Extrusion of chalcogenide glass preforms and drawing to multimode optical fibers Shaun D. Savage a,b , Cheryl A. Miller a,c , David Furniss a , Angela B. Seddon a,d, * a Novel Photonic Glasses Group, Wolfson Centre for Materials Research, School of Materials, Mechanical and Manufacturing Engineering, Nottingham University, Nottingham NG7 2RD, UK b School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, P.O. Box 88, Manchester M60 1QD, UK c Department of Oral and Maxillofacial Medicine and Surgery, School of Clinical Dentistry, University of Sheffield, Sheffield S10 2TA, UK d The Royal Academy of Engineering / Leverhulme Trust Senior Research Fellow 2007–2008, 3 Carlton House Terrace, London, UK article info Article history: Received 12 October 2007 Received in revised form 21 January 2008 PACS: 42.70.km 42.81.Bm 81.05.Kf Keywords: Fibers and waveguides Infrared fibers Optical fibers Glass transition Infrared glasses Chalcogenides Optical spectroscopy Scanning electron microscopy Defects Absorption FTIR measurements Infrared properties Viscosity and relaxation Viscosity abstract We report on viscosity of a Ge 17 As 18 Se 65 glass over the temperature range of 280–420 °C and the success- ful co-extrusion and fiber-drawing of two chalcogenide glass boules to form a core/clad. pair. The co- extrusion produces a preform with optimum diameter stability and core/clad. glass ratio, and minimum defects at the core/clad. interface in the middle 120–200 mm region of a 270 mm long preform. Core/clad. fiber is drawn successfully from the extruded preform. An optical loss of 1.7 dB m 1 at 1666 cm 1 (6.0 lm) and 6.7 dB m 1 at 6649 cm 1 (1.55 lm) is reported. Ó 2008 Elsevier B.V. All rights reserved. 1. Introduction Chalcogenide glasses have been studied in depth for about 40 years due to their wide transmission window, encompassing the mid-visible to far-infrared (0.5–20 lm), depending on glass com- position [1,2]. They are of current interest due to their potential applications in such areas as remote-chemical and biological spec- troscopic sensing, laser power delivery, displacement sensors, Bragg gratings, switching devices and infrared imaging systems [3–8]. To achieve any of these applications, it is desirable that chalco- genide glasses be produced in a useful waveguide form, such as core/clad. optical fiber. Core/clad. fiber may be drawn directly from the melt above the liquidus using a double crucible arrangement to contain the core and cladding glass melts. Notwithstanding that the chalcogenides tend to have high vapor pressures at these ele- vated temperatures, success in double crucible fiber-drawing has been achieved for instance by applying a local inert gas pressure to the double crucible [7,9]. Core/clad. chalcogenide glass optical fiber may also be pulled from a glass preform. The current methods of chalcogenide glass preform production have major drawbacks. One route involves intricate silica glass containment that must be swivelled in very specific patterns to achieve a core/clad. chalcogenide glass rod preform [10]. Others have utilized rod-in-tube techniques. For 0022-3093/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jnoncrysol.2008.01.032 * Corresponding author. Address: Novel Photonic Glasses Group, Wolfson Centre for Materials Research, School of Materials, Mechanical and Manufacturing Engi- neering, Nottingham University, Nottingham NG7 2RD, UK. Tel.: +44 (0) 115 8466755; fax: +44 (0) 115 951 3800. E-mail address: angela.seddon@nottingham.ac.uk (A.B. Seddon). Journal of Non-Crystalline Solids 354 (2008) 3418–3427 Contents lists available at ScienceDirect Journal of Non-Crystalline Solids journal homepage: www.elsevier.com/locate/jnoncrysol