•The influences of draw processing parameters on CHG fiber quality are systematically investigated.•A very little amount of crystals on As2Se3 fiber surface are precipitated in case of unsuitable drawing process.•Results of this work will provide practical guidance for CHG fiber drawing processes.As2Se3 glass fibers measuring 250 μm in diameter were fabricated based on different draw processing parameters, including preform dropping temperatures (T1 = Tg + ΔT, ΔT = 20, 30, 40, 50 °C), fiber-drawing temperatures (T2 = Tg + ΔT, ΔT = 10, 20, 50 °C), and drawing speeds. Raman spectra indicated crystallization on fiber surface at high temperatures. After fiber drawing, oxygen was detected on fiber surface by energy dispersive X-ray spectra. High-quality fiber with minimum loss of 1.88 dB/m (at 9.05 µm) was achieved under optimal dropping temperature of 218.1 °C (Tg + 30 °C), fiber-drawing temperature of 208.1 °C (Tg + 20 °C), and drawing speed of 0.10 m/min.

•The polishing process for end surfaces of ChG glass fiber were in detail investigated, the effects of polishing parameters were analyzed and the polishing parameters were determined.•The ChG fiber connector with high quality and good practical applications between ChG fibers and traditional silica fiber were fabricated.We have investigated the optimization parameters for polishing end-surface of chalcogenide glass fiber connector in the paper. Six SiC abrasive particles of different sizes were used to polish the fiber in order of size from large to small. We analyzed the effects of polishing parameters such as particle sizes, grinding speeds and polishing durations on the quality of the fiber end surface and determined the optimized polishing parameters. We found that, high-quality fiber end surface can be achieved using only three different SiC abrasives. The surface roughness of the final ChG fiber end surface is about 48 nm without any scratches, spots and cracks. Such polishing processes could reduce the average insertion loss of the connector to about 3.4 dB.

A series of Pr3+-doped selenide glasses was prepared by a melt-quenching method. The Pr3+ doped fibre optic preform was fabricated using extrusion and was successfully drawn into a low optical loss, step-index fibre. Intense mid-infrared (2.8–5.5 μm) fluorescence spectra were achieved at different concentrations of Pr3+ doped selenide glass with a pump of 2.0 μm. A comparison of the emission spectra of bulk glass and the fibres is presented under 2.0 μm wavelength excitation. The strongest emission was achieved due to the dispersion effect of Ga by forming bonds of Pr3+–Se–Ga. Based on the measured absorption spectra, the Judd–Ofelt parameters were calculated, discussed and compared with other host glasses. Given these properties, this system has the potential to be a good gain material for further development to realize both fibre lasers and amplified spontaneous emission fibre sources in the mid-infrared region.

•Mechanical drilling method was developed to fabricate chalcogenide glasses PCFs.•PCFs with unregularly structures can be prepared with mechanical drilling.•Mechanical drilling can reduce the inhomogeneities at the interfaces of the PCFs.A mechanical drilling method for the preparation of photonic crystal fibers (PCFs) is presented in this paper. Several PCFs were fabricated with Ge20Sb15S65 chalcogenide glasses, which have high transparency in the mid-infrared (IR) range. The mechanical drilling method has been identified as a powerful tool to prepare fibers with a variety of structures and to increase the transmission of the obtained fibers. For a three-ring PCF, the near-field intensity distribution and the transmission loss were measured. It was found that most of the optical energy is contained in the core of the PCF. The profile of the near-field intensity image shows that the prepared PCF can work with a large mode area, which is important in high-power laser propagation and fiber amplifiers.

Glass-forming region of Bi2O3–GeO2–TiO2 (BGT) pseudo-ternary system was determined by using melt-quench method. A series of high transparent glass samples were selected and their structural characteristics were investigated by FT-IR and Raman spectra. By employing Z-scan and optical Kerr shutter techniques with femtosecond laser pulses as excitation source, third-order optical nonlinearities (TON) of the BGT glasses as well as the TON response time were investigated at wavelength of 800 nm. The ultrafast nonlinear response and high figure of merit suggest great potentials of BGT glasses in applications of all-optical switching or related optical devices.Highlights► Glass-forming region of novel Bi2O3–GeO2–TiO2 system is determined. ► Increase of TiO2 or Bi2O3 content in BGT glasses promoted third-order optical nonlinearities. ► BGT glasses show ultrafast third-order nonlinear response time (<200 fs).

Structural order beyond the next-nearest-neighbor structural units is of great interest in network glasses, especially in chalcogenide glasses, but little specific description can be reached. Here, the structure of pseudobinary (100 – x)GeS2–xSb2S3 chalcogenide glasses is elucidated using differential scanning calorimetry, Raman scattering, and laser-induced phase transformation experiments over its full range (0 ≤ x ≤ 100) of compositions. We observe two compositional thresholds of x = 40 and 50 in the calorimetric experiments, which are confirmed by Raman scattering and laser-induced phase transformation studies, respectively. Three structural features can be derived from these results: the structural motifs in this glass network are the [SbS3] pyramid and [GeS4] tetrahedra, respectively; at x ≥ 40, the connection between [GeS4] tetrahedra vanishes; and at x ≥ 50, the aggregation of four [SbS3] units happens, preparing for the laser-induced crystallization of Sb2S3 crystallites. Combined with valuable indication from the topological thresholds, a specific structural model covering the arrangement of structural units in a large atomic scale is clarified, which can perfectly explain all the experimental results. This work provides a new way to get insight into the intermediate-range order of glass networks and understand their related physical properties.

