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Gradient refractive index (GRIN) lenses have recently become a hot topic in compact imaging and achromaticity. Current research focuses on exploiting GRIN materials and upgrading the preparation technology. In this study, infrared (IR) GRIN materials were successfully prepared by spark plasma sintering of multilayer chalcogenide glass (ChGs) powders. ChGs powders were derived from the Ge20Se80‐xTex series glasses (x = 0–28 mol%) with a maximum refractive index difference (Δn) of 0.25. The similar glass transition temperatures (ΔTg < 10°C) promote efficient sintering of multilayer powders. Six‐, eight‐, and ten‐layer powders of different compositions were rapidly sintered with a thickness of 600, 300, and 200 µm per layer, respectively. Such tiny layer thickness enables the GRIN materials to exhibit nearly linear refractive index variation. Energy dispersive spectroscopy line scans well characterized the gradient variation of GRIN. The maximum deviation of the refractive index gradient from the fitted target line was only ± 0.016 for the 10‐layer GRIN. The sintered GRIN shows excellent IR transparency, which is of great interest for mid‐wave and long‐wave infrared imaging. [ABSTRACT FROM AUTHOR]

Chalcogenide solid‐state electrolytes (SSEs) have been receiving growing attentions due to their high ionic conductivity and suitable mechanic properties, especially the Li2S–P2S5 systems incorporated with a second glass network formers (Si, Ge, Sn, and so on) besides P. Although the ionic conductivities are generally enhanced with the second glass network formers, the comprehensive effects of different glass formers on other properties, including electrochemical, cycling, and air stability, remain elusive. To acquire deeper understanding, herein, three common but representative glass network formers (SiS2, GeS2, and SnS2) were introduced into Li2S–P2S5, and their individual effects were investigated systematically. The results of multiscale characterizations before and after lithium stripping/plating cycling confirmed that the introduction of metal cations (Ge, Sn) generally leads to worse electrochemical stability and shorter cycle life of these SSEs toward lithium metal compared with SSEs with nonmetal cation (Si) modification. However, the air stability is related to the binding energy of M–S (M = Si, Ge, Sn), which is consistent with the hard base soft acid theory. This work provides valuable understanding for designing pragmatic Li2S–P2S5–MS2‐based SSEs with high electrochemistry, cycling, and air stability. [ABSTRACT FROM AUTHOR]

A series of GeSbSe ( x = 5, 10, 15, 20, 25, and 30 mol%) chalcogenide glasses were prepared by traditional melt-quenching method. The refractive indexes, infrared transmissions, and spontaneous Raman spectra of the glass samples were measured. Based on the spontaneous Raman scattering theory and considering the measured Raman spectral data, we calculated the Raman gain coefficients of the chalcogenide glasses. The effect of Sb on the structures and Raman gain coefficients of the glass samples was then systematically investigated to understand the role of chemical composition in glass structure and Raman gain coefficient. In the GeSbSe glasses, the number of heteropolar Ge-Se, Sb-Se bonds increased, whereas that of homopolar Se-Se bonds decreased at increased Sb concentration. The Raman gain coefficients increased until it reached a maximum value (290 × 10 m/W at GeSbSe) and then decreased when the Sb concentration further increased. These results showed that the Raman gain coefficients of Ge-Sb-Se chalcogenide glasses without poisonous elements were over 300 times of that of commonly fused silica and closely correlated with the structures of the glasses, suggesting that the Raman gain coefficient can be adjusted by modifying the structures of the glasses. This work provides a new possibility for environment-friendly Raman fiber laser and amplifier materials. [ABSTRACT FROM AUTHOR]

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 As 2 S 3 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 6.34 dB/m of the MOF is measured at the wavelength of 4.61 μm using the cut-back method. [ABSTRACT FROM AUTHOR]

