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In this work, we successfully prepared gold nanoparticles (AuNPs) within a germanium–tin–sulfur (Ge–Sn–S, GSS) chalcogenide glass (ChG). The formation of AuNPs in the GSS ChG relies on the reduction capacity of Sn2+ ions, which we found their existence in the glass matrix by the characteristic emissions at nearly 450 nm. The AuNPs exhibit strong optical activity which caused a significant enhancement of third-order optical nonlinearity of the GSS ChG as well as photon luminescence of the Sn2+ ions. In addition, optical properties the AuNPs-embedded GSS ChGs can be modified by further gold doping and one-step heat-treatment process. [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]

We reported the fabrication of submicron photonic crystal with AsSeTe chalcogenide glass by resist-free thermal nanoimprint using a soft stamp. The AsSeTe glass was prepared with melt-quenching method, and measured to have broad transmission range, high linear and nonlinear refractive index, and good thermal stability. Due to the very low glass transition temperature, the thermal nanoimprint was accomplished directly on the resist-free bulk glass with the soft stamp. By choosing suitable imprint condition, submicron chalcogenide glass photonic crystal with the band gap covering telecom wavelength was obtained. Taking advantage of the high nonlinearity of AsSeTe glass, the imprinted PC structure may have potential applications for all-optical switch in optical communications. [ABSTRACT FROM AUTHOR]

In this study, a series of GeTeSe ( x = 0, 5, 10, 20, 30, 60, 70) chalcogenide glasses were prepared using conventional melt-quenching technique. Through absorption spectra analysis, the optical Tauc gaps were derived in detail along the increase in the Te content which can be supported by structural changing of glass network shown by Raman spectra. The third-order optical nonlinearity of the glasses at mid-infrared wavelength of 3.1 μm was investigated by traditional Z-scan method. The nonlinear refractive index of the glasses increased with the increase in the Te content, typically the measured nonlinear refractive index of GeSeTe glass increased to 8.2 ± 1.2 × 10 m/W. The relationship between the nonlinear refractive index and the optical band gap was analyzed. [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]

The theoretical analysis and experimental preparation of a hollow-core Bragg fiber based on chalcogenide glasses are demonstrated. The fiber has potential applications in bio-sensing and IR energy transmission. Two chalcogenide glasses with, respectively, high and low refractive indexes are investigated in detail for the fabrication of hollow-core Bragg fibers. The most appropriate structure is selected; this structure is composed of four concentric rings and a center air hole . Its band gap for the Bragg fiber is analyzed by the plane wave method. The chalcogenide glasses GeSbSI and GeSbSe are chosen to extrude the robust multi-material glass preform with a specialized punch and glass container. The glass preform is simultaneously protected with a polyetherimide polymer. The hollow-core Bragg fibers are finally obtained after glass preform extrusion, fiber preform fabrication, and fiber drawing. Results showed that the fiber has a transparency window from 2.5 to 14 μm, including a low-loss transmission window from 10.5 to 12 μm. The location of this low-loss transmission window matches the predicted photonic band gap in the simulation. [ABSTRACT FROM AUTHOR]

The crystallization characteristic, electrical, and optical properties of ZnSb-doped SbTe thin films have been systematically investigated. The results show that the crystalline phase, grain size, and the preferred orientation are influenced by ZnSb addition. Meanwhile, ZnSb doping can effectively increase the thermal stability of SbTe films such as crystallization temperature and crystallization activation energy, and maintain fast crystallization speed. Among ZnSb-doped SbTe films, ZnSbTe film exhibits both shorter complete crystallization time (135 ns at 70 mW) and appropriate thermal stability (keeping the amorphous state at 107.2 °C for 10 years). [ABSTRACT FROM AUTHOR]

In this paper, multilayer TiN/W with interfacial nanostructure is used as electrode for application in low-power phase change memory (PCM). Compared with single-layer electrode, multilayer electrode has much lower thermal conductive due to the interfacial scattering effect. PCM based on multilayer electrode with different thickness ratio of TiN and W was fabricated and characterized. The device properties including operation voltage and endurance depended critically on the multilayer structure rather than the thickness ratio of TiN and W. The low operation voltage and long cycle life of multilayer-electrode-based PCM result from the increase in overall thermal resistance due to the low thermal conductivity of multilayer electrode. [ABSTRACT FROM AUTHOR]

