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• Two kinds of fibers based on S-rich and S-poor have been fabricated successfully. • As-S-Se system has a transmission varied range between full S-based and full Se-based. • S-rich fiber shows a lower loss, the of S-poor fiber shows a better SC results. Two kinds of single-mode (SMF) step-index(SIF) chalcogenide fibers based on S-rich and S-poor As-S-Se glass have been fabricated successfully by an isolated extrusion method. We experimentally explored the effects of S and Se weights on the IR light transmission in the infrared area of the waveguide medium. By exploring the infrared transmission. It is found that the As-S-Se system has a transmission varied range between full S-based (As 2 S 3) and full Se-based (As 2 Se 3) glasses. The results show that with the addition of selenium, the red-shift is observed in both the short-wavelength absorption edge and long-wave cut-off wavelength. This phenomenon can be sourced from the varying of optical band gaps and phonon energies. Simultaneously, single-mode fibers was employed to evaluate the attenuation and supercontinuum(SC). We found that S-rich fiber shows a lower optical loss of 0.67–1.5 dB/m in 4.1–5.9 μm region, with a minimum value of 0.67 dB/m at 4.6 μm than that of S-poor fiber does. Yet, the SC results of S-poor fiber shows a flatter and broader spectrum region than that of S-rich fiber does. [ABSTRACT FROM AUTHOR]

Abstract: The Ce3+ ion was introduced into Er3+ doped TeO2–GeO2–Nb2O5–Li2O (TGNL) glass to improve the 1.5μm fluorescence characteristics. As increasing of Ce3+ concentration, the lifetime of Er3+:4I11/2 level is shortened form 360 to 225μs, while the Er3+:4I13/2 level remains unchanged. Accordingly, the upconversion fluorescence (blue, green and red) was quenched. Improved 1.5μm emission is obtained and the reason is ascribed to the increase of nonradiative rate between the 4I11/2 and 4I13/2 level of the Er3+ ions. [Copyright &y& Elsevier]

Abstract: 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 3.0mol%, the measured lifetime of Er3+:4I13/2 level decrease from 2.24 to 0.9ms, and from 0.25 to 0.20ms 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, C Er,Er, for the migration rate of Er3+:4I13/2 ↔ 4I13/2 was calculated to be 32×10−40 cm6 s−1. [Copyright &y& Elsevier]

Abstract: The B2O3 was introduced into the Er3+ doped TeO2–ZnO–Na2O glass to increase the phonon energy of the host. The effect of B2O3 on the non-radiative rate of the 4I11/2 → 4I13/2 transition of Er3+, the lifetime of the 4I11/2 and 4I13/2 levels, the green and red upconversion emissions intensity, and the 4I13/2 → 4I15/2 emission intensity was discussed. The results show that the phonon energy of boro-tellurite glass is close to that of germanate glass and is quite smaller than that of borate glass. The lifetime of 4I11/2 level and the upconversion emissions decrease with increasing B2O3 concentration. The higher OH group concentration presented in the boro-tellurite glass may shorten the lifetime of 4I13/2 level and also reduce the quantum efficiency of 4I13/2 → 4I15/2 emission. The future dehydrating procedures are suggested to enhance the efficiency of amplification at 1.5μm band. [Copyright &y& Elsevier]

Abstract: Er2O3-doped Bi2O3–B2O3–SiO2 glasses were prepared by the conventional melt-quenching method, and the Er3+ :4I13/2 → 4I15/2 fluorescence properties have been studied for the different Er3+ concentrations. Infrared spectra were measured in order to estimate the content of OH− groups in samples. The constant , which represents the strength of interaction between Er3+ ions and OH− groups in the energy migration, was calculated to be for Er3+-doped bismuth boro silicate glasses. Based on the electric dipole–dipole interaction theory, the interaction parameter, , for the migration rate of Er3+ :4I13/2 → 4I13/2 in Er3+:Bi2O3–B2O3–SiO2 glasses was about [Copyright &y& Elsevier]

