Journal of Physics and Chemistry of Solids 69 (2008) 55–59 Production of defects in ZBLAN, ZBLAN:Tm 3+ and ZBLAN:Cr 3+ glasses by ultra-short pulses laser interaction Lilia C. Courrol a,Ã , Younes Messaddeq b , Sandra H. Messaddeq c , Sidney J.L. Ribeiro b , Ricardo E. Samad d , Anderson Z. de Freitas d , Nilson D. Vieira Jr. d a Departamento de Cieˆncias Exatas e da Terra/UNIFESP, R. Prof. Artur Riedel, 275740, Diadema, 09972-270 SP, Brazil b Instituto de Quı´mica, UNESP-Araraquara, Brazil c Instituto de Fı´sica de Sa˜o Carlos, Sa˜o Carlos, Brazil d Centro de Lasers e Aplicac - o˜es, IPEN/CNEN-SP, Brazil Received 30 October 2006; received in revised form 18 July 2007; accepted 23 July 2007 Abstract In this work we have studied pure and thulium- and chromium-doped ZBLAN glasses irradiated by ultra-short laser pulses. A Ti:sapphire CPA system was used, producing a 500 Hz train of pulses, centered at 830 nm, with 375 mJ of energy and 50 fs of duration (FWHM). The beam was focused by a 20 mm lens, producing a converging beam with a waist of 12 mm. The absorption spectra before and after laser irradiation were obtained showing production of color centers in pure, thulium-doped and chromium-doped ZBLAN glasses. A damage threshold of 9.56 T W/cm 2 was determined for ZBLAN. r 2007 Elsevier Ltd. All rights reserved. PACS: 42.55f; 45.79e; 42.70a Keywords: A. Glasses; D. Colour centres; D. Optical properties; D. Radiation damage 1. Introduction The interaction of femtosecond (fs) laser pulses with matter results in many non-linear processes such as multiphoton absorption, plasma formation, color center (CC) generation and so on. In recent years, the use of infrared fs lasers to induce changes in refractive index in transparent materials has been widely investigated [1,2]. These changes can be used to generate three-dimensional integrated photonic structures in a variety of glasses, and this technique has been applied to fabricate photonic structures, such as passive optical waveguides, gratings and couplers [3]. It is known that the fluoride glasses like ZBLAN (ZrF 4 –BaF 2 –LaF 3 –AlF 3 –NaF) exhibit several interesting properties that can be exploited for the fabrication of photonic devices [4] in particular their excellent infrared transparency (from near UV to far IR) and a very low theoretical attenuation around 2.7 mm are suitable for creating photonic devices. The present investigation is intended to have a compre- hensive understanding of the influence of chromium (Cr 3+ ) and thulium (Tm 3+ ) ions on the optical properties and structure of ZBLAN glasses, and also the effects produced in these properties after ultra-short laser irradiation. Chromium ions with 3d 2 configurations are of interest for solid state laser materials due to their ability to generate laser emission in the near infrared spectral region between 1.2 and 1.7 mm [5]. Among various transition metal ions, chromium ion is a paramagnetic ion that, when dissolved in glass matrices in very small amounts, strongly affects the optical transmission and the insulating strength of the glasses. Over the past several years, Tm 3+ -doped glasses have been widely investigated since Tm 3+ -doped ARTICLE IN PRESS www.elsevier.com/locate/jpcs 0022-3697/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.jpcs.2007.07.125 Ã Corresponding author. Tel.: +55 11 40436425; fax: +55 11 38169315. E-mail addresses: lcourrol@gmail.com, lcourrol@unifesp.br (L.C. Courrol).