Chalcogenide glasses of the GeSbSeI ( x = 0, 5, 10, 15, 20 at.%) system were prepared. This study was performed to examine some Ge-Sb-Se-I glass physical and optical properties, the structural evolution of the glass network, and the optical properties of the infrared glass fibers based on our previous studies. The variation process of the glass physical properties, such as transition temperature, glass density, and refractive index, was investigated from the glass of GeSbSe to the GeSbSeI glass series. The structural evolutions of these glasses were examined by Raman spectroscopy. The GeSbSeI composition was selected for the preparation of the IR fiber. The GeSbSeI glass was purified through distillation, and the intensity of the impurity absorption peaks caused by Ge-O, HO, and Se-H was reduced or eliminated in the purified glasses. Then, GeSbSeI chalcogenide glass fiber for mid-infrared transmission was fabricated using high-purity materials. The transmission loss of the GeSbSeI fiber was greatly reduced compared with that of the GeSbSe glass fiber. The lowest losses obtained were 3.5 dB/m at 3.3 μm for GeSbSeI fiber, which was remarkably improved compared with 48 dB/m of the unpurified GeSbSe fiber. [ABSTRACT FROM AUTHOR]

Chalcogenide glasses are known for their high transparency in the mid-infrared (IR) range, which includes two atmospheric windows that lie from 3 to 5 μm and 8 to 12 μm, respectively. Chalcogenide photonic crystal fibers have numerous potential applications in the field of IR, such as spectroscopy, microscopy, astronomy, biology, and sensing. In this paper, GeSbS chalcogenide glass was fabricated and systematically studied. Chalcogenide glass has high transmission property (>70 %), good thermal stability, and good mechanical stability. The glass transition temperature T is 296 °C, and no exothermic peak was associated with crystallization up to 500 °C, which indicates its suitability for fiber drawing. As a result of its excellent mechanical properties, preforms with a variety of geometrical patterns were fabricated by using mechanical drilling. The near-field intensity distribution image of the drawn fiber shows a strong light propagation confinement. [ABSTRACT FROM AUTHOR]

A series of (1 − x) GeS2.5 - x Sb chalcogenide glasses were prepared using the conventional melt-quenching method. Their microstructure and thermal response were systematically studied. We observe a compositional threshold of x = 0.25 which corresponds to chemical stoichiometric composition in the calorimetric experiments. It is in good accordance with the Raman scattering results and laser-induced phase transformation behavior. They also indicate that phase separation of Sb-rich phase exists in the S-poor samples. Moreover, we got a structural modeling of this phase separation: (1) at x = 0.25, which is chemical stoichiometric composition, the structural motifs are only SbS3 pyramid and GeS4 tetrahedra, and the three-coordinated SbS3 pyramid is isolated by GeS4 tetrahedra; (2) at x < 0.25, the S- S bonds exist in the glass network due to the excess of S; and (3) at x > 0.25, the excess of Sb break the Ge- S and Sb- S bonds to form Sb( Ge)- Sb Bonds, and the Sb atoms segregate from the backbone to nucleate a separate Sb-rich phase. This work provides a new way to investigate the phase separation of glass networks and helps us to better understand their related physical properties. [ABSTRACT FROM AUTHOR]

In this study, convex microlens arrays (MLAs) on chalcogenide glass (ChG) surface were fabricated through femtosecond laser direct writing and precision molding. Femtosecond laser writing was first employed to induce regularly arranged damage craters on the surface of silica glass. Then, the surface of silica was etched with hydrofluoric acid to obtain a smooth concave MLA. Finally, the concave microlens of silica was replicated on the surface of ChG by precision molding to obtain ChG MLA. The resulting ChG MLA had a uniform structure, clear image, and good focusing effect. By optimising the parameters of laser direct writing and chemical etching, we produced 1600 rectangular and hexagonal microlenses from As 2 Se 3.The optical performances of MLAs were demonstrated by their excellent imaging and focusing capabilities. The method applied provides an efficient way to prepare large-scale MLA masks and MLAs. [ABSTRACT FROM AUTHOR]

A highly sensitive mid-infrared evanescent wave sensor based on side-polished (SPF) chalcogenide fiber (ChG) was proposed in this work. The optimum optical fiber parameters were determined via numerical simulation by detecting the leakage intensity of evanescent waves from the optical fiber of different polish depths. The SPF remarkably enhanced the evanescent wave sensing while maintaining fiber loss and strength. Graphene oxide (GO) was coated on the fiber to enhance the sensitivity of SPF sensor for butane (C 4 H 10). GO has a great specific surface area and abundant oxygen-containing functional groups, which enlarges the contact area of GO with gas molecules and enables to adsorb gas. Results show that the GO-SPF sensor can be three and five times more sensitive than the original fiber optic sensor and SPF sensor for butane gas detection, and has a fast response time and good repeatability. [ABSTRACT FROM AUTHOR]

