Barry B. Harbison

Spectroscopy of the IR transitions in Pr 3+ doped heavy metal selenide glasses

The spectral properties of Pr 3+ doped BaInGaGeSe chalcogenide glasses are reported. Absorption spectra, emission spectra, and lifetimes of the lower lying manifolds have been measured. Radiative transition rates are calculated and compared with measured experimental lifetimes. The strong mid-IR emission and spectral properties of this glass make this glass a strong candidate for lasers, amplifiers, and high brightness sources in the mid-IR.

BaOGa2O3GeO2 glasses with enhanced properties

Abstract Varying substitutions of In2O3 for Ga2O3 in the BaOGa2O3GeO2 glasses were made and their effects on the glass transition temperature, density, hardness, chemical durability and the infrared transmission were studied. In2O3 substitution for Ga2O3, in general, resulted in improvement in the physical properties of these glasses. The glass transition temperature, density and hardness increased with the substitution. The chemical durability of these glasses improved with the substitutions and the infrared (IR) cut-off edge shifted to longer wavelengths. Phase separation was observed in compositions with higher In2O3 substitutions. The observed changes in physical properties and phase separation with In2O3 substitutions are explained on the basis of a structural model suggesting that octahedrally coordinated In3+ replaces tetrahedrally coordinated Ga3+ in the glass structure. The observed results are in good agreement with the model which also explains the phase separation observed at higher In2O3 substitutions.

Preparation and properties of BaS–Ga2S3–GeS2 glasses

Abstract A new class of sulfide glasses based upon the BaS–Ga 2 S 3 –GeS 2 system has been investigated. Glass compositions were prepared in graphite or vitreous carbon crucibles, encapsulated in silica ampoules, and cooled from a melt temperature of 1000°C. These glasses have good glass stability, with T x − T g in the range of 100 to 200°C, glass transition temperatures between 400 and 500°C, and infrared transmission to wavelengths of about 12 μm. Thermal, optical and mechanical properties of these glasses are reported and the effects of materials purity and processing on these properties are discussed. Their thermal stability and optical transmission band make these glasses candidate materials for rare earth doped lasers and fiber amplifiers, infrared fiber sensors and optical components for infrared systems.

Optical properties of BaO-Ga2O3-GeO2 glasses for fiber and bulk optical applications

Barium gallogermanate glasses are a relatively new family of glasses with tremendous potential for both fiber and bulk optical applications. This ternary system has a broad region of glass forming ability, excellent stability with respect to crystallization, and transmission beyond 5 micrometers . This paper reports the effects of composition and processing on properties critical to both fiber and bulk optical applications of these glasses.

Challenges in obtaining low loss fluoride glass fibers

Abstract The contribution from the different mechanisms to the total loss at 2.55 μ m is reviewed. The observations suggest that extrinsic scattering induced by the different fiberizing techniques is the biggest limitation to achieving low loss in fluoride fibers. Extrinsic scattering is mainly due to microcrystals which grow on heterogeneities which can be subsequently eliminated and bubbles which are frequently present in all fiberizing techniques. A new fiberizing technique called the core injection technique (CIT) is discussed which potentially eliminates the presence of bubbles.

Hermetic Coatings on Fluoride Glass Fibers Using Cylindrical Magnetron Reactive Sputtering

The hollow cathode cylindrical magnetron is demonstrated to be capable of depositing uniform coatings on heavy metal fluoride fibers while maintaining the fiber temperature below 150°C. Pure metal coatings were deposited at typically 3000 A/min, while oxynitride coatings were deposited at roughly 300 A/min. We also demonstrated the hermeticity of AlN coatings for periods of several hundred hours even when immersed in water.

Rare earth doped glass fibers as infrared sources for IRSS

We report on the characteristics of rare earth doped chalcogenide glasses and their applicability as sources for IR scene simulation (IRSS). The characteristics of Pr3+- doped chalcogenide glass fiber sources and arrays operating in the MWIR region between 3 - 5 micrometer are reported. Rare earth doped chalcogenide glasses for LWIR sources are also discussed.

Hot isostatic pressing of fluoride glasses

Abstract Hot isostatic pressing (HIP) has been used in numerous material systems for the elimination of micro-porosity. This process has been developed for the removal of bubbles which result when casting fluoride glasses. Optimization of HIP parameters of times, temperatures, and pressures has been achieved without inducing crystallization or altering the geometry of the fluoride glass casting. Improvements in fluoride fiber strength and lower losses can result from HIP fluoride glass preforms prior to fiber drawing.

Rare-earth-doped chalcogenide glasses for use in mid-IR sources

A bright, broad-band, optically-pumped fiber fluorescent source is described. Fluorescence data obtained from fiber and bulk samples of rare-earth doped chalcogenide glass are presented.

Long-wavelength infrared transmitting glasses: new ternary sulfide compositions

Compositions in the MS-In2S3 and MS-Y2S3 systems (M equals Ca or Sr) have been investigated as potential long-wavelength infrared transmitting materials with possible glass-formability. Previous studies of CaY2S4 and SrY2S4 single crystals show that these phases have intrinsic infrared cut-offs at longer wavelengths than ZnS, however phases in these systems often exhibit poor crystallinity. Preliminary results indicate that these materials are significantly harder than ZnS, however, they are extremely refractory and therefore difficult to melt by traditional methods.