The crystallization behavior of the 70GeS-20InS-10CsI glass introduced with 2 mol% AgS system has been studied under non-isothermal condition. The beginning of transmission is shifted toward longer wavelength as a function of annealing temperature. Thermal properties were measured by the differential scanning calorimeter. From the heating rate dependence of crystallization temperature, the activation energy ( E) for crystallization and the crystallization rate constant ( K) were calculated. The K value of 2.44 × 10 for the InS phase is about 28 times larger than the second CP, this is why the controllable crystallization to transparent chalcogenide glass-ceramics with sole InS crystallites can be achieved. By heat treatment with various temperatures, the hardness of the glass enhanced from 204 to 230.8 kg mm, while retained the transmittance of the 8-11 μm. [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 488 nm continuous wave (CW) laser was employed in Raman spectrometer to both induce and characterize phase transformation in chalcogenide glasses. Laser-induced Raman inactive changes, structural evolution, and crystallization were observed at laser-irradiated region in GeS-SbS glasses. The composition dependence of laser-induced phase transformation was discussed in terms of thermal stability and microstructural modification. It is strongly suggested from these results that fabrication of passive and active chalcogenide glass waveguides, such as refractive index change and nonlinear optical crystal line, is controllable by selecting appropriate glass composition, and convenient by using common CW lasers. [ABSTRACT FROM AUTHOR]

65GeS⋅25InS⋅10CsCl chalcohalide glass-ceramics containing β-InS crystallites in the glassy matrix were prepared by traditional melt-quenching and subsequent heat-treatment at a fairly low temperature ( T+10 C) for different durations. The transmission spectra show that the cut-off edge of short wavelength is red-shifted with the prolongation of annealing time, but remains an excellent transmittance in the mid-IR region. Meanwhile, its crystallization behavior was investigated systematically. The results show that the precipitation of β-InS crystal phase is responsible for the first crystallization peak, and the second crystal phase is GeS, which precipitated in the interior after a heat treatment at a high temperature ( T+70 C). Furthermore, the crystallization mechanism was investigated using the non-isothermal method. The crystallization rate constant K value of 6.08×10 s at 346 C for the β-InS phase is about three times larger than that of the GeS phase, indicating a much easier crystallization mechanism of β-InS phase. Therefore, it is easy to control the precipitation of sole β-InS crystallite, and to avoid interference of the second crystal phase GeS. [ABSTRACT FROM AUTHOR]

The effects of laser irradiation condition and deposition substrate on the laser crystallized 330 nm Si films structure were investigated using in situ micro-Raman spectroscopy. Results showed that crystallization of amorphous silicon (a-Si) films started at laser irradiation power density of 0.6 × 10 W/cm for 20 s. The crystalline volume fraction of Si films depended mostly on the laser power density but not on the laser irradiation time. The Si films on both smooth and textured aluminum-doped zinc oxide (AZO) substrates exhibited lower crystalline volume fraction and smaller average grain size than the Si films on glass did. The Si films on textured AZO revealed higher crystalline volume fraction and larger average grain size than the Si films on smooth AZO did. The stress in crystalline Si films was observed to be compressive on AZO and tensile on glass. The compressive stress in crystalline Si films on textured AZO was slightly less than that on smooth AZO. The present work indicated that the structure of crystalline Si films on textured AZO was improved than that on smooth AZO, which may be helpful to crystalline Si thin-film solar cell. [ABSTRACT FROM AUTHOR]