Te-based glasses are ideal material for life detection and infrared-sensing applications because of their excellent far-infrared properties. In this study, the influence of Ag- and AgI- doped Te-based glasses were discussed. Thermal and optical properties of the prepared glasses were evaluated using X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy. Results show that these glass samples have good amorphous state and thermal stability. However, Ge–Ga–Te–Ag and Ge–Ga–Te–AgI glass systems exhibit completely different in optical properties. With an increase of Ag content, the absorption cut-off edge of Ge–Ga–Te–Ag glass system has a red shift. On the contrary, a blue shift appears in Ge–Ga–Te–AgI glass system with an increase of AgI content. Moreover, the transmittance of Ge–Ga–Te–Ag glass system deteriorates while that of Ge–Ga–Te–AgI glass system ameliorates. All glass samples have wide infrared transmission windows and the far-infrared cut-off wavelengths of these glasses are beyond 25 μm. The main absorption peaks of these glasses are eliminated through a purifying method. [ABSTRACT FROM AUTHOR]

• Together with mechanical milling and SPS method, we fabricated Ge 40 As 40 Se 20 glasses and studied their optical transmission and Vickers hardness. • With ball milling time of 50 h and sintering pressure of 37.5 MPa, an optimal Ge 40 As 40 Se 20 sintered glass with large Vickers hardness of 369 kgf/mm2 and high transmission of ∼43 % was obtained. • The size and number of pores presented in sintered glasses significantly affect the infrared transmission. In order to overcome the narrow glass-forming compositional range with traditional melt-quenching method, we here performed the mechanical milling and Spark Plasma Sintering technology to fabricate a high Ge content chalcogenide glass, the Ge 40 As 40 Se 20 glass, which locates edge of the Ge-As-Se glass-forming domain. By using the optimal ball milling time of 50 h and sintering stress of 37.5 MPa, the large size Ge 40 As 40 Se 20 bulk glasses were obtained, which possesses both a large Vickers hardness of 369 kgf/mm2 and a relative high infrared optical transmission of 43 % (@5 and 9 μm). Moreover, it was found there are pores in the sintered glasses more or less, and the pore size and number significantly affect the transmission, i.e., the optimal Ge 40 As 40 Se 20 bulk glasses were demonstrated has the smallest and least pores via scanning electron microscope. The combination of mechanical milling and low-temperature sintering methods has been confirmed can be used to improve the glass formability and then obtain the high Ge content component with a potential high hardness glass to break through the limited mechanical property of chalcogenides. [ABSTRACT FROM AUTHOR]

In present work, we discovered that nano-crystallization behavior of Ge–S binary chalcogenide glass can be remarkably improved by incorporating trace amount of CsCl as nucleating agent. After implementing an annealing process, the resultant Ge-S-CsCl chalcogenide glass ceramics (GSC ChGCs) possess fine distribution of crystallites belonging to GeS 2 and GeS mixture phase which could enhance mechanical strength and narrow bandgap energy of the original glass. By utilizing femtosecond Z-scan method, nonlinear optical properties of the GSC ChGCs were investigated in a spectral range from 750 to 900 nm. The results showed that the nonlinear absorption attribute of the GSC ChGCs can be enhanced by the crystallinity increase which led to the maximum two-photon absorption coefficient of 19.57 cm/GW at excitation wavelength of 750 nm, increased by 78% as compared to the original glass. This indicates the current GSC ChGCs a promising candidate for the optical limiting devices. [ABSTRACT FROM AUTHOR]

In this study, a novel Te-based glass system was investigated. Some properties of Ge–Ga–Te–NaI chalcogenide glasses such as physical, thermal and optical transmitting were discussed. XRD patterns show this glass system with best amorphous state can dissolve content of NaI as much as 35 at.%. The lowest cut-off wavelength of glass samples is 1645 nm which is the smallest wavelength among the reported Te-based glasses doping with halide. DSC curves indicate that all glass samples have good thermal stabilities (Δ T > 100 °C) and the highest Δ T value corresponding to (Ge 15 Ga 10 Te 75 ) 85 (NaI) 15 glass is 120 °C which is 8 °C greater than that of Ge–Ga–Te host glass. The infrared spectra manifest Ge–Ga–Te–NaI chalcogenide glass system has a wide infrared transmission window between 1.6 μm and 20 μm. Consequently, Ge–Ga–Te–NaI glasses can be a candidate material for far infrared optic imaging and bio-sensing applications. [ABSTRACT FROM AUTHOR]