Chalcohalide glass with a composition of 65GeS2–25Ga2S3–10CsI (in mol%) doped with 0.6 wt% Tm3+ ions was prepared by conventional melt–quench method. By heat treating the precursor glass at 20 °C above its glass transition temperature Tg for different durations, IR transparent glass ceramics were obtained. X-ray diffraction (XRD) and scanning electron microscope (SEM) showed that Ga2S3 crystallites were precipitated after heat treatment and their grain sizes were in nano-scale and increased with the elongation of heat treated time. Mid-IR luminescence properties of the glass and transparent glass ceramic samples were investigated. The emissions at 2.3 and 3.8 μm corresponding to optical transitions of 3H4 → 3H5 and 3H5 → 3F4 of Tm3+ ions were significantly enhanced by the presence of Ga2S3 nanocrystals and reached a maximum after 8 hours treatment.

Surface plasmon resonance (SPR) of noble metal nanoparticles (NPs) fostered a new area of nanophotonics, especially in the selective photon absorption and scattering. The precipitation of Ag NPs in glass would enhance the emission efficiency. Here, we studied the effects of annealing temperature (resulted in the increased Ag NPs’ concentration) or AgCl concentration on the luminescence properties of Er3+/Yb3+ codoped bismuth-germanate glasses which were synthesized by a single-step melting–quenching technique. The SPR peak of Ag NPs appears around 600 nm, and the size of precipitated Ag NPs (spherical, hexagonal) ranges from 5 to 15 nm. With the precipitation of the Ag NPs, more intense green (527 nm, 548 nm) and red (661 nm) upconversion (UC) emission bands are observed up to 7.7, 10.1, and 6.5 folds in the glass containing 1 wt % AgCl annealed at 480 °C for 24 h, respectively. The Ag NPs embedded glasses showed significantly local field change that allowed for more bright UC emission by SPR.

Serials of chalcogenide glasses based on composition of 72GeS2–18Ga2S3–10CsI (in mol%) and doped with high Tm3+ content (up to 10,000 ppm) were prepared, and their luminescence properties were investigated under excitation with 800 nm laser. The influences of doping concentration on Judd–Ofelt intensity parameter Ωi, spontaneous transition probability A, fluorescence branching ratio β, and radiative lifetime τrad of Tm3+ in the samples were studied. Four infrared emission bands observed were centered at 1.48, 1.8, 2.3, and 3.8 μm, corresponding to optical transitions 3H4 → 3F4, 3F4 → 3H6, 3H4 → 3H5 and 3H5 → 3F4, respectively. For 1.0 wt.% Tm3+: doped sample, no concentration quenching was observed and its emission cross-sections at 2.3 and 3.8 μm calculated by using Füchtbauer–Ladenburg equation were 6.85 × 10−21 and 7.66 × 10−21 cm−2, respectively.

The ternary of TeO2–Nb2O5–Bi2O3 glass was prepared using conventional melt-quenching method and formation range of TeO2–Nb2O5–Bi2O3 glass system was investigated. The physical and optical properties (density, refractive index, molar volume, glass temperature transition (Tg), crystallization temperature (Tx), optical absorption and energy gap) were determined. The glasses have high refractive indexes, which are more than 2.0. The largest refractive index value 2.1927 at 632.8 nm was obtained for 75TeO2–10Nb2O5–15Bi2O3 glass. The 85TeO2–10Nb2O5–5Bi2O3 glass has a high enough difference, ΔT (between Tg and Tx) (155 °C). Direct allowed transition (Eopt) and indirect allowed transition of samples were calculated according to classical Tauc equation. It is found that the addition of Nb2O5 and Bi2O3 to TeO2 glass increases the refractive index value as well as density, whereas the TeO2–Nb2O5–Bi2O3 glass system has small domain. The refractive index of the glasses increases with increasing molar volume, tendency for small energy band gap, optical band gap and metallization criterion.

A series of tellurite glasses of composition, 75TeO2–20ZnO–(5 − x)La2O3–xEr2O3 (x = 0.05, 0.1, 0.3, 0.6, 1.0, 2.0, and 3.0 mol%) with different hydroxl content were prepared. The effect of Er3+ and OH− groups concentration on the emission properties of Er3+: 4I13/2 → 4I15/2 transition in tellurite glasses was investigated. The constant KOH–Er for Er3+ in tellurite glasses, which represents the strength of interaction between Er3+ and OH− groups in the case of energy migration, was about 14 × 10−19 cm4 s−1. The interaction parameter CEr,Er for the migration rate of Er3+: 4I13/2 → 4I13/2 transition in tellurite glass was 46 × 10−40 cm2, which indicates that concentration quenching in Er3+-doped modified tellurite glass for a given Er3+ concentration is much stronger than in silicate and phosphate glasses.

