Search

Properties of the glasses are experimentally investigated when Ga is gradually substituted by Ge in Ga 8 Sb 32 S 60 chalcogenide glass. The glass structure is also studied to elucidate the variations of the properties. While the substitution of Ga by Ge does not remarkably change the glass transition temperature T g , the thermal stability against crystallization becomes optimum when half of the Ga atoms are replaced by Ge atoms. The short-wavelength absorption edge λ S (or optical bandgap E g ) exhibits a remarkable decrease when a small amount of Ge is added, however, its value does not change significantly with further Ga substitution. As Ga is gradually replaced by Ge, the long-wavelength cut-off edge λ L , the density ρ , the linear refractive index n , and the third-order nonlinear refractive index n 2 decrease. It is shown that the property variations of the glasses could be explained by the evolution of the glass structure. [ABSTRACT FROM AUTHOR]

Fiber combiner is an effective device to enhance the power level or broaden the spectral wavelengths through a single monolithic output aperture, by fusing multiple fibers together. This is particularly important in mid‐infrared (MIR) 2–5 µm range, in which the output power of a single laser is limited. Due to the high MIR transmission, chalcogenide glass is an ideal host for constructing MIR fiber combiner. In this study, we report the design, fabrication, and characterization of a homemade 3 × 1 chalcogenide glass fiber combiner. The fiber combiner includes a 3 × 1 As–S input fiber bundle and an output fiber. The input fiber bundle was made by tapering three As–S multimode fibers with a core diameter of 200 µm and a cladding diameter of 250 µm. The taper reduction ratio R was 2, and the length of the taper transition region was ∼2 cm. The output fiber with core diameter of 360 µm and cladding diameter of 570 µm was then spliced with the tapered end of the fiber bundle. The total length of the combiner was ∼53 cm. The measurement of power combination at 4.56 µm indicated that the transmission efficiency of three ports reached 80%, whereas the power combining efficiency of the combiner was measured to be ∼48%. In addition, efficient wavelength combining over one octave has been demonstrated, by launching three different lasers at 2.1, 3.39, and 4.56 µm through the 3 × 1 combiner. It proves that chalcogenide fiber combiner is promising for the applications of high‐level power combination and broadband wavelength combining in MIR 2–5 µm range. [ABSTRACT FROM AUTHOR]

Infrared graded‐index (GRIN) lenses are desirable for realizing miniaturization and lightweight of infrared imaging systems. Chalcogenide glasses have excellent infrared transparency, good rheological property, and large refractive index range, making them preferred materials for infrared GRIN lenses. In this work, aiming to find thermally matched chalcogenide compositions with high refractive index contrast for preparing GRIN glasses by the stacking diffusion approach, we investigated characteristic temperature, thermal expansion coefficient and refractive index of Ge‐As‐Se and Ge‐As‐Se‐Te glasses, optimized the glass compositions, and evaluated the feasibility of preparing GRIN glass using the optimized chalcogenide glass powders. It is found that Ge20As20Se20Te40 and Ge12As22Se66 glasses have similar softening temperature (247°C vs. 249°C), reasonably difference of thermal expansion coefficient (3.8 ppm/K), and large refractive index contrast (∼.48). The glass powders with composition xGe20As20Se20Te40‐(1‐x) Ge12As22Se66 can be hot‐pressed into glass disks with good transmittance at the same temperature and pressure. Graded refractive index profile is formed near the interface between the layers after the co‐pressed glass is thermally treated. These results demonstrate the prospect of the compositions for preparing infrared GRIN glasses. [ABSTRACT FROM AUTHOR]

Chalcogenide and chalcohalide glasses have been considered promising host materials for thermal imaging lenses and mid-infrared (MIR) optical fibers. In this paper, a novel Ga 2 S 3 -SnS 2 -CsI chalcohalide glass system, with environment-friendly constituent elements, was proposed. The glass forming region was explored, and the physical properties were investigated. The glasses show high transmittance (>60%) over the 1–12 μm spectral range and exhibit relatively high microhardness, making them competitive candidates for manufacturing thermal imaging lenses. Furthermore, the MIR emission property of Dy3+-doped Ga 2 S 3 -SnS 2 -CsI glass was also studied. With strong emissions and high quantum efficiencies at 3.00 μm and 4.38 μm wavelengths, the glass can be potentially used as gain media for MIR lasers. [ABSTRACT FROM AUTHOR]

