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By conventional melt‐quenching techniques, a series of Dy3+‐doped (0.1 to 1.0 wt%) Ga5Ge20Sb15S60 bulk glasses were fabricated and their potential for developing mid‐infrared fiber laser beyond 4 μm were evaluated, in which the optimal Dy3+ doping concentration was found to be 0.3 wt% and the largest laser quality factor value (σe × τmea = 2.62 × 10−23 cm2 s) among all of the Dy3+‐doped chalcogenide glass was obtained. On this basis, through using the chemical purification methods with chlorine gas combined with the dynamic distillation process, the high‐purity GGSS glasses with low O–H and S–H absorptions were successfully fabricated, which was confirmed by the optimized mid‐infrared linear transmittance and improved fluorescent lifetimes of Dy3+: 6H13/2, 6H11/2 levels. Furthermore, for the first time to the best of our knowledge, the Dy3+‐doped, single‐mode, and double‐cladding chalcogenide fibers with the core/cladding ratios of 125:60:11 and 125:66:11.5 were achieved by a multistage rod‐in‐tube fiber drawing process and extrusion methods, respectively. The GeS2‐based fiber exhibits excellent transmission performance at 1.0‐5.0 μm: 3.0 dB/m at 2.9 μm (O–H), 2.4 dB/m at 4.1 μm (S–H). Combining the advantages of high‐purity, high doping concentration and single‐mode double‐cladding structure, the optimized active fiber should be an ideal efficient and low‐threshold medium toward mid‐infrared fiber laser beyond 4 μm. [ABSTRACT FROM AUTHOR]

A combined infrared suspended-core fiber (SCF) is fabricated using a stacked glass extrusion method. As2S 3 glass is used as the center core host material, and Ge20As20Se15Te45 glass is used to form supporting bridges and act as the ring host material. In this paper, a continuous and robust extrusion process was used to fabricate the SCFs on stacked chalcogenide glass substrates. Glass flow disruption and shear band formation at the interfaces between the different glasses were avoided while the suspended core was formed directly from the core glass. The near-field optical energy distribution image of the resulting multimaterial SCF shows that light propagates effectively in the core. The losses of the multimaterial SCF were also measured at wavelengths ranging between 2.5 and 7 μm, and the lowest transmission loss was 1.86 dB/m at 4.8 μm. The spectral behavior of the supercontinuum (SC) in the SCF is investigated by varying the pump wavelength and the pump power. A mid-infrared SC spanning a wavelength range from 2.05 to 6.95 μm is generated in a 19-cm-long combined chalcogenide SCF that is pumped at 4.5 μm using an optical parametric amplifier laser system. [ABSTRACT FROM AUTHOR]

In this work, a theoretical study was conducted on temperature sensing in Ge-Sb-Se multimode fibre Bragg grating (MM-FBG). The sensing characteristics of the designed MM-FBGs with different fibre parameters and operating wavelengths were calculated using a coupled model method. The temperature sensitivity of this MM-FBG was found to improve significantly by shifting the operating wavelength from telecom range to mid-infrared (MIR) and utilizing the wide transmission range of Ge-Sb-Se glasses. The temperature sensitivity of the proposed Ge-Sb-Se MM-FBG was calculated to be 0.0758 nm/°C at 1550 nm, which is 7.58 times higher than silica FBGs at 1550 nm, and the temperature sensitivity was calculated to be more than 0.16 nm/°C at 3390 nm, which is 2.2 times higher than that at 1550 nm. In addition, the proposed MM-FBGs provided multi-peak information, and the sensitivity of each peak was calculated to be comparable to the single-mode FBG. The proposed Ge-Sb-Se MM-FBG has great potential for temperature sensing in MIR because of its advantages of simple preparation, high coupling efficiency, multi-peak information and wide working window. [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]

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]

A Co2+:ZnS-doped chalcogenide glass with broadband mid-infrared emission was prepared by using a hot uniaxial pressing process. The refractive index difference (Δn) between matrix glass (As 2 S 5) and crystal (Co2+:ZnS) was controlled to be 0.0042 in the emission spectral range of Co2+ to minimize the scattering effect. An ultrabroadband mid-infrared emission of 2–4 μm was observed at room temperature in the samples after excitation by using a commercially available laser diode of 1550 nm. The significant changes in the lifetime and fluorescence intensity of Co2+:ZnS-doped chalcogenide glass were measured in the temperature range of 90–290 K. A resolution of approximately 0.18 K was observed when used as a temperature detector. Furthermore, a gas-sensing device was built by using the strong and broad emissions of the sample, and the detection sensitivity of butane reached 56 ppm. These results show that this glass-ceramics can be used as optical sensing of gas and temperature. [ABSTRACT FROM AUTHOR]

We report a broadband supercontinuum generation in a chalcogenide fiber taper with an ultra-high numerical aperture. The chalcogenide step-index fiber consisting of As 2 Se 3 core and As 2 S 3 cladding was fabricated by using the isolated stacked extrusion method. The fiber taper with a core diameter of 1.75 μm was prepared by employing a homemade tapering setup. By pumping the fiber taper with a femtosecond laser pulses at 3.3 μm, a broadband supercontinuum generation spanning from 1.9 to 5.7 μm was achieved. [ABSTRACT FROM AUTHOR]

Chalcogenide suspended core fibers are considered as an excellent candidates for several applications in near-and-mid IR applications because of their characteristics of higher linearity and nonlinearity. In this paper, the influence of the fiber structure and host glass on dispersion and nonlinear properties, including the core size and the width of the bridge, especially the shape of the fiber core were analyzed with the finite element method in detail. And then, the optimized structure of SCFs made of As 2 S 3 , Ge 20 Sb 5 Se 75 , As 2 Se 3 , Ge 15 As 15 Se 17 Te 5 , which stand for the typical samples of S-based, Se-based and Te-based chalcogenide glasses, have been adopted to get suitable dispersion properties and highest nonlinear optical properties in all kinds of glasses. [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]