Abstract: Spectroscopic properties of Er3+-doped TeO2–WO3–Bi2O3 (TWB) glass has been investigated. The transition probabilities, excited state lifetimes, and the branching ratios have been predicted for Er3+ based on the Judd–Ofelt theory. The lifetime of 4I11/2 and 4I13/2 level were measured from time-resolved fluorescence decay. The mutiphonon relaxation of 4I11/2→4I13/2 transition in TWB glass was predicted and compared with other glass hosts. Efficient green and weak red upconversion luminescence from Er3+ centers in the glass sample was observed at room temperature, and the upconversion excitation processes have been analyzed. [Copyright &y& Elsevier]

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]

• The high content (6.0 mol%) Er3+ ions doped ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF (ZBLAN) fluoride glass sample with low OH- concentration (0.013 cm−1) was prepared. • The radiative trapping effect of Er3+ ions with different sample size has been investigated. • The numerical modeling results showed the mid-infrared output-laser improved greatly and even exceeded the Stokes limit. The influence of radiation trapping effect on the fluorescence and decay of the heavy concentration Er3+ doped ZBALN glass were investigated, and numerical simulation proves that high-slope efficiency 2.7 µm laser output can be achieved. ga1 The ZBLAN glass with high content of Er3+ was prepared and studied. The glass has a wide infrared transmittance range of 2.5–8.0 µm, which means a lower maximum phonon energy. By testing and analyzing the fluorescence spectrum and lifetime curves under different penetration depths, the intrinsic emission spectrum and lifetime of the sample are obtained without the influence of sub-absorption. Under 980 nm excitation, the maximum emission cross section and the lifetime of 2.7 µm are 6.10 × 10−21 cm2 and 6.49 ms, indicating that high-concentration doping has a larger laser quality factor. According to the rate equation and transmission equation, cascaded and non-cascaded fiber laser models are established to conduct research on 2.7 µm fiber lasers. The slope efficiency can reach 40.38% at a pump wavelength of 980 nm and a fiber background loss of 0.1 dB/m. The high emission cross section, long fluorescence lifetime and high slope efficiency output make ZBLAN glass heavily doped with Er3+ an ideal host material for mid-infrared lasers. [ABSTRACT FROM AUTHOR]

• Arsenic-free low-loss fiber was fabricated by a process of peeled-off extrusion. • The fiber exhibits a minimum optical loss of 0.87 dB/m at 5.1 μm. • The broadest spectrum from 1.56 to 7.59 μm at −30 dB was achieved successfully. A low-loss and Arsenic-free sulfur-based chalcogenide fiber(Ge-Sb-S) was fabricated by a novel process of peeled-off extrusion. The fiber has an optical loss of <2 dB/m in a range from 5 to 6 μm with a minimum loss of 0.87 dB/m at 5.1 μm. A mid-infrared (MIR) supercontinuum (SC) spectrum covering 1.56–7.59 μm was generated from a 22-cm long fiber pumped with a femtosecond laser at 4 μm (−150 fs, 1 kHz). Simultaneously, we demonstrated that the optical fiber has a transmission efficiency of 53% at 4 μm, which is the key significance for applications such as IR night vision, bio-photonics, military defense and environmentally friendly industry. [ABSTRACT FROM AUTHOR]

In order to improve the thermal stability of chalcohalide glasses, which is beneficial for fiber drawing, and blue-shifting zero-dispersion-wavelength (ZDW), which is beneficial to generate supercontinuum (SC) spectra, so more germanium (Ge) is needed to be incorporated into the glass network of Ge-As-Se-I. Here, two series of (Ge 20 As x Se 80- x) 85 I 15 and (Ge x As 40- x Se 60) 85 I 15 glasses are investigated on the optical properties, including absorption edge at short wavelength, optical band gap, linear refractive index and ZDW. The glass transition temperature (Tg) and the soften temperature (Tp) of these glasses are also investigated. In general, as the ratio of Ge/As changes, optical properties of (Ge x As 40- x Se 60) 85 I 15 glasses change regularly, but when the ratio of As/Se changes, those of the (Ge 20 As x Se 80- x) 85 I 15 glasses keep weak regularity relatively. Generally, the effect of Ge on Ge-As-Se-I glasses' properties is well presented in this work, and this will show much help to develop novel mid-infrared fiber and device in the future. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (NPs) were introduced into the Er3+-doped tellurite glasses (TeO2–Bi2O3–TiO2) and their effects on the 1.53µm band fluorescence of Er3+ and thermal stability of glass host were investigated. It was found that the presence of silver NPs nucleated and grown during the heat annealing process, could improve the thermal stability and the 1.53µm band fluorescence. Maximum enhancement in the 1.53µm band fluorescence was obtained in sample heat-treated for 48h. However, further increase in the heat annealing time (~72h) reduces the fluorescence intensity. Enhancement in the 1.53µm band fluorescence is attributed to the increased local electric field induced by silver NPs whereas the quenching is ascribed to the energy transfer from Er3+ ions to silver NPs. [ABSTRACT FROM AUTHOR]