The effect of radiation trapping on the emission properties of Er3+-doped tellurite and phosphate glasses has been investigated as the function of sample thickness and doping concentration. It was found that radiation trapping exists generally in two glass matrices, even at low doping concentration (⩽0.1 mol% Er2O3). The larger effect of radiation trapping in tellurite glasses compared with phosphate glasses is due to its larger emission cross-section at 1.5 μm band and the spectral overlap between the emission and absorption spectra of Er3+: 4I13/2 ↔ 4I15/2transition. Due to radiation trapping, the measured lifetime of the Er3+: 4I13/2 level in tellurite glasses increases by about 11–37% with increasing the sample thickness at the different erbium doping concentration, while 6–17% for phosphate glasses. And the full-width at half maximum of fluorescence (FWHM) of Er3+: 4I13/2 → 4I15/2 transition in tellurite glasses increased by about 15–64% with increasing the sample thickness, while 11–55% for phosphate glasses. It caused a high overestimation on the figure of merits (FOM) for amplifier bandwidth (σe × FWHM).

Er2O3-doped Bi2O3–B2O3–Ga2O3 glasses were prepared by the conventional melt-quenching method, and the Er3+:4I13/2 → 4I15/2 fluorescence properties are studied for different Er3+ concentrations. when the Er2O3 concentration increases from 0.03 to 3.0 mol%, the measured lifetime of Er3+:4I13/2 level decrease from 2.24 to 0.9 m s, and from 0.25 to 0.20 m s for the Er3+:4I11/2 level. The fast energy migration among Er3+ ions cause the reduction of lifetime of the 4I13/2 level, whereas the change in the 4I11/2 level is mainly due to a cooperative upconversion process (4I11/2, 4I11/2) → (4F7/2, 4I15/2). Based on the dipole–dipole interaction theory, the interaction parameter, CEr,Er, for the migration rate of Er3+:4I13/2 ↔ 4I13/2 was calculated to be 32 × 10−40 cm6 s−1.

•Most ChG fiber media for SC generation usually contain the toxic element arsenic, such as As2S3 and As2Se3 glasses.•Ge–Sb–Se glasses exhibit higher optical nonlinearities, and have more environmentally favorable.•Therefore, we selected Ge–Sb–Se glasses to prepare the MOF fiber.•Finally, SC spanning from ∼3 μm to ∼8 μm was generated.This work experimentally demonstrates the supercontinuum (SC) generation in a three-hole arsenic free Ge20Sb15Se65 chalcogenide suspended-core fiber. Mechanical drilling was used to prepare the chalcogenide glass preform, which was drawn into suspended-core fibers. The zero-dispersion wavelength of the fiber is moved toward the shorter wavelength of about 3.2 μm through changing the fiber core diameter by controlling the pressure of inert gas during fiber drawing. When a 15 cm-long fiber with a core diameter of 6 μm is pumped using 150 fs pulses at 3.3 μm, SC spanning from ∼3 μm to ∼8 μm was generated.

A number of Ge17Ga4Sb10S69−xSex (x = 0, 15, 30, 45, 60, and 69) chalcogenide glasses have been synthesized by a melt-quenching method to investigate the effect of the Se content on thermo-mechanical and optical properties of these glasses. While it was found that the glass transition temperature (Tg) decreases from 261 to 174 °C with increasing Se contents, crystallization temperature (Tc) peak only be observed in glasses with Se content of x = 45. It was evident from the measurements of structural and physical properties that changes of the glass network bring an apparent impact on the glass properties. Also, the substitution of Se for S in Ge–Ga–Sb glasses can significantly improve the thermal stability against crystallization and broaden the infrared transmission region.

•The simulated and experimental results of the output transmission under different waist length and taper ratio.•Ge15Sb20Se65 bare glass fiber with a diameter of 500 μm was fabricated.•The effect of different temperature and tapering speed on the properties of the taper fiber and the energy distribution in the waist region of the taper fiber should be explored.•Experimental setup for the fabrication of chalcogenide fiber taper should be provide.In this work, Ge15Sb20Se65 bare glass fiber with a diameter of 500 μm was fabricated, and then tapered with different tapering parameters. The analysis of Raman and energy dispersive X-ray spectra (EDS) indicated that, a slight change in the chemical composition of the glass, fiber and tapering fiber has negligible effect on the glass structure. It was found that, the waist diameter decreases exponentially with increasing tapering length and speed, and high quality taper fiber with the cone diameter of 2.65 μm can be achieved under the optimal tapering conditions. Finally, the simulated and experimental results of the output transmission under different waist length and taper ratio show that the transmission decreases with increasing waist length and taper ratio.