Aluminum co-doping of soda-lime silicate glasses: Effect on optical and spectroscopic properties S. Berneschi a,b, * , M. Bettinelli c , M. Brenci a , G. Nunzi Conti a , S. Pelli a , S. Sebastiani a , C. Siligardi d , A. Speghini c , G.C. Righini a a Optoelectronics and Photonics Department, Nello Carrara Institute of Applied Physics, IFAC – CNR, Via Panciatichi 64, I-50127 Firenze, Italy b Dipartimento di Elettronica Informatica e Sistemistica (DEIS), Bologna University, Viale Risorgimento 2, 40100 Bologna, Italy c Scientific and Technological Department, Verona University, Strada le Grazie 15, 37134 Verona, Italy d Dipartimento Ingegneria dei Materiali e dellÕAmbiente (DIMA), Modena and Reggio Emilia University, Via Vignolese 905, 41100 Modena, Italy Available online 31 May 2005 Abstract One of the limits of using silicate glasses as a host for Er 3+ is the emission bandwidth, which is smaller than in the case of other oxide glasses, such as phosphates and tellurites. The bandwidth can be increased by adding aluminum to the composition. Here we present an experimental investigation of the effect of increasing aluminum content on optical and spectroscopic properties of this glass. Glass samples were prepared by melting at 1550 °C reagent grade SiO 2 , Al 2 O 3 , Na 2 CO 3 ,K 2 CO 3 , CaCO 3 , (NH 4 ) 3 PO 4 and Er 2 O 3 ; Al 2 O 3 concentration ranged from 0.99 to 20 mol%. Both heating and cooling rates were equal to 0.17 °Cs 1 . Measurements of the fluorescence bandwidth were then made and as a function of alumina content. Judd–Ofelt analysis was performed and cal- culated radiative lifetimes were compared with experimental ones. Planar waveguides were also fabricated by using ion-exchange technology, and some optical properties measured by the prism coupling technique. These waveguides had losses of the order of 1 dB/cm at 635 nm. Ó 2005 Elsevier B.V. All rights reserved. PACS: 42.70.Ce; 42.82.Gw; 78.55 Hx; 82.65.Fr 1. Introduction To obtain integrated optical amplifiers based on Er 3+ -doped glass (EDWAs) with performance higher than current devices the optimization of the active mate- rial and the choice of the fabrication process are crucial points. As to the first issue, we consider silicate glasses because of their chemical durability and adaptability to different waveguide fabrication processes [1]. Even if quite good results have already been demonstrated in active integrated optic (IO) devices fabricated in this type of glass [2,3], its application interest may be limited by its larger upconversion coefficient and narrower fluo- rescence bandwidth compared to other oxide glasses such as phosphates and tellurites [4,5]. We already reported on the optical gain achieved in an erbium-doped soda-lime silicate glass, which we developed [3]. We had measured the fluorescence band- width in a set of samples doped with different Er 3+ /Yb 3+ concentrations, and the results indicated a bandwidth of about 17 nm full width half maximum (FWHM) [1,6], which is not very convenient for amplifiers to be used in wavelength-division-multiplexing (WDM) systems. On the other hand, it is known [7–9] that one of the ways to increase the emission bandwidth in a silicate glass is to introduce aluminum. A few papers also discussed 0022-3093/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jnoncrysol.2005.04.008 * Corresponding author. Address: Optoelectronics and Photonics Department, Nello Carrara Institute of Applied Physics, IFAC – CNR, Via Panciatichi 64, I-50127 Firenze, Italy. Tel.: +39 055 423 5243; fax: +39 055 423 5352. E-mail address: [email protected] (S. Berneschi). www.elsevier.com/locate/jnoncrysol Journal of Non-Crystalline Solids 351 (2005) 1747–1753
Aluminum co-doping of soda-lime silicate glasses: Effect on optical and spectroscopic properties
Jun 20, 2023
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