Materials Science and Engineering B 127 (2006) 138–143 Single-mode infrared fibers based on Te As Se glass system V.S. Shiryaev, C. Boussard-Pl´ edel ∗ , P. Houizot, T. Jouan, J.-L. Adam, J. Lucas Laboratoire des Verres et C´ eramiques, UMR CNRS 6512, Institut de Chimie de Rennes, Universit´ e de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France Received 27 May 2004; received in revised form 29 September 2005; accepted 5 October 2005 Abstract Core–clad single-mode optical fibers based on high-purity Te As Se glasses prepared by chemical and physical methods of purification have been drawn. The “build-in casting” and “rod-in-tube” techniques were used to form the high ratio of core/cladding diameters. The minimal optical losses measured by cut-back method were 0.33 dB/m at 7.5 m for Te As Se glass fiber with core diameter of 20 m and cladding diameter of 450 m. The optical losses in the spectral range between 9 and 11 m were equal to 1–3 dB/m. © 2005 Elsevier B.V. All rights reserved. Keywords: Chalcogenide Te As Se glass; Single-mode fiber; Optical losses; Fiber drawing 1. Introduction Single-mode IR fibers transparent in the 3–12 range m and having low optical losses are necessary for creating different opto-electronic devices and systems using IR light transmission [1,2]. Advantages of Te As Se glasses for manufacturing opti- cal fibers are: low phonon energy, good transparency between 2 and 12 m, potentially low optical losses at about 7 m, pos- sibility of modifying the composition to obtain the required optical characteristics, good thermal stability and good chemical durability. The intrinsic multi-phonon absorption of Te As Se glasses is shifted to longer wavelengths in comparison with As 2 Se 3 glass due to the presence of lower frequency vibra- tion modes in Te As Se. When 30% Se is replaced by Te in As 40 Se 60 glass, the multi-phonon absorption edge is shifted by 1.0 m at 0.01 cm -1 absorption level [3]. These glasses are very stable against devitrification and some compositions exhibit no crystallization peak on DSC curves when heated at a rate ranging from 5 to 20 ◦ C/min. For example, the Te x As 40 Se 60-x glasses with x between 10 and 25 show a low tendency to crystallization [4]. In the literature, some data are available on manufacturing single-index [5–7] and multimode core–clad Te As Se fiber [8–10]. A single-index fiber based on Ge 30 As 10 Se 30 Te 30 glass ∗ Corresponding author. Tel.: +33 223236734; fax: +33 223235611. E-mail address: catherine.boussard@univ-rennes1.fr (C. Boussard-Pl´ edel). with optical losses of 0.11 and 1.88dB/m at, respectively, 6.6 and 10.6 m, respectively, has been reported [5]. An unclad fiber from As 40 Se 30 Te 30 glass had optical losses of 3.5 dB/m at 10.6 m [6]. The minimal optical losses were equal to 0.07 dB/m at 7.3 m for As 40 Se 35 Te 25 glass fiber and 0.04 dB/m at 6.7 m for As 30 Se 50 Te 20 glass fiber [7]. Such single-index fibers can be used, for example, as infrared evanescent wave chemical sensors in the biological or environmental domains [8,9]. The preparation of single-index fibers with low optical losses give information on the possibility to obtain low loss core–clad fibers from the studied glasses. Creation of core–cladding glass structure permits the appli- cation of protective coatings, which increases significantly the temporal stability of optical and mechanical parameters of fibers [10]. It is also the first step towards the preparation of single- mode fibers. In multi-mode core–cladding glass fiber the radi- ation propagates only inside the core. In single-mode fiber, 10–30% of radiation power propagates in the cladding, depend- ing on radiation wavelength and core diameter [11]. In paper [12], the preparation of glass fiber with core–cladding struc- ture was reported (core from GeSeTe system and cladding from GeAsSeTe system). These fibers had minimal optical loss of 0.24 dB/m at 7.2 m. According to ref. [13], the core–clad fiber of Ge 2 As 38 Se 40 Te 20 /Ge 2 As 36 Se 44 Te 18 composition manufac- tured by double crucible method has optical losses of 0.15 dB/m at 6.6 m and 3.6 dB/m at 10.6 m. The “rod-in-tube” method [14], and “double crucible” method [13] are generally used to prepare core–clad fibers. In a previous paper [15], we have 0921-5107/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.mseb.2005.10.017