The choice of gain media significantly affects the efficiency of mid-infrared (MIR) lasers and amplifiers. Transition metal ion-doped glass-ceramics (GCs) are attractive laser gain materials as they have the advantages of both laser crystals and glasses. Transparent GC fibers with efficient MIR emission are currently scarce. The emission properties of Ni2+ ion in GCs are generally studied in an octahedral ligand field, where it emits near-infrared light. The emission properties of tetra-coordinated Ni2+ ions are yet to be explored. Herein, we found a chalcogenide glass host characterized by high crystallinity and prepared transparent Ni2+-doped chalcogenide GC containing ZnS nanocrystals by in-situ crystallization. Moreover, for the first time, we reported the broadband MIR 3–4 μm emission at room temperature from tetra-coordinated Ni2+ in chalcogenide GC fiber embedded with ZnS nanocrystal. The fiber losses were measured to be 18.6 ± 1.1, 9.8 ± 0.6 and 11.4 ± 0.8 dB/m at 2.10, 3.39 and 3.80 μm, respectively. The results indicate that the active chalcogenide GC fiber reported herein can be potentially used to develop MIR-tunable fiber lasers and amplifiers. [ABSTRACT FROM AUTHOR]

The low mechanical properties limit the application of chalcogenide glasses in the infrared lens. This paper proposes a general method for enhancing the mechanical strength of chalcogenide glasses. A series of GaAs crystal-doped Ge 10 As 20 Se 17 Te 53 and ZnS crystal-doped As 2 S 5 glass-ceramics were prepared by spark plasma sintering (SPS). The effects of crystal doping on the optical and mechanical properties of glass-ceramics were studied utilizing FTIR, XRD, SEM, ultramicroscopy, and Vickers hardness. The results show that adding GaAs crystal and ZnS crystal significantly improves the hardness and fracture toughness of the chalcogenide glasses. The infrared transmittance and mechanical properties can be further improved by reducing the crystal size. [ABSTRACT FROM AUTHOR]

Germanium selenide (GeSe) thin films were fabricated by employing femtosecond pulsed-laser deposition (fs-PLD) on silicon (100) substrates at various substrate temperatures, ranging from 25 °C to 600 °C. The thin films' surface morphology qualities and optical properties were studied by utilising transmission electron microscopy (TEM) and X-ray diffraction (XRD). The X-ray diffraction result signifies that the thin films deposited on the silicon at a substrate temperature below 400 °C were amorphous Ge-Se. In contrast, those grown at 400 °C and above exhibited crystallised peaks of Ge-Se orthorhombic and tetragonal structures. The deposition growth rate of the thin films was also found to decrease substantially with increasing substrate temperature. These results show that the fs-PLD process has great potential for fabricating good quality Ge-Se thin film. This technique could enable the manufacture of modern optoelectronic devices for applications in optical communication, sensing, and ovonic threshold switching for the high-density crossbar memory array. [ABSTRACT FROM AUTHOR]

A Co2+:ZnS-doped chalcogenide glass with broadband mid-infrared emission was prepared by using a hot uniaxial pressing process. The refractive index difference (Δn) between matrix glass (As 2 S 5) and crystal (Co2+:ZnS) was controlled to be 0.0042 in the emission spectral range of Co2+ to minimize the scattering effect. An ultrabroadband mid-infrared emission of 2–4 μm was observed at room temperature in the samples after excitation by using a commercially available laser diode of 1550 nm. The significant changes in the lifetime and fluorescence intensity of Co2+:ZnS-doped chalcogenide glass were measured in the temperature range of 90–290 K. A resolution of approximately 0.18 K was observed when used as a temperature detector. Furthermore, a gas-sensing device was built by using the strong and broad emissions of the sample, and the detection sensitivity of butane reached 56 ppm. These results show that this glass-ceramics can be used as optical sensing of gas and temperature. [ABSTRACT FROM AUTHOR]