Transparent 90GeS⋅10GaS(G10) chalcogenide glass-ceramics containing β-GeS nanocrystals was successfully fabricated through controllable crystallization based on the knowledge of its nucleation-rate-like curve. Using the conventional Z-scan method, both large spectral dependence and crystallinity dependence of optical nonlinear parameters were learned under the excitation of different wavelengths that in proximity of the half-bandgap. In particular, a large value of figure of merit (FOM≈11.64) was obtained in the crystallized sample after the heat-treatment at 466°C for 40 h. Although it is not a straightforward process to select an appropriate medium for a specific application, this work opens a new way to construct suitable optical nonlinear properties (e.g., large FOM) though modifying the microstructure of chalcogenide glass-ceramics. [ABSTRACT FROM AUTHOR]

series of glasses with high BiO content of BiO-BO-WO ternary system were chosen and prepared. Their densities and linear refractive indices increase with increasing WO content. The optical band gaps E of glasses obtained from ultraviolet absorption edges decreases with increase of WO content. Z-scan technique was carried out to investigate the third-order nonlinear optical properties of the glasses. It is found that the nonlinear refraction γ increases with decreasing the optical band gap E, since an increase of WO content can promote the non-bridging oxygen ion content, and the highest γ value of samples is 1.173×10 cm/W. The results show that these glasses are potential materials in the application of third-order nonlinear optics field. [ABSTRACT FROM AUTHOR]

Information on cerebral oxygenation during prolonged driving in healthy humans may help to explain the cause and development of central fatigue and its effects on cortex activities. The objective of this study is to investigate the time course of cerebral oxygenation during a prolonged driving task. Forty healthy male subjects were randomly divided into two groups: task group (Task) and control group (CNL). All subjects were required to rest well prior to the experiment. For the task group, subjects were required to perform the simulated driving task for 3 h. Cerebral oxygenation signal was monitored from the left frontal lobe using near infrared spectroscopy throughout the entire experiment. Significant increases in the concentrations of HbO(2) (DeltaCHbO(2)) and HbT (DeltaCHbT) were recorded at the start of driving task compared with the resting value (p < 0.01). The cerebral oxygen saturation in the Task group was found to be significantly lower following three hours of driving compared with that in the CNL (F = 16.95, p < 0.001). In addition, a significant difference in selective reaction time was observed between the Task group and CNL during the post-task period (p = 0.023). The results demonstrated that the cerebral oxygenation is closely related to the mental stress. The decrease in the cerebral oxygen saturation may indicate reduced cerebral oxygen delivery, and this may be an important factor affecting central fatigue development during prolonged driving. [ABSTRACT FROM AUTHOR]

The glass forming region of Bi2O3-B2O3-BaO ternary system was investigated. A serial of glass samples with high Bi2O3 content in Bi2O3-B2O3-BaO system were prepared by using conventional melting and quenching meld, and the refractive indexes and absorption spectra of samples were measured. It is found that the refractive index of samples as well as the UV absorption increase with the increase of BaO content. According to the Tauc law, optical band gap Eopg which is assumed to be the effective energy band gap Eg is calculated and decreases with the increasing BaO content, and the ratio of Eg/ Eopg is 1.3. [ABSTRACT FROM AUTHOR]

Examines the spectral properties of commercial ytterbium doped phosphate laser glass. Measurement of refractive index with V-prism; Usability of x-ray powder diffraction and laser tomography; Reduction of the effects of radiation trapping.

Two kinds of step-index As-S fibers have been fabricated by an isolated extrusion method with a numerical aperture (NA) of 0.52, but with different core size of 10 or 50 µm. With a femtosecond laser pumping, their supercontinnum (SC) generation spectra were recorded in order to testify the effect of high-order modes on SC generation. The spectra spanning from 1.0 to 6.7 µm and from 1.5 to 8.6 µm can be obtained in a 16-cm-long fiber with 10 µm-core diameter pumping by central wavelength of 2.9 and 4.0 µm, respectively. The results show that high-order modes would deplete the spectra spanning in red-shifting part. The SC generation in small-core fiber is much more efficient than that in large-core fiber. This is the first comparative investigation on the SC generation from the quasi single- and multi-mode ChG fibers under the same conditions. [ABSTRACT FROM AUTHOR]

