M.V. Sukhanov

Infrared luminescence in Bi-doped Ge–S and As–Ge–S chalcogenide glasses and fibers

Experimental and theoretical studies of spectral properties of chalcogenide Ge–S and As–Ge–S glasses and fibers are performed. A broad infrared (IR) luminescence band which covers the 1.2 – 2.3 μm range with a lifetime about 6 μs is discovered. Similar luminescence is also present in optical fibers drawn from these glasses. Arsenic addition to Ge–S glass significantly enhances both its resistance to crystallization and the intensity of the luminescence. Computer modeling of Bi-related centers shows that interstitial Bi+ ions adjacent to negatively charged S vacancies are most likely responsible for the IR luminescence.

Multimode Chalcogenide Fibers for Evanescent Wave Sensing in the Mid-IR

Evanescent wave spectroscopy in the mid-infrared (MIR) is a powerful tool for remote real-time sensing. Chalcogenide fibers transparent in MIR are considered as a base for creation of a fiber-optical platform for the MIR sensing. In this paper, a rigorous theoretical approach has been applied for the analysis of evanescent modes propagation in a multimode chalcogenide fiber surrounded by an absorbing medium. A role of particular evanescent mode in power delivering through the fiber has been revealed. Strong absorption of water in this spectral range has been shown to be a main factor limiting sensitivity of the evanescent wave sensor. Possibilities of sensitivity enhancement by using waveguiding properties of the fiber have been discussed. The analysis is supported with an experimental measurement of a [GeSe4]95I5 glass fiber partially immersed in an aqueous acetone solution, in the wavelength range of 2-5 μm.

Fine purification of monoisotopic 32S and 34S

We have proposed and tested a combined process for ultrapurification of monoisotopic 32S and 34S sulfur, which comprises thermochemical treatment of sulfur vapor on silica and ceria packing, melting with aluminum, and distillation. The impurity composition of the purified sulfur has been determined by atomic emission and IR spectroscopy. We have obtained monoisotopic 32S and 34S sulfur samples comparable in chemical purity to high-purity sulfur of natural isotopic composition.

Preparation of ZnGa2S4 by reacting GaI3 and ZnI2 with sulfur

We have carried out thermodynamic modeling of the GaI3–S and ZnI2–S systems by the method of equilibrium constants and calculated the chemical compositions of the condensed and vapor phases in the temperature range 200–500°C. Our experimental data demonstrate the feasibility of preparing zinc thiogallate by reacting gallium(III) iodide and zinc(II) iodide with sulfur. Synthesis was carried out at a temperature of 450°C over a period 2 h, followed by calcination of the product at 650°C in order to remove the residual iodine. The practical ZnGa2S4 yield was 92–94%.

Chalcogenide sensing elements for the mid-IR analysis of liquids: design on the base of electromagnetic theory of optical fibers

Fiber-based evanescent wave spectroscopy in the mid-IR is a powerful tool for the remote chemical analysis of liquids and gases in real time. Design of a sensing element of the fiber sensor is important for optimization of its output characteristics. In addition to unclad chalcogenide fibers that were previously used as the sensing elements, we consider core-clad fibers consisting of a multimode core and a ring cladding with the refractive index greater than that one of the core. For numerical analysis, a theoretical approach based on electromagnetic theory of optical fibers has been used. Calculated transmittance of the sensing elements is compared with the measured output characteristics of a sensing element made of an unclad chalcogenide fiber, which was immersed into aqueous acetone solutions.