The development of mid‐infrared (MIR) broadband tunable lasers urgently needs high performance laser gain materials. Transition metal (TM) ions doped glass ceramics are considered to be efficient MIR broadband laser gain media. However, it is difficult to achieve gain because of the large scattering loss and low luminescence efficiency. In this paper, GeS2–Sb2S3–CsI–PbI2 chalcohalide glass ceramics containing CsPbI3 perovskite nanocrystals are fabricated by the melt‐quenching method and subsequent heating treatment. The crystallization behavior of CsPbI3 nanophase and MIR luminescence properties of Ni2+ dopant are systematically investigated. Evidently, spherical CsPbI3 perovskite nanocrystals are precipitated and uniformly distributed in the glassy matrix, which can reduce the light scattering and make the chalcohalide glass ceramics have a high transparency. Moreover, an ultra‐broadband MIR emission in the range of 2.5–5.5 μm is observed for the first time, to our best knowledge, from Ni2+‐doped chalcohalide glass ceramics containing CsPbI3 perovskite nanocrystals. The newly developed Ni2+‐doped chalcohaldie glass ceramics could be promising gain media for MIR broadband tunable lasers. [ABSTRACT FROM AUTHOR]

A step-index chalcogenide fiber with a rectangular core and a circular cladding was fabricated through an approach that combines an extrusion technique and a multiple-stage rod-in-tube method. This fiber has a Ge 12 As 24 Se 64 glass core with a size of ~2.8 μm × 5.9 μm, and a Ge 10 As 24 S 66 glass cladding with a diameter of ~220 μm, and shows a relatively large birefringence. When ~10 cm long fiber was pumped at 4.0 μm with 330 fs pulses, ~2.2–9.5 μm supercontinuum with a flatness of 20 dB and a polarization extinction ratio of ~10 dB was generated. • A chalcogenide glass fiber with a rectangular core is designed. • The fiber is fabricated by an extrusion technique and a rod-in-tube method. • The fiber shows a background loss of about 3.1 dB/m in the mid-infrared. • Polarized ~2.2–9.5 μm supercontinuum is generated in the fiber. [ABSTRACT FROM AUTHOR]

Abstract Mid-infrared (MIR) light sources are indispensable in modern photonic society. In this work, the composites of the As-S-Se chalcogenide glasses containing MIR-emitting ZnSe: Cr2+ submicron-particles are fabricated by two methods, melt-quenching and hot-pressing. The MIR refractive index, transmittance and photoluminescence properties are investigated and compared in the composites prepared by the two methods. Benefiting from the wide glass forming region of the As-S-Se system, it is possible, by tuning the glass composition, to find a glass (e.g., As 40 S 57 Se 3) with the refractive index well matching that of the ZnSe: Cr2+ crystal. The composites prepared by the melt-quenching method have higher MIR transmittance, but the MIR emission can only be observed in the samples prepared by the hot-pressing technique. The corresponding reasons are discussed based on microstructural analyses. The results reported in this article could provide helpful theoretical and experimental information for making novel broadband MIR-emitting sources based on chalcogenide glasses. Highlights • ZnSe: Cr2+ submicron-powders are prepared by the laser ablation method. • As-S-Se glass with matched refractive index with ZnSe: Cr2+ crystal is optimized. • As-S-Se glass containing ZnSe: Cr2+ particles is prepared by two methods. • 1.8–2.7 μm emission is observed in the hot-pressed composites. [ABSTRACT FROM AUTHOR]

Chalcogenide glasses (ChGs) containing II-VI chalcogenide (ChG) nanocrystals such as ZnS/Se have recently been intensively studied as promising mid-infrared nonlinear optics and laser materials, yet preparation of pure-phase II-VI nanocrystals embedded in ChGs via controlled crystallization is still very challenging. In this study, a new system of ChGs and glass ceramics (GCs), viz., (100-x)As2S3- xZnSe (x = 0 ~ 30 mol%), is synthesized, and its physical and optical properties including density, molar volume, microhardness, glass transition temperature, glass network structure, transmission, and refractive index are comprehensively characterized. Significantly, it is initially demonstrated that pure ZnS nanocrystals can be precipitated in GCs simply by a thermal treatment process. The composition and thermal treatment temperature dependencies of crystallization are studied using X-ray diffraction spectroscopy, and the morphology of the nanocrystals by high-resolution transmission electron microscope. The ChG GCs with embedded ZnS nanocrystals retaining good transparency can be a potential host laser material for divalent transition metals (e.g., Cr2+/Fe2+, etc.), and thus used for ultrabroadband tunable continuous or ultra-short-pulsed mid-infrared fiber lasers. [ABSTRACT FROM AUTHOR]