Chalcogenide glass fiber usually possesses a single zero-dispersion wavelength (ZDW) that is more than 5 µm. Here, a novel W-typed double cladding chalcogenide glass fiber was designed and fabricated with optimized dispersion properties based on As 2 Se 3 -Ge 7 As 23 S 70 -Ge 10 As 23 Se 67 glasses. The results show that there are two ZDWs locating at near-infrared 2.95 µm and far-infrared 11.77 µm, and the dispersion less than 8 ps/km/nm at this range. Based on numerical simulation and viscosity analysis, a novel W-typed double-cladding fiber is fabricated via extrusion method, and the lowest loss of 1.15 dB/m is obtained at 5.68 µm. The optimized structure and dispersion distribution of the fiber ensure the excellent supercontinuum generation. When pumping at 3 µm near the first ZDW, a bandwidth supercontinuum (SC) spanning from 1 to 10.9 µm can be obtained. By pumping at 5 µm, a broad bandwidth of SC output from 1.3 to 13 µm can be obtained. This kind of low ZDW fiber has great potential for the generation of supercontinuum in the future. [ABSTRACT FROM AUTHOR]

Abstract: Heat-treatment was used to precipitate PbS quantum dots (QDs) in silicate glasses doped with different amounts of Ag2O, and the influence of Ag2O on QDs was investigated. Under given heat-treatment conditions, the absorption coefficients and photoluminescence intensities of PbS QDs increased with the addition of Ag2O. Ag clusters formed by thermal treatment nucleated formation of PbS QDs in glasses. [Copyright &y& Elsevier]

It is well known that, the incorporation of halide will improve the optical properties of chalcogenide glasses with a broad transparent range. Here, we investigated the optical properties and structure of Ge-As-Se-I glasses in order to disclose the role of halogen iodine in the formation of chalcogenide glassy network. It was found that, refractive index, zero dispersion wavelength and glass transition temperature Tg decrease with increasing iodine contents, while the cut-off edge (λ vis) in the shorter wavelength blue-shifts apparently, and the whole transmission range is expanded widely. The glasses show good chemical stability against moisture. The zero dispersion wavelength of the glasses can be decreased to 4.32 μm by iodine-doping. The evolution of Raman spectra of the glasses indicates that, there is no obvious peak of iodine in Ge-As-Se-I glasses and the dominated glassy network are still the (Ge Se) heteropolar bonds. Unlabelled Image • These novel glass samples possess wide IR transparent window of 0.75-18 μm. • The ZWD of the glass can be decreased to 4.32μm while the refractive index is as low as 2.162 @1.7μm. • The strong absorption peaks of Ge O bond(12.5μm) and H 2 O(6.31μm) are all eliminated after effective purification. [ABSTRACT FROM AUTHOR]

