Framework influence of erbium doped oxyfluoride glasses on their optical properties Marcin S ´ roda a,⇑ , Katarzyna Cholewa-Kowalska a , Marek Ró _ zan ´ ski b , Marek Nocun ´ a a AGH – University of Science and Technology, Faculty of Materials Science and Ceramics, al. Mickiewicza 30, 30-059 Kraków, Poland b Institute of Physics, Nicolaus Copernicus University, ul. Grudziadzka 5, 87-100 Torun ´, Poland article info Article history: Received 10 June 2010 Received in revised form 9 September 2010 Accepted 27 September 2010 Available online 27 October 2010 Keywords: UV edge absorption Erbium Oxyfluoride glass Transmittance Refractive index Luminescence abstract Glasses of different matrix (phosphate, borate, silicate and lead-silicate) were studied for their optical properties. The effect of Er dopant on transmittance and luminescence properties was presented. The sig- nificant ‘‘red shift” and ‘‘blue shift” of UV edge absorption were discussed based on the changes in the framework of the borate and phosphate glasses, respectively. It was showed that the integral intensity of the two main optical absorption transitions monotonically increases with the order: phos- phate < borate < silicate < lead-silicate. Ellipsometric measurement was applied to obtain the refractive index of the glasses. The correlation between the shift of edge absorption and the change of refractive index was presented. Effect of glassy matrix on luminescence of Er 3+ was discussed. Ó 2010 Elsevier B.V. All rights reserved. 1. Introduction In the last decade, oxyfluoride transparent glass ceramics doped with lanthanide ions based on the aluminosilicate glassy matrix have been studied [1–3]. The materials have shown to have good combination properties for the development optical devices used as optical amplifiers, up-conversion fibers and solid-state lasers [4]. Due to the best mechanical and chemical properties the oxide glasses based on the silicate framework are the main group of opti- cal materials. Their refractive and dispersion coefficients change in wide range of n d = 1.4–2.1 and m d = 120–30, respectively [5]. The transparency of v-SiO 2 reaches from 160 nm to 4 lm. Modifica- tions of optical properties may be achieve either by the introduc- tion of modifiers (i.e. Li 2 O, K 2 O, BaO, Bi 2 O 3 and PbO) or by change of the main network former (i.e. B 2 O 3 ,P 2 O 5 and PbO) in the cation sub-framework as well as by replacement of anion (i.e. halides, chalcogenides). The phosphate glasses with low dispersion and relatively high refractive indexes were developed in the past. But they are still potential materials for optoelectronics application [6]. The high rare-earth ions concentrations can be maintained for the phosphate glass [7]. Thus, they are potential materials for short optical amplifiers what is a great challenge for integrated optic [8]. Fluoride glasses are interesting materials due to their wide transparency form UV to IR, low optical loss and low phonon energy [9]. The glasses can be easily doped with ions of rare-earth elements (RE) to obtain efficient luminescence [10,11]. Disadvan- tages of the non-oxide glasses are their low mechanical durability, thermal and chemical resistivity [12]. A solution of the problem is transparent oxyfluoride glass–ceramics with low phonon fluoride crystals as a host for RE [13–16]. In the paper, influence of a type of oxide matrix on optical prop- erties of oxyfluoride glass doped Er 3+ ions as a starting-point for achieving transparent glass–ceramic are determined for phos- phate, borate, silicate and lead-silicate glasses. Generally, rear earths (RE) are regarded as a modifier of the glassy framework. Specially, for multi-framework glasses a position of RE in the glassy structure may be different and depends on the interaction of the main components, i.e. chemical affinity. It may lead to the different environment of the RE in the glass and cause particular optical properties. The paper is a confirmation attempt of the above state- ments. The results are in accordance with our study of the same glasses doped with Pr 3+ ion [17]. 2. Experiment 2.1. Glass preparation A series of glasses have been obtained by melting 20 g batch of chemically pure raw materials: SiO 2 , Na 4 P 2 O 7 , (NH 4 ) 2 HPO 4 , BaCO 3 , LaF 3 , Na 2 CO 3 and Er 2 O 3 in a platinum covered crucible at the range 1100–1400 °C(Table 1). The duration of melting was 1 h at the 0925-3467/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.optmat.2010.09.025 ⇑ Corresponding author. E-mail address: msroda@agh.edu.pl (M. S ´ roda). Optical Materials 33 (2011) 397–401 Contents lists available at ScienceDirect Optical Materials journal homepage: www.elsevier.com/locate/optmat