An environment friendly nonlinear chalcogenide glass fiber with a Ge-Sb-Se core and a Ge-Se cladding is fabricated for bright broadband mid-infrared ( MIR) supercontinuum ( SC) generation. The fabricated Ge-Sb-Se/Ge-Se fiber with a core diameter of 6 μm shows zero group velocity dispersion at ~4.2 μm and ~7.3 μm. By pumping the fiber with a length of 11 cm at 4.485 μm with 330 fs pulses, we achieve a SC covering the 2.2-12 μm spectral range and with an output average power of ~17 mW. This bright broadband SC source is promising for high-resolution MIR spectroscopy. [ABSTRACT FROM AUTHOR]

• Fabrication of As 40 Se 60 glass lenses enabled by SPS-SPDT process. • The maximum transmission ratio band from 2 to 18 μm of the spark plasma sintering glass reach to 64% • SPS-SPDT lens has high imaging quality after MTF evaluation. In this paper, we prepare chalcogenide glass (ChG) discs with As 40 Se 60 composition employing spark plasma sintering (SPS) with the advantage of higher raw materials utilization ratio compared with conventional coring and cutting processes. The hardness, composition, structure of the ChG discs are evaluated by HVS, EDS, XRD, Raman characterizations. The Vickers hardness of SPS glass (140.6 HV) is slightly lower than that of base glass. EDS data show that the atomic ratio of SPS glass does not deviate from the base glass. XRD and Raman results confirm that the SPS glass still retains the original amorphous structure. By ultra precision single point diamond turning (SPDT) method, an aspheric lens is fabricated from the SPS glass discs with the lens profile perfectly matched with the design. The modulation transfer function (MTF) of the aspheric lens within the full field of view is above 31%, which is comparable to base glass lenses and indicates lens performance satisfies the requirement of practical imaging devices. [ABSTRACT FROM AUTHOR]

In this study, a novel chalcogenide glass system, Ga-Sb-S, is reported. The glass-forming ability, the physical properties, and the structure are investigated; and the potential applications of the glasses are evaluated. The compositions consisting of ~3%-10% Ga, ~29%-37% Sb, and ~57%-63% S can form glasses. The glasses have a wide transparent window of ~0.8-14 μm, high linear refractive indices of ~2.62-2.70 (@10 μm), high third-order nonlinear refractive indices of ~12.4 × 10−14 cm2/W (@ 1.55 μm), low phonon energy, and large rare earth solubility. These favorable properties make them promising materials for mid-infrared applications such as thermal imaging, nonlinear optics, and lasers. [ABSTRACT FROM AUTHOR]

Novel Ga–Sb–S chalcogenide glasses doped with different amount of Dy 3+ ions were prepared. Their thermal stability, optical properties, and mid-infrared (MIR) emission properties were investigated. The glasses show good thermal stability, excellent infrared transparency, very low phonon energy (∼306 cm −1 ), and intense emissions centered at 2.95, 3.59, 4.17 and 4.40 μm. Three Judd–Ofelt intensity parameters (Ω 2 = 8.51 × 10 −20 cm 2 , Ω 4 = 2.09 × 10 −20 cm 2 , and Ω 6 = 1.60 × 10 −20 cm 2 ) are obtained, and the related radiative transition properties are evaluated. The high quantum efficiencies and large stimulated emission cross sections of the MIR emissions (88.10% and 1.11 × 10 −20 cm 2 for 2.95 μm emission, 75.90% and 0.38 × 10 −20 cm 2 for 4.40 μm emission, respectively) in the Dy 3+ -doped Ga–Sb–S glasses make them promising gain materials for the MIR lasers. [ABSTRACT FROM AUTHOR]

High-purity Ge-As-Se and Ge-As-S chalcogenide glasses were prepared by modified physical and chemical purification techniques. Using the purified glasses, step-index fibers with a small core (~5.5 μm) and large numerical aperture (~1.3) were fabricated. When a 13.5-cm-long fiber was pumped with 320 fs pulses at a repetition rate of 10.5 MHz at 4.1 μm, supercontinuum spanning from ~1.8 to ~9.8 μm with a dynamic range of ±10 dB and an average power of ~3 mW was generated. [ABSTRACT FROM AUTHOR]