Chalcogenide glasses (ChGs) excellent optical materials in the infrared range. ChG lens has important applications in the environmental detection and biochemical imaging field. In this paper, microlens arrays (MLA) with good optical quality were prepared by wet-etching assisted femtosecond laser direct writing technology and 2300 microlenses were prepared in the range of 1 mm2. By controlling the power of laser direct writing and the time of chemical etching, microlenses with diameters ranging from 15 to 70 μm could be prepared. An uniform dense stacked MLA with a small volume in the wavelength range of 0.6–12 μm was achieved. The fabricated MLA has a broad application scenario in cutting-edge mid-infrared fields, due to their tiny size, light weight, high integration, and excellent optical quality. [ABSTRACT FROM AUTHOR]

• Chalcogenide glass microlens arrays were fabricated by femtosecond laser-assisted chemical etching method. • By adjusting the laser focusing position, infrared microlens arrays with variable numerical aperture can be obtained. • The multifocal microlens array with multiple focal planes were obtained, which can provide a wider field of view. Infrared microlens arrays (IR MLAs) are high-performance optical devices widely used in various applications such as surveillance, medical, industrial and military fields. However, conventional IR MLAs have a single focal plane, which has limitations in capturing targets at different locations. To solve this problem, this paper proposed a method of preparing multi-focal chalcogenide glass (ChG) MLAs using femtosecond laser-assisted chemical etching. The impact of femtosecond laser energy, pulse number and laser focusing position on microlens size, focal length and numerical aperture (NA) were systematically studied. By optimizing the preparation process, multi-focal MLAs with three different focal lengths of −28.3, −25.96, and −21.3 μm were achieved on Ge-As-S glass, which were tested to have good imaging and focusing effects. Moreover, IR MLAs with NA ranging from 0.52 to 1.15 were obtained by adjusting the laser focus positions. Therefore, the preparation method of MLAs proposed in this work has great flexibility and application potential. [ABSTRACT FROM AUTHOR]

The confinement of CsPbX 3 (X = Cl, Br, and I) perovskite nanocrystals (NCs) in a stabilized inorganic glass matrix is a new strategy for improving their long-term stability and promoting their applications in the optoelectronic field. Here, in situ nanocrystallization strategy is developed to precipitate CsPbBr 3− x I x NCs with arbitrary I/Br ratio among an elaborately designed GeS 2 –Sb 2 S 3 -based chalcogenide glass matrix. Spherical CsPbBr 3− x I x NCs are homogeneously distributed in the glass matrix after thermal treatment. The photoluminescence (PL) spectra show that the emission peaks of CsPbBr 3− x I x NCs can be tuned from 570 nm to 722 nm with the replacement of Br by I. The fs transient absorption (TA) spectra reveal that there exists some structural defects in the NCs, leading to short PL decay life. This work would shed light on confining CsPbX 3 NCs into glassy matrices, facilitating their future applications in photoelectronic fields. [ABSTRACT FROM AUTHOR]

The nonlinear optical properties of metal halide perovskites (MHP) are highly attractive, making them an emerging hotspot in the field of perovskite photonics. In this study, the third-order optical nonlinear properties of lead-free MHP (CsSnCl 3) nano-crystals (NCs) embedded in a chalcogenide glass (GeS 2 -Sb 2 S 3) substrate were characterized using the Z-scan technique. The spectral range examined was from 750 to 900 nm. Experimental results revealed that the incorporation of CsSnCl 3 NCs enhanced the nonlinear refraction and nonlinear absorption behavior of the GeS 2 -Sb 2 S 3 glass. Furthermore, the magnitude of these effects increased with the growth size of the CsSnCl 3 NCs. Importantly, the MHP glasses exhibited strong two-photon absorption due to the large multiple-absorption cross-section of MHP crystals and the intrinsic high optical nonlinearity of the chalcogenide glass. The superior optical limiting performance induced by this process was successfully demonstrated. [Display omitted] [ABSTRACT FROM AUTHOR]

