Advanced Optical Glasses for Novel Optical FibersKathleen Richardson, Clemenson University Research Goundation, DMR 0807016

The international, multidisciplinary team is approaching the formation of micro-structured infrared fibers from several perspectives blending experimental and computational expertise. Clemson’s Glass Science group has been quantifying the visco-thermal behavior and interaction between chalcogenide glasses and the hot-forming (substrate) materials used in extrusion and fiber drawing. Clemson’s Mechanical Engineering group is conducting Finite Element Analysis (FEA) simulations to understand the impact of turbulence in the viscous flow of glasses during extrusion. Partners at University of Adelaide have conducted extrusion tests to provide experimental verification of the extrusion results obtained through simulation. Findings show complex flow patterns and thermal non-uniformities in the extrusion furnace and dies, and glass-chemistry specific wetting variations limit the quality of the resulting post-formed structures. Improvements at quantifying temperature profiles and glass-substrate pair optimization will further efforts to improve post-extruded part quality.

(a) Wetting droplets of chalcogenide glass at elevated temperatures on common hot-forming substrate materials (b) The surface profile of a steel substrate showing residual adhered glass (c) Backscattered SEM image of the steel substrate indicating preferential chemical interaction of chalcogenide glass with substrate.

700 μm

The overarching goal of this funded effort is to advance the fundamental understanding of the intrinsic limits of advanced optical glasses for use in traditional and novel fiber geometries. Such an advance in this research area will answer critical materials science questions, extending current capabilities to design, process and manufacture advanced glasses into glass fibers, resolve key questions on glass’ intrinsic physical properties and how they can be tailored, enhanced and optimized to allow use in novel fiber structures.

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(b) (c)

(a) Coupled Eulerian Lagrangian (CEL) extrusion simulation results of a die with a channel containing six holes. (b) The initial stages of extrusion of a solid preform using the Arbitrary Lagrangian-Eulerian (ALE) finite element formulation.. Die swell is evident.

(a) (b)

Advanced Optical Glasses for Novel Optical FibersKathleen Richardson, Clemenson University Research Goundation, DMR 0807016

MWN collaborator exchange: As part of the current collaboration a researcher from the University of Adelaide, Dr. Yinlan Ruan, spent two weeks at Clemson University’s Glass Processing and Characterization Laboratory (GPCL) performing research on chalcogenide glasses. Her primary focus in the Clemson University lab was to better understand the wetting behavior of chalcogenide glasses (prepared at Clemson University) with substrate materials used in optical fiber fabrication (drawn at the University of Adelaide). As part of her visit, she spent time with the graduate and undergraduate students in the PI’s (Richardson) group, on their projects.

University of Adelaide researcher Dr. Yinlan Ruan (right) working with Clemson graduate student Guillaume Guery (left) on the preparation of

a new chalcogenide glass composition.

Dual MS degree program: Guillaume Guery completed his MS in Materials Science and Engineering (Clemson) and Chemistry (Univ. Bordeaux) in August 2010, as part of Clemson’s US Department of Education-funded ATLANTIS-MILMI program. The program, in partnership between MWN partners Clemson–UCF–University of Bordeaux (FRANCE) offers dual MS degrees in Chemistry-Materials Science and Engineering and Physic-Optics to US and INTL participants. Guillaume will continue for his PhD as part of the Clemson-Bordeaux Dual Doctoral program starting Fall 2010 and will complete his degree with our Bordeaux partners on tellurite glass fibers (NSF-MWN funded).