Thefragility index (m) of a series of Ge–As–Sglasses covering a wide range of mean coordination (⟨r⟩) and stoichiometry is measured by differentialscanning calorimetry. The evolution of the fragility index appearsto be better predicted by the stoichiometry than the mean coordination,and mshows a well-defined dependence on the departurefrom stoichiometry quantified as the at. % excess or deficiency insulfur. The effect of stoichiometry on the fragility of Ge–As–Sglasses is very similar to that observed in the Ge–As–Sesystem. A systematic Raman spectroscopy investigation also indicatesthe presence of large fractions of molecular species such as S8, As4S4, and As4S3in the structure of some glasses. The presence of molecular speciesis shown to increase the fragility and decrease the glass transitiontemperature (Tg). These results emphasizethat short-range order rather than long-range characteristics suchas structural rigidity appears to control the fragility of chalcogenideglasses. [ABSTRACT FROM AUTHOR]

The production of a broadband supercontinuum spanning from 1.8 μm to >7.5 μm is reported which was created by pumping a chalcogenide glass waveguide with ≈320 fs pulses at 4 μm. The total power was ≈20 mW and the source brightness was [ABSTRACT FROM AUTHOR]

We report a new Dy3+-doped Ga 2 S 3 -Sb 2 S 3 -La 2 S 3 (GSLS) chalcogenide glass for mid-infrared (mid-IR) laser applications. With the addition of La 2 S 3 into the previously studied Ga 2 S 3 -Sb 2 S 3 glass, the thermal stability of the base glass is significantly enhanced. The glass with the composition 20Ga 2 S 3 -75Sb 2 S 3 -5La 2 S 3 (mol.%) shows the best thermal stability for fiber drawing, and the glass can be doped with up to 5 mol.% Dy 2 S 3. The Dy3+-doped GSLS bulk glasses and a multimode fiber exhibit intense emissions at 2.95 μm and 4.40 μm. Spectroscopic analyses show that the mid-IR emissions are with high quantum efficiencies and large stimulated emission cross sections, indicating that Dy3+-doped GSLS glass is a promising candidate for mid-IR fiber laser medium. • A new chalcogenide glass system Ga 2 S 3 -Sb 2 S 3 -La 2 S 3 (GSLS) is developed. • A core/cladding fiber based on Dy3+-doped GSLS glass is fabricated. • The 20Ga 2 S 3 -75Sb 2 S 3 -5La 2 S 3 glass has the best thermal stability. • The Dy3+-doped GSLS glass and fiber show intense mid-infrared emissions. • Fabricated fiber has a background loss of <3 dB/m in the 2–8 μm spectral range. [ABSTRACT FROM AUTHOR]

We have prepared Ge x Se 10 Te 90-x glasses with a composition of x from 17.5 to 26.25 and measured their properties using various diagnosis tools. It was found that, all the glasses have a transmittance more than 40% at a wavelength range from 2 to 15 μm, and linear refractive index n 0 decreases but optical bandgap energy E g increases with decreasing Te contents in the glasses. We also analysed the evolution of n 2 and β as a function of Ge content, both the evolution of n 2 and β are close to the prediction by Sheik-Bahae et al. for optical nonlinearity of semiconductors. In all cases, the nonlinear optical refractive index n 2 measured at 3.0 μm is larger than that at 2.5 μm due to the two-photon resonance effect, and a maximum nonlinear index is 2.46 × 10−13 cm2/W at composition of Ge 17.5 Se 10 Te 72.5. Such larger nonlinearity around 10−13 cm2/W observed in the present paper is one order of the magnitude larger than that in S- and Se-based chalcogenide glasses, demonstrating potentials of Te-based glasses for the applications as mid- and far-infrared nonlinear optical devices. • Glasses show a good transmittance more than 40% from 2 to 15 um. • n 0 decreases but E g increases with increasing Ge (and thus decreasing Te) contents. • A maximum nonlinear index is 2.46 × 10−13 cm2/W at composition of Ge 17.5 Se 10 Te 72.5. [ABSTRACT FROM AUTHOR]