Superbroadband near-IR photoluminescence from Pr³⁺-doped fluorotellurite glasses

Author name used in this publication: Yuen H. Tsang2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Spectroscopic Properties of Inorganic Glasses Doped with Pr3+: A Comparative Study

The results presented in this communication concern visible and near-IR emission of Pr3+ ions in selected inorganic glasses, i.e., borate-based glass with Ga2O3 and BaO, lead-phosphate glass with Ga2O3, gallo-germanate glass modified by BaO/BaF2, and multicomponent fluoride glass based on InF3. Glasses present several emission bands at blue, reddish orange, and near-infrared spectral ranges, which correspond to 4f–4f electronic transitions of Pr3+. The profiles of emission bands and their relative intensity ratios depend strongly on glass-host. Visible emission of Pr3+ ions is tuned from red/orange for borate-based glass to nearly white light for multicomponent fluoride glass based on InF3. The positions and spectral linewidths for near-infrared luminescence bands at the optical telecommunication window corresponding to the 1G4 → 3H5, 1D2 → 1G4, and 3H4 → 3F3,3F4 transitions of Pr3+ are dependent on glass-host matrices and excitation wavelengths. Low-phonon fluoride glasses based on InF3 and gallo-germanate glasses with BaO/BaF2 are excellent candidates for broadband near-infrared optical amplifiers. Spectroscopic properties of Pr3+-doped glasses are compared and discussed in relation to potential optical applications

Guides d'onde en verres et vitrocéramiques fluorés dopés terre rare élaborés par PVD pour l'émission dans le visible et la conversion de fréquence

Le projet s inscrit dans le développement de sources lasers RGB miniaturisées pour l affichage et la vidéoprojection, la conversion de fréquence dans les cellules solaires.Les verres fluorés ZLAG (ZrF4-LaF3-AlF3-GaF3) codopés terres rares ont été considérés. Ce verre possède une faible énergie de phonon, une forte solubilité des terres rares et peut être fabriqué en couche mince par la technique PVD. Il est de plus le précurseur de vitrocéramiques transparentes. On a observé dans les verres massifs et les guides d onde des émissions bleue, orange et rouge avec un codopage Pr3+-Yb3+, bleue et rouge avec un co-dopage Tm3+-Yb3+. L émission RGB dans les verres tri-dopés Tm3+-Er3+-Yb3+ semble prometteuse. Par ailleurs, la vitro-céramisation a permis d augmenter de plus de 30% les sections efficaces d absorption des ions Pr3+ et Yb3+.Une efficacité de transfert de 92% a été obtenue dans les verres co-dopés 0,5Pr3+-10Yb3+ pour le processus de conversion d un photon bleu en deux photons IR.The project joins in the development of miniaturized laser sources RGB for display and videoprojection, frequency conversion in solar cells.Fluoride glasses ZLAG ( ZrF4-LaF3-AlF3-GaF3) co-doped with rare earths were studied. This glass has a low phonon energy, a strong solubility of the rare earth ions and can be fabricated as thin films by PVD. It is also the precursor of transparent glass-ceramics. Similar emissions in both co-doped bulk and waveguides have been observed ; blue, orange, red emission for Pr3+-Yb3+ and blue, red emission for Tm3+-Yb3+. The RGB emission in bulk Tm3+-Er3+-Yb3+ tri-doped glass seems promising. Furthermore, the absorption cross section of Pr3+ and Yb3+ ions has been increased by 30% with the ceraming process.An energy transfer efficiency (ETE) of 92% has been obtained for co-doped glass with 0,5Pr3+-10Yb3+ for the conversion process of a blue photon into two infrared one.LE MANS-BU Sciences (721812109) / SudocSudocFranceF

Numerical and experimental investigation of novel materials for laser and amplifier operations