Compared with the traditional fluoride fibers and tellurite fibers that can work in the near-infrared region, suspended-core fibers based on chalcogenide glasses have wider transmitting regions and higher nonlinear coefficients, thus the mid-infrared supercontinuum generations can be achieved easily. Rather than adopting the traditional fabrication technique of hole-drilling and air filling, we adopted a totally novel extrusion technique to fabricate As2S3 suspended-core fibers with four holes, and its mid-infrared supercontinuum generation was investigated systematically by integrating theoretical simulation and empirical results. The generalized nonlinear SchrÖdinger equation was used to simulate the supercontinuum generation in the As2S3 suspended-core fibers. The simulated supercontinuum generation in the As2S3 suspended-core fibers with different pump wavelengths (2-5 µm), increasing powers (0.3-4 kW), and various fiber lengths (1-50 cm) was obtained by a simulative software, MATLAB. The experimental results of supercontinuum generation via femtosecond optical parametric amplification (OPA) were recorded by changing fiber lengths (5-25 cm), pump wavelengths (2.9-5 µm), and pump powers (10-200 kW). The simulated consulting spectra are consistent with the experimental results of supercontinuum generation only if the fiber loss is sufficiently low. [ABSTRACT FROM AUTHOR]

CdSe quantum dots (QDs) doped glasses have been widely investigated for optical filters, LED color converter and other optical emitters. Unlike CdSe QDs in solution, it is difficult to passivate the surface defects of CdSe QDs in glass matrix, which strongly suppress its intrinsic emission. In this study, surface passivation of CdSe quantum dots (QDs) by Cd1−xZnxSe shell in silicate glass was reported. An increase in the Se/Cd ratio can lead to the partial passivation of the surface states and appearance of the intrinsic emission of CdSe QDs. Optimizing the heat-treatment condition promotes the incorporation of Zn into CdSe QDs and results in the quenching of the defect emission. Formation of CdSe/Cd1−xZnxSe core/graded shell QDs is evidenced by the experimental results of TEM and Raman spectroscopy. Realization of the surface passivation and intrinsic emission of II-VI QDs may facilitate the wide applications of QDs doped all inorganic amorphous materials. [ABSTRACT FROM AUTHOR]

Gallium-based Ga-Sb-S sulfide glasses was elaborated and studied. A relationship between the structure, composition, and optical properties of the glass has been established. The effects of the introduction of Ga on the structure using infrared and Raman spectroscopies and on the Er3+-doped IR emission have been discussed. The results show that incorporation of Ga induced the dissociation of [SbS3] pyramids units and the formation of tetrahedral [GaS4] units. The dissolved rare earth ions are separated around the Ga-S bonding and the infrared emission quenching are controlled. Moreover, continuous introduction of Er ions into the glass forms more Er-S bonds through the further aggregation surrounding the [GaS4] units. In return, the infrared emission intensity decreased with excessive Er ion addition. This phenomenon is correlated with the recurrence concentration quenching effect induced by the increase of [GaS4] units. [ABSTRACT FROM AUTHOR]

Chalcogenide glass has been considered as a promising host for the potential laser gain and amplifier media operating in near- and mid-IR spectral region. In this work, the IR luminescence spectra of rare earth ions (Tm3+, Er3+, and Dy3+) doped 65GeS2-25In2S3-10CsI chalcogenide glasses were measured under the excitation of an 808 nm laser diode. To the best of our knowledge, it firstly provides the luminescence spectra of a full near- and mid-IR spectral range from 1 to 4 μm in rare earth ions doped chalcogenide glasses. The results of absorption spectra, luminescence spectra, and fluorescence decay curves were obtained in these samples with singly-, co- and triply-doping behaviors of Tm3+, Er3+, and Dy3+ ions. In order to search possible efficient IR emissions, the luminescence behavior was investigated specifically with the variation of doping behaviors and dopant ions, especially in the samples co- and triply-doped active ions. The results suggest that favorable near- and mid-IR luminescence of rare earth ions can be further modified in chalcogenide glasses through an elaborated design of doping behavior and optically active ions. [ABSTRACT FROM AUTHOR]