopy

Structural properties of Tm3+ doped As–S–Ga glasses were investigated using Raman spectroscopy and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy at As K-edge, Ga K-edge and Tm L3-edge. The Raman spectra are interpreted on the basis of comparison with the well-known Raman spectra of As2S3 glasses the structure of which mainly consists of pyramidal [AsS3/2] units interconnected by S–S chains. Incorporation of Ga2S3 in As2S3 glass matrix induced the dissociation of S–S chains in behalf of the formation of tetrahedra [GaS4]. Moreover, introduction of Tm into As–S–Ga glasses forms Tm–S bonds through the further dissociation of [AsS3/2] pyramidal units. The deficiency of S in the glasses is compensated with the formation of As4S4 structural units. The EXAFS results indicate that Ga–S bond distance in the tetrahedra [GaS4] decreases from 2.29Å to 2.26Å with the increase of Tm concentration in the glass. Meanwhile, Tm–S bond distance increases from 2.66Å to 2.71Å approaching to that of crystalline Tm2S3 and simultaneously, the coordination number of Tm gradually decreases from 7 to 4.