The glass-forming ability, crystallization behavior and physical properties of GeS 2 -Sb 2 S 3 -CsX (X = Cl, Br, I) glasses and glass-ceramics (GCs) are systematically studied by various characterization techniques. With the introduction of cesium halides, transparent chalcogenide GCs containing the single nanocrystals of CsX can be obtained in a controlled fashion. The crystallization behavior was investigated in the line of (100- x) (0.5GeS 2 -0.5Sb 2 S 3)- x CsX glasses. IR-transmitting chalcogenide GCs embedded with CsCl and CsBr nanocrystals of a large crystallinity have been fabricated successfully after thermal treatments, whereas surface crystallization of CsI is dominated in GeS 2 -Sb 2 S 3 –CsI glassy samples. Such distinct crystallization behaviors of CsX crystal phases are compared and discussed with microstructural results. We propose that the ionic diffusion ability of halogen in the GeS 2 -Sb 2 S 3 -CsX glassy network determines the nucleation and crystal growth of CsX. This finding is of guidance meaning for future design of chalcogenide GCs with novel optical functions and microstructures. [ABSTRACT FROM AUTHOR]

Chalcogenide photonic devices are widely used in the detection of harmful substances in solutions; thus, their stability in aqueous solutions is very critical. In this work, the aqueous corrosion behaviors of commonly used chalcogenide glasses (ChGs) were studied at different temperatures and duration. Optical transmission spectra show that the durability of ChGs is greatly affected by glass composition corrosion, solution temperature, and corrosion time. In addition, Se-based glasses are less stable in aqueous solution and will form nanoparticles of pure Se component on the outer surface of samples, which will contribute to the loss of optical transparency. However, Se-nanostructured materials, such as nanowires, can be obtained by carefully controlling the corrosion process and used for the self-assembly of multi-scale devices. The results show that water is a good solvent for the growth of Se nanowires in the liquid phase. This study provides a new way for the production of Se nanowires. [ABSTRACT FROM AUTHOR]

• TONL properties of pristine Ge-Ga-S glasses show high flexibility via composition modification. • TONL parameters of Ge-Ga-S glasses is sensitive to the type of defective units present in glass network. • TONL dispersion of Ge-Ga-S glasses deviates from the classic theories based on semiconductors. In this work, we present a systemic study with respect to the third-order optical nonlinear (TONL) features of chalcogenide glasses (ChGs) within a germanium-gallium-sulfur (Ge-Ga-S, GGS) ternary system. The research outcomes show that the TONL attributes of GGS ChGs are highly tunable by glass composition, and the flexibility is higher than many other reported ChG systems. We have found that the TONL attributes of GGS ChGs depend remarkably on the deviation level of glass composition from chemical stoichiometry, which is associated with the presence of different types of defective units in the GGS glass network. The TONL dispersion of GGS ChGs is discovered to deviate from the classic theories based on crystalline semiconductors, as a result of the presence of multiple-steps absorption process occurred between gap states near the band gap, which renders the GGS ChGs applicable for various types of nonlinear optical functionalities. [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, the finite difference eigenmode approach was used to conduct a theoretical investigation and analysis of the chalcogenide slot waveguide. Maximum power confinement factors of 36.3 % and 56.7 % were found for the slot and cladding areas, respectively. The bidirectional eigenmode expansion approach was then used to develop the chalcogenide slot Bragg grating (SBG) sensor, which was manufactured by electron beam lithography and inductively coupled plasma etching. The chalcogenide SBG has a minimum feature size of 150 nm, which makes it easier to manufacture than silicon photonics Bragg grating devices. Measurement results show a high sensitivity of 325 nm/RIU compared to the conventional evanescent field waveguide sensor in the sensing experiment. [ABSTRACT FROM AUTHOR]