One of the most exciting areas of research in optics is rare-earth doped glasses and fibres with capacity for near-infrared to mid-infrared operations. In particular, there is great interest in optimising parameters like ion concentration, fibre length/geometry, and pump conditions for applications in photoluminescence, amplification and lasing. Round trip investigation from material fabrication, experimental setup and actual device can be laborious, expensive and come with some uncertainties. Some of these uncertainties are accurate identification of ion-ion interactions, impact of such interactions on device performance, correct extraction of phenomenological material properties and the prediction of combination of properties with numerical methods. In this thesis, the spectroscopic behaviour of rare-earth doped materials are theoretically studied via numerical simulations and experimentally verified. The models developed are applicable to steady-state and transient behaviour of rare-earths under different excitation conditions. For the simulation, a couple of spectroscopic parameters are needed which have to be obtained in advance from bulk glasses. Parameters like radiative and non-radiative lifetimes are calculated by complementing theoretical analysis with a few experimental measurements. The first part of the research concentrates on the study of ion-ion interactions in different concentrations of erbium doped sol-gel SiO2 prepared by the sol-gel method. The work includes continuous-wave (CW) and pulsed excitation spectroscopic measurement on the glasses that provide data for the model. These measurements together with the rate-equation modelling are used to obtain a physical understanding of the processes responsible for the fluorescence features observed. A particle swarm optimisation technique was used to predict the values of the ion-ion interactions. The behaviour of the 488 nm and 800 nm excitations were consistent with the predictions of the model. Indeed, the agreement between the calculated photoluminescence and the measured emission indicates that the six important processes that influence the ion-ion interactions in the bulk material have been correctly identified and included. With this model of photoluminescence at hand, it was possible to extend it to laser or amplifier configurations. Subsequently, erbium doped ZBLAN glass fibre with lower phonon energy were explored for lasing in the mid-infrared for application to 2.73 µm high-power delivery for tissue surgery. Accurate laser characteristics were predicted for two different designs, including the ultimate thermal designs. Optimum boundary conditions of mirror end-facet reflectivity, fibre length and effects of modelling parameters were addressed. The study is complimented with experimental data of double-clad fibre and the results reported were a clear documentation of the design of erbium doped ZBLAN fiber laser. Finally, the potential of P r3+ doped chalcogenide (GeAs(Ga/In)Se) glass for photoluminescence and lasing at 4.73 µm is studied. This is to answer the research question - Can we extract the spectroscopic parameters and also model the superior property of these novel glasses?. The laboratory facilities and availability of experimental data were decisive in the choice of praseodymium ions as well as inclusion of Gallium or Indium for this part of the research. The superior characteristics of Indium over Gallium for hotoluminescence and consequently device characteristics were studied with the aid of a rate equation model. The phenomenon of photon reabsorption in the chalcogenide fibres were also simulated and verified with experiment. The work has produced a comprehensive numerical model for the simulation of photoluminescence in P r3+doped selenide based chalcogenide glass and fibre from NIR to mid-IR especially in the Gallium and Indium based analogues

Numerical and experimental investigation of novel materials for laser and amplifier operations

