4TH BRAZILIAN MRS MEETING Thermal-lens study of thermo-optical properties of tellurite glasses V. Pilla E. F. Chillcce A. A. R. Neves E. Munin T. Catunda C. L. Cesar L. C. Barbosa Received: 4 November 2005 / Accepted: 10 April 2006 / Published online: 23 January 2007 Ó Springer Science+Business Media, LLC 2007 Abstract Mode-mismatched Thermal Lens (TL) measurements were performed in 70TeO 2 –19WO 3 – 7Na 2 O–4Nb 2 O 5 (% mol) tellurite glasses doped with either Er 3+ or Tm 3+ and co-doped with Er 3+ /Tm 3+ ions. Thermo-optical parameters (D, K,ds/dQ and ds/dT) were obtained in function of thulium concentrations (0.39–1.6) · 10 20 ions/cm 3 . For Er 3+ /Tm 3+ co-doped tellurite glasses, D and K values are practically independent of the Tm 3+ concentrations used in this study. The average values of D and ds/dT obtained for tellurite glasses are: (3.1 ± 0.2) · 10 –3 cm 2 /s and (16 ± 3) · 10 –6 K –1 , respectively. Introduction Tellurite glass has been receiving special attention because it possesses interesting properties as: high rare earth ions solubility, higher refractive indices than both the silicates and fluoride glasses, and large amplifica- tion bandwidth. In this way, tellurite glasses are becoming promising for practical applications as: optical amplifiers, optical recording, laser active media and infrared-to-visible converters [1–6]. The studies of these optical materials are driven by a strong interest do gather fundamental material properties that could lead to the development of new solid-state short- wavelength laser. For example, Er 3+ /Eu 3+ co-doped tellurite fibre presents visible emission [5], being a potential host material for satellite communication at 589 nm and a compact fibre laser for medical applica- tion at 613 nm. In addition, Er 3+ /Tm 3+ co-doped tellurite glasses present blue up-conversion, as the Er 3+ ion plays the role of a selective sensitizer for the Tm 3+ ion [6]. In this way, the characterizations of the nonlinear optical and thermo-optical properties of the tellurite glasses are very important for the optimi- zation of the applications of these materials. The characterization of the thermooptic properties is fundamental for the determination of the thermo- mechanical figure of merit of optical materials. In this form, it becomes possible to determine parameters as: thermal-shock, thermal fracture resistance and thermal lens effect [7–9]. The thermal diffusivity (D) and thermal conductivity (K) measure the rate of change of temperature in a transient heat transfer process. Usually, D and K are dependent upon processing condition and the compositional and structural prop- erties of the glass. For instance, the improvement of a laser material performance, a high thermal conductiv- ity is desirable to dissipate the heat from regions in which generation of laser light occurs. On the other hand, the optical path S (cm) of the glass with refractive index n and thickness L is dependent on the temperature (S(T)= n(T) L(T)) and the thermally V. Pilla (&)  E. Munin Instituto de Pesquisa e Desenvolvimento- IPD, Universidade do Vale do Paraı´ba- Univap, Sa ˜o Jose ´ dos Campos 12244-000, SP, Brazil e-mail: vpilla@univap.br E. F. Chillcce  A. A. R. Neves  C. L. Cesar  L. C. Barbosa Instituto de Fı´sica Gleb Wataghin, Universidade Estadual de Campinas- Unicamp, Campinas 13083-970, SP, Brazil T. Catunda Instituto de Fı´sica de Sa ˜ o Carlos, Universidade de Sa ˜o Paulo- Usp, Sa ˜ o Carlos 13560-970, SP, Brazil J Mater Sci (2007) 42:2304–2308 DOI 10.1007/s10853-006-0180-y 123