Chalcogenide glass in molar composition of Ga 10 Ge 25 S 65 (GGS) and same glasses doped with various amount of gold were prepared. Both density and refractive index of the glasses increased with increase of gold content. Optical band gap ( E opg ) of the GGS glasses was obtained by Tauc and Menth's method, and the E opg value decreased with increase of gold content. Analysis of Raman spectra informed that the main frame of the glasses was constructed by [GeS 4 ] tetrahedra and no characteristic band belonging to gold was observed, indicating that gold behaved as a glass modifier for the GGS glasses. To investigate the influence the gold has on third-order optical nonlinearities of the GGS glasses, femtosecond Z-scan measurements were conducted at the wavelength of 800 nm. The results showed that the performance of third-order optical nonlinearities of the GGS glasses was improved by introduction of gold. [ABSTRACT FROM AUTHOR]

In this study, we examined the function of halogen iodine acting as a glass network modifier in green chalcogenide glasses based on the Ge–S system. We obtained a series of Ge–S–I glasses and determined their glass-forming region. We then recorded the physical, thermal, and optical properties and studied the effect of halogen iodine on Ge–S–I glasses. Results show that these glasses have relatively wide optical transmission window for infrared (IR) applications. The softening temperature of Ge–S–I glasses varies from 210.54 °C to 321.63 °C, this temperature fits well with some kinds of high-temperature polymers, such as PES and PEI, the polymers serve as protective layers with high strength and flexibility, thus simplifying the fabrication processes of IR chalcogenide glass fiber. Finally, we performed a purification process to eliminate impurities and to improve optical spectra. [ABSTRACT FROM AUTHOR]

• UHMWPE based flat plates were fabricated by Hot Uniaxial Pressing method for long-wave infrared imaging. • Both hot-pressing temperature and cooling rate could affect the transmittance of polymeric flat plate in LWIR spectrum. • The ultrahigh transmittance of 77 % (@ 10.5 μm) can be derived from 0.5 mm thick UHMWPE based flat plate. Although the numerous advantages of germanium or chalcogenide glasses have been applied in the long-wave infrared (LWIR) imaging (8–12 μm), the organic materials with low-cost and easy-fabrication advantages also received widespread attention in recent years. One thing that should be mentioned is that nearly all organic-based materials exist the abundance of vibrational absorptions within the 8–12 μm spectral region. Ultra-High Molecular Weight Polyethylene (UHMWPE) exhibits simplified LWIR spectrum in 8–12 μm due to the presence of only single-bonded carbon and hydrogen -(CH 2) n -. In this paper, we prepared UHMWPE based flat plates by Hot Uniaxial Pressing (HUP) method. Therein, the effects of hot-pressing temperature and cooling rate on the transmission were investigated to find that the transmission is close to the crystallinity of the polymeric flat plate. We optimized an UHMWPE based flat plate with ultrahigh transmittance (∼77% @ 10.5 μm), which was fabricated at the hot-pressing temperature of 190 °C with the cooling rate of 1 °C min−1. The ultrahigh transmittance of the polymeric flat plate, which was obtained from low-cost UHMWPE and easy-fabrication of HUP, makes it be a candidate for LWIR imaging. [ABSTRACT FROM AUTHOR]

Abstract: Rare-earth-ion doped chalcogenide glass is a promising material for developing mid-infrared light sources. In this work, Tm3+-doped chalcogenide glass was prepared and photonic crystal structures were designed to enhance its fluorescence emission at approximately 3.8μm. By employing the finite-difference time-domain (FDTD) simulation, the emission characteristics of the luminescent centers in the bulk material and in the photonic crystals were worked out. Utilizing analysis of the photon excitation inside the sample and the photon extraction on the sample surface, it was found that fluorescence emission can be significantly enhanced 260-fold with the designed photonic crystal structure. The results of this work can be used to realize high-efficiency mid-infrared light sources. [Copyright &y& Elsevier]

Highlights: [•] A minimum losses of 0.037dB/mm at 12μm are obtained in the Te-chalcogenide glass. [•] The absorption band of impurity Ga–O at 15–20μm was eliminated perfectly. [•] A cut-off based method to measure the bulk glass loss was proved effectively. [Copyright &y& Elsevier]

Highlights: [•] Glass formation of Ge–S–Pb system is determined. [•] The effect of the introduction of Pb on the glass structure and physic-chemical properties are investigated. [•] Some micro-crystal glasses formed in quenching procedure exhibit improved mechanical properties and excellent IR transmission. [•] • The effect of Pb addition on the structure-property relationship is investigated. [•] Some crystallized glasses exhibit superior properties. [ABSTRACT FROM AUTHOR]