One of the most exciting areas of research in optics is rare-earth doped glasses and fibres with capacity for near-infrared to mid-infrared operations. In particular, there is great interest in optimising parameters like ion concentration, fibre length/geometry, and pump conditions for applications in photoluminescence, amplification and lasing. Round trip investigation from material fabrication, experimental setup and actual device can be laborious, expensive and come with some uncertainties. Some of these uncertainties are accurate identification of ion-ion interactions, impact of such interactions on device performance, correct extraction of phenomenological material properties and the prediction of combination of properties with numerical methods. In this thesis, the spectroscopic behaviour of rare-earth doped materials are theoretically studied via numerical simulations and experimentally verified. The models developed are applicable to steady-state and transient behaviour of rare-earths under different excitation conditions. For the simulation, a couple of spectroscopic parameters are needed which have to be obtained in advance from bulk glasses. Parameters like radiative and non-radiative lifetimes are calculated by complementing theoretical analysis with a few experimental measurements. The first part of the research concentrates on the study of ion-ion interactions in different concentrations of erbium doped sol-gel SiO2 prepared by the sol-gel method. The work includes continuous-wave (CW) and pulsed excitation spectroscopic measurement on the glasses that provide data for the model. These measurements together with the rate-equation modelling are used to obtain a physical understanding of the processes responsible for the fluorescence features observed. A particle swarm optimisation technique was used to predict the values of the ion-ion interactions. The behaviour of the 488 nm and 800 nm excitations were consistent with the predictions of the model. Indeed, the agreement between the calculated photoluminescence and the measured emission indicates that the six important processes that influence the ion-ion interactions in the bulk material have been correctly identified and included. With this model of photoluminescence at hand, it was possible to extend it to laser or amplifier configurations. Subsequently, erbium doped ZBLAN glass fibre with lower phonon energy were explored for lasing in the mid-infrared for application to 2.73 µm high-power delivery for tissue surgery. Accurate laser characteristics were predicted for two different designs, including the ultimate thermal designs. Optimum boundary conditions of mirror end-facet reflectivity, fibre length and effects of modelling parameters were addressed. The study is complimented with experimental data of double-clad fibre and the results reported were a clear documentation of the design of erbium doped ZBLAN fiber laser. Finally, the potential of P r3+ doped chalcogenide (GeAs(Ga/In)Se) glass for photoluminescence and lasing at 4.73 µm is studied. This is to answer the research question - Can we extract the spectroscopic parameters and also model the superior property of these novel glasses?. The laboratory facilities and availability of experimental data were decisive in the choice of praseodymium ions as well as inclusion of Gallium or Indium for this part of the research. The superior characteristics of Indium over Gallium for hotoluminescence and consequently device characteristics were studied with the aid of a rate equation model. The phenomenon of photon reabsorption in the chalcogenide fibres were also simulated and verified with experiment. The work has produced a comprehensive numerical model for the simulation of photoluminescence in P r3+doped selenide based chalcogenide glass and fibre from NIR to mid-IR especially in the Gallium and Indium based analogues

Verres et vitrocéramiques fluorés dopés terre rare et/ou métal de transition pour la conversion de l'énergie solaire

The efficiency of solar cells can be improved by fully exploiting the UV-blue portion of the solar spectrum, through a frequency converting mechanism of type downconversion. This process using energy transfer between rare earth ions (RE) or 3d transition metal (pairs RE3+/Yb3+ with TR = Pr, Tm,… and Cr3+/Yb3+) requires a matrix with low phonon energy to reduce non radiative relaxation.So far, the studied materials are mainly in the form of polycristalline powder, which limits their use due to diffusion or single crystals which manufacturing cost is high.As part of this thesis, fluoride glasses based on fluorozirconate ZLAG (ZrF4-LaF3-AlF3-GaF3) and ZBLA (ZrF4-LaF2-LaF3-AlF3) have been prepared by the melting-casting technique. These are suitable because of their intrinsic properties of transparency and low phonon energy. The resulting materials were then characterized by thermal analysis, X-ray diffraction, transmission electron microscopy and luminescence.Molecular Dynamics simulation and Fluorescence line narrowing of ZLAG matrix have been performed in order to investigate the structural modification during the transformation of the glass into the glass-ceramic.Luminescence of Yb3+ ion was observed in the near IR at 980 nm under blue excitation in all studied series, which is the signature of energy transfer. In the ZLAG glass, the efficiency reaches 92% for Pr3+ → Yb3+ energy transfer and 65% for Tm3+ → Yb3+ energy transfer. The efficiency is lower in the ZBLA glass and the ZLAG ceramisation does not improve the performances.L’efficacité des cellules solaires peut être améliorée en exploitant pleinement la partie UV-bleue du spectre solaire, par un mécanisme de conversion de fréquence de type down-conversion. Ce processus utilisant des transferts d’énergie entre ions de terre rare (TR) ou métal de transition 3d (paires TR3+/Yb3+ avec TR = Pr, Tm,… et Cr3+/Yb3+) requiert des matrices à basse énergie de phonon pour réduire les relaxations non radiatives.Jusqu’à présent, les matériaux étudiés sont principalement sous forme de poudre polycristalline, ce qui limite leur utilisation à cause de la diffusion, ou de monocristaux dont le coût de fabrication est élevé.Dans le cadre de cette thèse, les verres fluorés à base de fluorozirconate ZLAG (ZrF4-LaF3-AlF3-GaF3) et ZBLA (ZrF4-BaF2-LaF3-AlF3) ont été préparés par la technique de fusion-coulée. Ces derniers sont adaptés du fait de leurs propriétés intrinsèques de transparence et de leur faible énergie de phonon. Les matériaux obtenus ont ensuite été caractérisés par, analyse thermique, diffraction des rayons X, microscopie électronique à transmission et luminescence.Des études par dynamique moléculaire et fluorescence par affinement de raies ont été effectuées sur la matrice ZLAG afin de suivre les modifications structurales lors du passage du verre à la vitrocéramique.La luminescence de l’ion Yb3+ a été observée dans l’infra-rouge à 980 nm sous excitation bleue dans toutes les séries étudiées, signature d’un transfert d’énergie. ans le verre ZLAG, l’efficacité atteint 92% pour le transfert d’énergie Pr3+ → Yb3+ et 65% pour le transfert d’énergie Tm3+ → Yb3+. L’efficacité est plus faible dans le verre ZBLA et la vitrocéramisation du verre ZLAG n’améliore pas les performances

