Upconversion ultraviolet random lasing in Nd 3+ doped fluoroindate glass powder

An upconversion random laser (RL) operating in the ultraviolet is reported for Nd 3+ doped fluoroindate glass powder pumped at 575 nm. The RL is obtained by the resonant excitation of the Nd 3+ state 2G 7/2 followed by energy transfer among two excited ions such that one ion in the pair decays to a lower energy state and the other is promoted to state 4D 7/2 from where it decays emitting light at 381 nm. The RL threshold of 30 kW/cm 2 was determined by monitoring the photoluminescence intensity as a function of the pump laser intensity. The RL pulses have time duration of 29 ns that is 50 times smaller than the decay time of the upconversion signal when the sample is pumped with intensities below the RL laser threshold. © 2011 Optical Society of America.

Upconversion luminescence in Er3+ doped Ga10Ge 25S65 glass and glass-ceramic excited in the near-infrared

The infrared-to-visible frequency upconversion was investigated in Er 3+-doped Ga10Ge25S65 glass and in the transparent glass-ceramic obtained by heat-treatment of the glass above its glass-transition temperature. Continuous-wave and pulsed lasers operating at 980 nm and 1480 nm were used as excitation sources. The green (2H 11/2 → 4I15/2; 4S3/2 → 4I15/2) and red (4F9/2 → 4I15/2) photoluminescence (PL) signals due to the Er3+ ions were characterized. The PL decay times were influenced by energy transfer among Er3+ ions, by cross-relaxation processes and by energy transfer from the Er3+ ions to the host material. The PL from the Er3+ ions hosted in the crystalline phase was distinguished only when the glass-ceramic was excited by the 1480 nm pulsed laser. The excitation pathways responsible for the green and red PL bands are discussed to explain the differences between the spectra observed under continuous-wave and pulsed excitation. © 2013 American Institute of Physics.

Avaliação da resistência de união entre dentina preparada por laser e um sistema adesivo a base de silorano, variando a técnica de aplicação e umidade do substrato

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modificação de superfícies de zircônia empregada a restaurações sem metais

Pós-graduação em Química - IQ

Modificação de superfície empregando-se laser e recobrimento de implantes dentários de titânio com apatitas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação do laser de erbio na infiltração marginal em cicatrículas e fissuras oclusais após selamento

Pós-graduação em Ciência Odontólogica - FOA

Application of Er:YAG and Er, Cr:YSGG lasers in cavity preparation for dental tissues: a literature review

The laser has been widely used in many specialties of dentistry and several wavelengths have been investigated as a substitute for high-speed handpiece. The purpose of this paper is to review the literature about the use of Er:YAG and Er,Cr:YSGG lasers in cavity preparation for dental tissues. Despite the differences in wavelength, pulse duration and energy, the morphological characteristics of the irradiated dentin surface with these lasers are comparable, as well as its effects as methods of dental caries prevention. Thus, Er:YAG and Er,Cr:YSGG lasers prepared cavities with similar effects on the dental tissue, however, further investigations about ideal irradiation conditions are needed for both lasers.

Repair of composites: Effect of laser and different surface treatments

Objectives: This study investigated the repairs of resin composite restorations after using different surface treatments.Design: Eighty four truncated cones of Filtek Z350 were prepared and thermo-cycled (20,000 cycles). Surfaces were roughened with diamond bur and etched with 37% phosphoric acid. Those cones were divided into 7 groups (N=12): 1) Prime&Bond 2.1; 2) aluminum oxide sandblasting+Prime&Bond 2.1; 3) Er:YAG laser treatment+Prime&Bond 2.1; 4) 9.6% hydrofluoric acid for 2 min-Fsilane coupling agent.; 5) silane coupling agent; 6) auto-polymerized acrylic monomer+Prime&Bond 2.1; 7) Adper Scothbond SE. Teflon device was used to fabricate inverted truncated cones of repair composite over the surface-treated. The bonded specimens were stressed to failure under tension. The data were analyzed with oneway ANOVA and Tukey tests.Results: Mean repair strengths (SD, in MPa) were, Group-2: 18.8a; Group-1: 18.7a; Group-6: 13.4ab; Group-7: 9.5bc; Group-3: 7.5bcd; Group-4: 5.2cd; Group-5: 2.6d.Conclusions: The use of diamond bur and a conventional adhesive and the use of aluminum oxide sandblasting prior to adhesive provided a simple and cost-effective solutions to composite repair. Er:YAG laser, silane alone, 9.6% hydrofluoric acid plus silane or a self-etching adhesive results in inferior composite repair strengths. (C) 2015 Elsevier Ltd. All rights reserved.