Spectroscopic properties of Yb3+ doped PbO-Bi2O3-Ga2O3 glasses for IR laser applications

PbO-Bi2O3-Ga2O3 glasses doped with different concentrations of Yb3+ are presented. The spectroscopic properties and laser parameters are calculated and a comparison between different results obtained when calculating the Yb3+ emission cross-section with the reciprocity method and with the Fuchtbauer-Ladenburg formula is presented. The behavior of the near-infrared luminescence is described theoretically by a rate equation and compared with the experimental results. This host doped with Yb3+ is a promising material for laser action at 1019 nm, with properties similar to other known glasses used as active laser media; the emission cross-section of 1.1 x 10(-20) cm(2), the high absorption cross-section (of 2.0 x 10(-20) cm(2)) and a minimum pump intensity of 2.4 kW/cm(2) are interesting properties for short pulse generation. (C) 2005 Elsevier B.V. All rights reserved.

Raman spectroscopy analysis of structural photoinduced changes in GeS2 + Ga2O3 thin films

Photoexpansion and photobleaching effects have been observed in amorphous GeS2 + Ga2O3 (GGSO) thin films, when their surfaces were exposed to UV light. The photoinduced changes on the surface of the samples are indications that the structure has been changed as a result of photoexcitation. In this paper, micro-Raman, energy dispersive X-ray analysis (EDX) and backscattering electrons (BSE) microscopy were the techniques used to identify the origin of these effects. Raman spectra revealed that these phenomena are a consequence of the Ge-S bonds' breakdown and the formation of new Ge-O bonds, with an increase of the modes associated with Ge-O-Ge bonds and mixed oxysulphide tetrahedral units (S-Ge-O). The chemical composition measured by EDX and BSE microscopy images indicated that the irradiated area is oxygen rich. So, the present paper provides fundamental insights into the influence of the oxygen within the glass matrix on the considered photoinduced effects. (C) 2010 Elsevier B.V. All rights reserved.

Photoexpansion and photobleaching effects in oxysulfide thin films of the GeS2+Ga2O3 system

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of the ytterbium concentration on the upconversion luminescence of Yb3+/Er3+ co-doped PbO-GeO2-Ga2O3 glasses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

IR-visible upconversion and thermal effects in Pr3+/Yb3+-codoped Ga2O3 : La2S3 chalcogenide glasses

IR-visible upconversion fluorescence spectroscopy and thermal effects in pr(3+)/Yb3+-codoped Ga2O3:La2S3 chalcogenide glasses excited at 1.064 mum is reported. Intense visible upconversion emission in the wavelength region of 480-680 nm peaked around 500, 550, 620 and 660 nm is observed. Upconversion excitation of the Pr3+ excited-state visible emitting levels is achieved by st combination of phonon-assisted absorption, energy-transfer and phonon-assisted excited-state absorption processes. A threefold upconversion emission enhancement induced by thermal effects when the codoped sample was heated in the temperature range of 20-200 degreesC is demonstrated. The thermal-induced enhancement is attributed to a multiphonon-assisted anti-Stokes process which takes place in the excitation of the ytterbium and excited-state absorption of the praseodymium. The thermal effect is modelled by conventional rate equations considering temperature-dependent effective absorption cross-sections for the F-2(7/2)-F-2(5/2) ytterbium transition and (1)G(4)-P-3(0) praseadymium excited-state absorption, and it is shown to agree very well with experimental results. Frequency upconversion in singly Pr3+-doped samples pumped at 836 nm and 1.064 mum in a two-beam configuration is also examined.

Study of the most suitable new glass laser to incorporate ytterbium: alkali niobium tellurite, lead fluorborate or heavy metal oxide

Diode-pumped Yb-doped glass lasers have received considerable attention for applications such as high-power beam production or femtosecond pulses generation. In this paper, we evaluate the laser potential of three different glass families doped with Yb3+ : alkali lead fluorborate (PbO-PbF2-B2O3), heavy metal oxide (Bi2O3-PbO-Ga2O3) and niobium tellurite (TeO2-Nb2O5-K2O-Li2O). Spectroscopic properties were studied for the samples and calculations of the minimum laser pump intensity (I-min), saturation fluence (U-sat) and the theoretical limit of peak power (P-max) are also presented. A comparison of laser properties of these three different glasses and their importance is shown and analyzed. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Spectroscopic properties of Er3+ in oxysulfide glasses

Er3+ -containing gallium-lanthanum oxysulfide glasses have been prepared from Ga2O3 and La2S3 in a sulfur/argon reactive atmosphere. The samples have been characterized by absorption and emission spectroscopy and IR emission kinetics. Er3+ electronic transition intensities have been analyzed in the light of the Judd-Ofelt formalism, and quantum efficiencies evaluated for the Er3+ emission at 1.5 and 2.7 mum. The results so obtained suggest that these glasses display favorable properties concerning IR optical applications. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Evaluation of laser level populations of erbium-doped glasses

A simulation of erbium-doped glass systems, which provides population density for the excited states involved in the 1.5 mu m and also for 2.7 mu m emissions when pumped around 980 nm, is presented. To describe the diode pump laser processes, a theoretical model based in a coupled system of differential rate equations was developed. The approach used and the obtained spectroscopic parameters are discussed. The materials under study are two oxide glasses, lead fluoroborate (PbO-PbF2-B2O3), and heavy metal oxide (Bi2O3 PbO-Ga2O3) and a fluoride glass (ZrF4-BaF2-LaF3-AlF3-NaF), all of them doped with Er3+. (c) 2006 Elsevier B.V. All rights reserved.

Preparação e estudo termoanalítico dos 2-clorobenzalpiruvatos de alumínio, de gálio, de índio e de escândio no estado sólido

Pós-graduação em Química - IQ