Computational and Experimental Investigations Concerning Rare Gas and DPAL Lasers and a Relaxation Kinetics Investigation of the Br\u3csub\u3e2\u3c/sub\u3e + 2NO = 2BrNO Equilibrium

This research contains four different research projects, the first an educational project introducing hydrogen bromide and deuterium bromide (HBr/DBr) and carbon monoxide (CO) as viable options for infrared vibration-rotation spectroscopy at 0.125 cm-1 or 0.5 cm-1 resolution in the teaching laboratory. The second project involved determining the spectral shifts of lanthanide fibers for diode-pumped alkali laser (DPAL) applications. Spectral shifts of lanthanides were determined using UV-VIS-NIR absorbance spectroscopy and laser-induced fluorescence (LIF). The third project entailed computing Ar* atomic energy levels and the potential energy curves of Ar*+He laser systems arising from 3p54s1 and 3p54p1 Ar* electronic configurations using ab initio theory. The final project of this research determined rate coefficients and the equilibrium constant of the formation of nitrosyl bromide (BrNO) using relaxation kinetics. Integrated solution of the relaxation rate equation and third-order integrated rate law methodologies produced final values of kf = 1.50(6) x 10-5 torr-2s-1, kr = 5.8(8) x 10-5 torr-1s-1, and Keq = 0.26(3) torr-1, agreeing with literature within uncertainty

Development of a Tm3+-doped flouride glass optical fibre laser for gas sensing

The development of a fluoride fibre laser for hydrocarbon gas sensing is discussed. The use of a fibre laser as a source for optical sensing has many advantages including small size and ease of adaptability into industrial systems. The fibre laser constructed in this work has an operating wavelength of X = 2.3 n.m, which corresponds to an absorption band of many hydrocarbon gases. The thulium-doped fibre has been fully characterised in terms of absorption, fluorescence and fluorescence lifetimes. These data were then used to choose a pump laser diode and appropriate laser mirrors. The operational fibre laser was fully characterised in terms of output power and slope efficiency. Two fibre laser configurations were demonstrated. The first fibre laser exhibited a dual laser emission simultaneously at 1.92 p.m and 2.31 urn, with output powers of 7 mW and 1.2 mW, respectively. A second fibre laser was also demonstrated; this device was optically pumped with a low power laser diode. The output from the fibre laser pumped by the low power laser diode was utilised as a unique source for detection of methane. A detection limit of 1000 ppm metres was routinely demonstrated with this unoptimised system