Abstract: In order to develop novel far infrared window material, a series of Ge–Ga–Te–ZnI2 chalcohalide glasses were prepared by traditional melt-quenching method and their glass-forming region was determined also. Here, some measurements including X-ray diffraction (XRD), differential thermal analysis (DTA), UV–Vis–NIR absorption spectrum, and infrared optical transmission spectra were carried out. The allowed indirect transition optical band gap was calculated according to the classical Tauc equation. The results show that with the addition of ZnI2, the glass-forming ability and thermal stability are improved gradually. With the contents of ZnI2 increased from 5 to 20at.%, continued blue-shifting occurs in the cutting-off absorption edge of short-wavelength and the values of indirect optical band gaps were observed with ranges from 0.596 to 0.626eV in these glasses. These GeTe4.3–GaTe3–ZnI2 glasses show wide optical transmission and the infrared cut-off wavelengths are larger than 25μm, which implies that the Ge–Ga–Te–ZnI2 chalcogenide glasses possess the potential of far-IR optical window applications. [Copyright &y& Elsevier]

Abstract: We report on the fabrication and optical properties of Ge20Sb15Se65 chalcogenide glass rib waveguides on a single photonic chip. Radio-frequency magnetron sputtering method is employed to deposit 1.36-μm-thick films and reactive ion etching with CHF3 is used to pattern 0.76-μm-deep rib waveguides of 1–4 μm wide with low surface roughness and vertical sidewalls. Using lensed fibers, the insertion losses for rib waveguides of different widths are measured and propagation losses are estimated to be lower than 1 dB/cm. Finite difference method simulations and refractive index/curve fitting are used to observe a moderate normal dispersion of the waveguides at 1550 nm. [Copyright &y& Elsevier]

Abstract: Thin films of Ge x Ga5S(95− x ) (x =25, 30, 35) prepared by melt quenching technique were deposited on glass slides by thermal evaporation technique under vacuum. A surface profiler was employed to characterize the morphology of the thin films. Optical transmission spectra measured by a UV/VIS/NIR spectrometer, in the spectral range from 400 to 2500nm, have been used to determine the refractive index, with Swanepoel's method. The thicknesses of the films were calculated with good accuracies better than 1.06%. It has been found that the refractive index of the Ge x Ga5S(95− x ) samples increases with increasing ratio of Ge/S. Optical band gaps were calculated from Tauc's extrapolation procedure and were found to decrease from 2.8eV to 2.59eV with x increasing from 25 to 35. The structural units of the films were characterized by Raman spectroscopy, indicating that in addition to the basic structural units of edge-shared and corner-shared Ge(Ga)S4 tetrahedra, there are S–S homopolar bonds in S-rich films, and the main band of the films slightly shifted to higher frequency and broadened as the ratio of Ge/S increased. The behavior of refractive index and optical band gap were interpreted in terms of structural change of atoms involved in the thin films. [Copyright &y& Elsevier]

Highlights: [•] The glass-forming region of Te-based glasses was enlarged after Ga and CuI adding. [•] With the help of Ga and CuI, all these glasses have relatively high Tg values (>175°C). [•] Studied glass samples all have wide IR transmission window from 1.8 to 20μm. [ABSTRACT FROM AUTHOR]

Abstract: We deposited Ge28Sb12Se60 chalcogenide films using either thermal evaporation or radio-frequency magnetron sputtering techniques, and then measured their structural and optical properties using various diagnosis tools. The refractive indices of the films were obtained from the transmission spectra based on Swanepoel method, and the optical band gaps were derived from optical absorption spectra using the Tauc plot. Raman and X-ray photoelectron spectra (XPS) were measured and decomposed into several peaks that correspond to the different structural units, and then the evolution of the relative concentrations of the structural units was investigated in order to build up the correlation between the structure and optical properties of the films. It was found that, the films generally possess a large number of Ge2Se6/2, Sb2Se4/2 units and Se–Se bonds, and therefore are relatively higher defective compared with their bulk counterpart. This together with the modification of the chemical compositions results in a higher refractive index as well as a smaller optical band gap in the films. Thermal annealing of the deposited films could convert the optical and structure properties of the films close to those of bulk glass. [Copyright &y& Elsevier]

