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International audience; Se with good glass formation ability was gradually doped into the Ge-As-Te glasses, and then the gradual change processes of some key physical and optical properties were observed. A series of Ge10As40Te50-xSex(x=0, 10, 20, 30, 40, 50) chalcogenide glass samples were prepared by the traditional melt-quenching method. The internal microstructure, physical and chemical properties of the glass samples were analyzed by using X-ray diffraction, Raman spectroscopy and thermal dilatometer instruments. Vis-NIR absorption spectra and infrared optical transmission spectra of these glasses were recorded with Spectrophotometer and Fourier transform infrared spectroscopy instrument. Then, the Tauc equation was adopted to calculate the direct and indirect optical band gaps of the glass samples. The results show that with the increasing of the Se, the thermal stability can be effectively improved, the maximum Tg can reach up to 233℃. A obvious blue shift of short infrared absorption spectrum cut-off edge appearance is observed in these glasses, i.e. The optical band gap increases gradually, which shows a wider range of transmission and better transparency spectrum, the maximum transmission rate can reach up to 56%. Infrared cut-off edge remains at 20μm, while Se content is less than 2 mol, its thermal stability is improved obviously and the optical spectral changes little. At last, using metal Mg as an oxide redactor for the purification of these glasses, the results show that the transmission spectra is much smooth and without any obvious impurity absorption peaks after the appropriate purification process. © 2016, Science Press. All right reserved.

Third-order optical nonlinear characterizations of glasses in Bi 2 O 3 –B 2 O 3 –TiO 2 ternary system were investigated using femto-second Z -scan method at 800 nm. Results show that third-order optical nonlinearities are influenced by TiO 2 concentration, the largest value of nonlinear refraction γ obtained is 8.85×10 −14 cm 2 /W. Further, the hyperpolarizability α (3) of Bi–O–Ti 4+ units which is considered to be main contribution to the large third-order nonlinearity is estimated to be 1.32×10 −33 esu cm 3 /unit. Additionally, enhancement of two-photon absorption process near 0.73 E opg is observed.

In this paper, using the self-made Ge20Sb15Se65 chalcogenide glass as matrix material, we design an infrared octagon dispersion flattened photonic crystal fiber, and the mid-IR dispersion and transmission characteristics are numerically studied using the multipole method. Results show that when we control the duty ratio (d/Λ) in 0.323–0.367, the dispersion and transmission properties in the 3–5 μm range are adjustable. When we set the hole spacing Λ=3.4 μm, hole diameter d=1.1 μm, in the 4.1–4.9 μm band, the fiber dispersion fluctuates between-0.8 ps·nm-1·km-1 and 0.8 ps·nm-1·km-1, and shows single-mode transmission, low loss (LossAeff2) characteristics, thus it is suitable for nonlinear applications in mid-IR band.

Large mode area photonic crystal fibers (PCFs) have attracted much attention, owing to their applications in such as high power delivery, high power fibre amplifiers and fiber lasers. As an ideal candidate for fabricating mid-infrared fibers, chalcogenide glass possesses some unique advantages, such as high refractive indices (2.0-3.5), low photon energies (lower than 350 cm-1), tailorable compositions, and large infrared transmission window(from 1.0 to 20 μm). In this paper, we present a novel type of effectively single-mode chalcogenide glass Ge20Sb15Se65PCF with utra-large mode area as well as small confinement loss (lower than 0.1 dB/m for the fundamental mode, high confinement loss exceeding 2 dB/m for the higher-order mode at 10.6 μm).

A novel series of Ge-Te-PbI2 chalcogenide glasses is prepared by traditional melt-quenching method, and the glass-forming region is determined. X-ray diffraction, differential thermal analysis, visible/near-infrared absorption spectroscopy and infrared transmission spectra are adopted to analyze the composition, the structure, and the performance of the Te-based glasses system with an addition of PbI2. The Tauc equation is used to calculate the direct and the indirect optical band gaps, based on the metallization criterion and the band gap energy theory, the relationship between optical band gap and composition is investigated. The results show that with the addition of PbI2, the glasses-forming ability and the thermal stability are improved, Also, the density and the refractive index of glass sample both increase, the short-wavelength edges shift to ward a longer wavelength, the band gap decreases and the infrared cut-off wavelength of glass is 25 m which keeps almost unchanged. The series of glasses can be adopted to fabricate the far-IR optical wave-guide devices.

The tapping temperature and the cooling rate are the key parameters during the development process of chalcogenide glass. Based on the theory of heat conduction equation, a model for calculating the temperature distribution of cylindrical chalcogenide glass is established using the least square fitting method in this paper. The tapping temperature, the temperature distribution and the cooling rate are simulated by using the model. The simulation results are compared with experimental data. The results show that the glass temperature stays in a non-steady non-uniform distribution, the surface cooling is the fastest, and the temperature decreases exponentially with time when the glass is tapped off from the furnace; the temperature of glass rod from the center to the edge is approximately of parabola distribution; the crystallization is the most difficult when the glass is tapped off at 50100 ℃ higher than crystallization temperature and a surface heat exchange coefficient of 180 W m-2K-1. Under the guidance of the theoretical model the uniform and transparent chalcogenide glass with a diameter of 110 mm and height of 80 mm is obtained. The glass transmission spectrum range is 0.817 m. The 2 mm thick flat sheet has the average transmittance higher than 65% in a 812 m range.

A series of chalcogenide glasses based on Ge 25 Ga 10 Se 65 system co-doped with Ho 3+ /Pr 3+ ions of different ratios were synthesized by melt-quenching technique. The absorption spectra,mid-infrared fluorescence and lifetime of glass samples under 908 nm laser excitation were measured. The emission cross section of Ho 3+ : 5 I 7 → 5 I 8 and absorption cross section of Pr 3+ : 3 H 4 → 3 F 2 were calculated. The energy transfer efficiency between Ho 3+ and Pr 3+ ions with different Pr 3+ ion concentrations have been discussed. Through fitting the 2.0 μm fluorescence decay curves of Ho 3+ ions,the energy transfer regime was judged. The results prove thatTm 3+ is an efficient sensitizer which enhances the Ho 3+ : 2.9 μm fluorescence intensity significantly.