• A dual-clad step-index chalcogenide fiber based on tellurium glasses was proposed and investigated detailedly for midinfrared coherent supercontinuum generation. • The structure of the fiber with a W-type refractive-index profile was numerically studied and optimized for all-normal dispersion profile. • Due to the large material zero dispersion wavelength, an all-normal dispersion tellurium chalcogenide fiber was realized via the waveguide chromatic engineering. • The optimized fiber was fabricated via extrusion and employed for coherent supercontinuum generation. • The result shows that a high coherent supercontinuum covering 3.5–10.5 μm can be generated in this fiber with 5 μm femtosecond laser pumping. • This is the first numerical investigation on the dispersion engineering of tellurium chalcogenide dual-clad step-index fiber. Considerable investigations have been carried out for chromatic dispersion tailoring of chalcogenide glass fiber with various structures and different material compositions. Here we proposed a tellurium-based chalcogenide glass fiber with a dual-clad structure in a W-type refractive-index profile. The structure of the fiber based on Ge-As-Se-Te glasses was numerically analyzed in detail. The simulation results indicate that an all normal dispersion profile can be realized in this tellurium glass fiber with an optimized dual-cladding structure. Then the optimized tellurium chalcogenide fiber with an all-normal dispersion profile was fabricated by multi-extrusion method. Pumping with a 5 μm ultra-short pulsed laser (150 fs, 1 kHz), abroadband supercontinuum (SC) covering 1.5–11 μm can be generated in the 19 cm-long fiber. The coherence of SC was also investigated by numerical simulation. The result shows that a high coherent SC covering 3.5–10.5 μm can be generated in this all-normal dispersion fiber. In conclusion, all-normal dispersion profile can be realized easily in this tellurium-based glass fiber due to their large materials ZDWs. [ABSTRACT FROM AUTHOR]

A chemically stoichiometric chalcogenide (ChG) glass fiber with ultra-high germanium-containing has been realized for the first time. Here, an isolated extrusion (ISE) with a peeled-off method was carried out for the fiber fabrication with glasses of core Ge 33 As 12.5 Se 54.5 and cladding Ge 33 As 12 Se 55. The fiber exhibits an optical loss of < 3 dB/m in a range of 5.1–7.9 μm, and the minimum loss of 2.11 dB/m was obtained at 6.61 μm. For SC generation, The broadest spectrum from 1.66 to 11.40 μm at − 30 dB was achieved in the 13 cm-long fiber pumped by 5 μm laser with pump power of 25 mW. This fiber possesses the potential applications of high power laser generation and transmission. [ABSTRACT FROM AUTHOR]

• Morphologies of damage craters were inequable with an increasing laser fluence. • Damage threshold on surface of As 2 S 3 fiber is slightly larger that of As 2 S 3 glass. • Morphologies of damage craters on surface of As 2 S 3 fiber and glass were similar. • Compared with damage in MIR region, damage threshold decreased under 800 nm laser. In this study, we investigated femtosecond laser-induced damage on the end face of an As 2 S 3 chalcogenide (ChG) glass fiber by repeatedly inducing 1 kHz ultrashort pulses with 150 fs duration at 800 nm wavelength in comparison with the bulk As 2 S 3 glass. The damage size, geometries, and morphology changes under different laser powers were measured and analyzed with optical, and scanning electron microscopes (SEM). The laser-induced damage threshold on the end face of three As 2 S 3 fibers calculated using the linear regression method was 32.15 mJ/cm2, whereas that of As 2 S 3 bulk glass was approximately 24.32 mJ/cm2. The femtosecond laser-induced damage on the As 2 S 3 bulk glass at 800 nm wavelength was also compared with that in the mid-infrared (MIR) region, which indicates a decrease in the damage threshold and an aggravation in the morphologies of damage craters under an irradiation of 800 nm femtosecond pulsed laser. To the best of our knowledge, this study is the first to investigate the interaction of femtosecond laser with the end face of ChG glass fiber. This work provides scientific guidance for the fabrication of novel photonic devices based on ChG glass fibers. [ABSTRACT FROM AUTHOR]

This study reports on the synthesis of tellurium-based chalcogenide films that have high thermal stability for phase change memory application. Several Te-based chalcogenide alloys of In-Bi-Te, Ag-Bi-Te, In-Sb-Te, Sn-Sb-Te, Zn-Ge-Te, and Ga-Ge-Te are reported. Their thermal, optical, and electrical properties are investigated. The results show that Bi-Te-based films have a higher crystallization temperature and greater activation energy compared with the other Sb-Te-based and Ge-Te-based films. Especially, In2.8Bi36.6Te60.6 film exhibits high crystallization temperature (252 °C) and great activation energy (5.16 eV), showing much improved amorphous thermal stability. A relatively wider optical band gap (0.674 eV) of thermal annealed In2.8Bi36.6Te60.6 film is obtained. In addition, it also has a higher amorphous/crystalline resistance ratio of about 105, implying that current consumption could be low in the phase-change memory operation. [ABSTRACT FROM AUTHOR]

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]