Abstract: A systematic series of (Ge20Se15Te65)1− x –(SnI2) x (x =0, 0.05, 0.1, 0.15) chalcogenide glasses have been prepared. The amorphous nature can be confirmed by XRD and SEM. With the SnI2 content increasing, the indirect optical band gaps are decreased from 0.662 to 0.622eV according to Tauc laws. The introduction of SnI2 makes the glasses much easier to prepare and more stable against crystallization, making them drawable as optical fibers. The highest ΔT (130°C) value for (Ge20Se15Te65)0.9–(SnI2)0.1 glass composition can be obtained. A slight red-shifting of the long-wavelength cutting-off edge from 18.4 to 19.4μm was shown and it seems that SnI2 in these glasses offers the improvement in the far-infrared properties. [Copyright &y& Elsevier]

• High quality Ge-As-S glass and low loss fibers were prepared. • FZP working in visible and near infrared bands was fabricated on Ge-As-S glasses surface by laser direct writing. • With a well-designed FZP on the fiber end face, ChG fiber can achieve excellent self-focusing effect without the collimating and focusing lens. Chalcogenide glass (ChG) has excellent optical properties in the mid-infrared range. The micro-optical fiber devices made of ChG play a strong part in various infrared sensing and detection fields. In this work, Fresnel zone plate (FZP) was fabricated on the Ge-As-S ChG surface and the end face of ChG fiber through femtosecond laser direct writing. FZP with high optical quality was obtained by optimizing the laser writing parameters. Clear focusing pattern can be observed in the visible and infrared bands with the prepared FZP. The full width at half maximum (FWHM) of laser beam with wavelength of 1550 nm is recorded to be 10.39 μm at the focus of FZP, and the numerical aperture (NA) is 0.122. With a well-designed FZP on the fiber end face, the ChG fiber can achieve a self-focusing effect without the collimating and focusing lens. The FWHM of the 1550 nm laser beam at the focus is measured to be 7.46 μm, and NA is 0.162. The combination of FZP and ChG fiber can make the structure of the optical fiber more compact and has potential application value in enhancing the interaction between light and material in the infrared band. [ABSTRACT FROM AUTHOR]

Novel chalcogenide glasses of the pseudo-binary (100- x)Sb 2 S 3 - x PbI 2 system were synthesized by traditional melt-quenching method, and its glass-forming region was determined from x = 20 to 55 mol%. Compared to traditional sulfide glasses, the long-wave infrared (LWIR) cut-off edge of Sb 2 S 3 -PbI 2 glasses is extended up to 14 μm. The physical properties of these glasses, including their T g , Δ T (= T x − T g), Vickers hardness, density, and Abbe number, were characterized and analyzed using their compositional dependent Raman spectra. [SbI 3 ] structural units could promote the forming ability (Δ T) of the Sb 2 S 3 -PbI 2 glasses because of the broken connectivity of the network structure. The results of this research provide useful knowledge for developing novel LWIR chalcogenide glasses. [ABSTRACT FROM AUTHOR]

We have fabricated Ge 20 Ga 10 S 70 glasses doped with 1.0 at% Er and annealed them to create chalcogenide glass-ceramics. We further characterized their optical transmission, luminescence, and microstructure for investigating the mechanism of the fluorescence enhancement. The results showed that, Ga 2 S 3 and GeS 2 crystals are precipitated successively, the transmittance of the glass-ceramics decreases, and the transmission edge shifts towards longer wavelengths with prolonged annealing time. Photoluminescence (PL) intensity at 1.54 μm in glass-ceramics with 20 h annealing time is twice than that in the base glass. From the similar evolution of PL and XRD intensity, we concluded that the luminescence enhancement is related to the Ga 2 S 3 crystals in glass-ceramics. The Er ions are registered near tht Ga 2 S 3 crystalline grains with a size of 50 nm as evident by elemental mapping. The results are helpful to optimize the chalcogenide glass components doped with REI and improve the solubility of REI. • The luminescence intensity at 1.54 μm in glass-ceramics with 20 h annealing time is twice than that in the base glass. • The luminescence enhancement is related to the Ga 2 S 3 crystals in glass-ceramics. • The Er ions could only be found near the Ga 2 S 3 crystalline grains of elemental mapping. [ABSTRACT FROM AUTHOR]