المؤلفون: Chiasera, A.¹ achiaser@science.unitn.it, Armellini, C.¹, Bhaktha, S.N.B.^1,2, Chiappini, A.¹, Jestin, Y.¹, Ferrari, M.¹, Moser, E.², Coppa, A.³, Foglietti, V.³, Huy, P.T.⁴, Tran Ngoc, K.⁴, Nunzi Conti, G.^5,6, Pelli, S.⁶, Righini, G.C.^6,7, Speranza, G.⁸

المصدر: Journal of Non-Crystalline Solids. Jul2009, Vol. 355 Issue 18-21, p1176-1179. 4p.

مصطلحات موضوعية: *WAVEGUIDES, *SILICA, *HAFNIUM oxide, *SPUTTERING (Physics), *RADIO frequency, *OPTICAL properties, *X-ray spectroscopy

مستخلص: Abstract: 95.8SiO2–4.2HfO2 planar waveguide activated by 0.2mol% Er and 0.2mol% Yb was fabricated by multi-target rf-sputtering technique. The optical parameters were measured by an m-line apparatus operating at 543.5, 632.8, 1319 and 1542nm. The waveguide compositions were investigated by energy dispersive spectroscopy. The waveguide exhibits a single propagation mode at 1.3 and 1.5μm with an attenuation coefficient of 0.2dB/cm at 1.5μm. The emission of 4I13/2 → 4I15/2 transition of Er3+ ion, with a 42nm bandwidth was observed upon TE0 mode excitation at 980 and 514.5nm. Photoluminescence excitation spectroscopy was used to obtain information about the effective excitation efficiency of Er3+ ions by co-doping with Yb3+ ions. Channel waveguide in rib configuration were fabricated by wet etching process in the active film. [Copyright &y& Elsevier]

المؤلفون: Chiappini, A.¹, Armellini, C.¹, Chiasera, A.¹, Ferrari, M.¹, Guider, R.², Jestin, Y.¹, Minati, L.³, Moser, E.⁴, Nunzi Conti, G.⁵, Pelli, S.⁵, Retoux, R.⁶, Righini, G.C.^5,7, Speranza, G.³

المصدر: Journal of Non-Crystalline Solids. Jul2009, Vol. 355 Issue 18-21, p1132-1135. 4p.

مصطلحات موضوعية: *ZINC oxide, *NANOPARTICLES, *WAVEGUIDES, *SILANE compounds, *GELATION, *SUBSTRATES (Materials science), *SILICA, *OPTICAL properties

مستخلص: Abstract: Hybrid organic–inorganic waveguides based on ZnO-(3-glycidoxypropil)trimethoxisilane (GPTS) have been fabricated by sol–gel route. A transparent sol of ZnO was added to the GPTS host and the resulting sol was deposited on silica substrates by spin coating technique. Waveguides with different molar composition (100−x)GPTS−xZnO (x =10, 20, 30) were investigated by different diagnostic techniques. Morphological measurements were carried out by means of an AFM apparatus, and a roughness of few nanometers was estimated for all the waveguides. Optical properties such as refractive index, thickness, number of propagating modes and attenuation coefficient were measured at 632.8, 543.5, 1319 and 1542nm by the prism coupling technique as a function of the ZnO content. Photoluminescence measurements, upon excitation at 325nm, showed a large luminescence band in the region between 350 and 600nm with a main peak centered at about 380nm, due to the presence of ZnO nanoparticles. [Copyright &y& Elsevier]

المؤلفون: Speranza, G.¹ speranza@fbk.eu, Minati, L.¹, Chiasera, A.², Chiappini, A.², Jestin, Y.², Ferrari, M.², Righini, G.C.^3,4

المصدر: Journal of Non-Crystalline Solids. Jul2009, Vol. 355 Issue 18-21, p1157-1159. 3p.

مصطلحات موضوعية: *PHOTONS, *STRUCTURAL analysis (Science), *X-ray photoelectron spectroscopy, *WAVEGUIDES, *NANOSTRUCTURES, *CERAMIC materials

مستخلص: Abstract: This work deals with X-ray photoemitted spectra (XPS) from materials which are of interest for photonic applications. In particular xHfO2 −(100− x) SiO2 (x =10, 20, 30mol%) glass–ceramics planar waveguides and silver ion-exchanged (0.5, 1.5, 5mol%) sodalime glasses are investigated. The aim of the work is to explore the material structural changes occurring at the nanometric scale which are produced during the fabrication process in order to enlighten the formation of the nanostructures. The results show that XPS is sufficiently sensitive to detect the formation of nanostructures in the analyzed materials providing at the same time also chemical information. Both these inputs are important to tune the production processes to increase the efficiency of the optical devices. [Copyright &y& Elsevier]

المؤلفون: Minati, L.¹ luminati@itc.it, Speranza, G.¹, Ferrari, M.², Jestin, Y.², Chiasera, A.²

المصدر: Journal of Non-Crystalline Solids. Apr2007, Vol. 353 Issue 5-7, p502-505. 4p.

مصطلحات موضوعية: *SILICON compounds, *SPECTRUM analysis, *WAVEGUIDES, *ELECTRON spectroscopy

مستخلص: Abstract: X-ray photoelectron spectroscopy (XPS) has been used in the study of sol gel-derived Er3+-activated xHfO2–(100− x)SiO2 (x =10, 20, 30, 40, 50mol) planar waveguides. The analysis of Si 2p and O 1s core lines were related to the Hf/Si molar ratio to assess the role of hafnia in modifying the silica network. Increasing the HfO2 content brings about a change of the Si 2p and O 1s binding energy respect to those from pure silica. This trend is explained with a formation of hafnium silicate in the matrix with successive phase separation between HfO2 and SiO2 rich phases. XPS results show that hafnia is well dispersed in the silica matrix for molar concentration below 30%. Formation of pure HfO2 domains was detected at higher hafnia concentrations in agreement with previous spectroscopic analyses. [Copyright &y& Elsevier]

المؤلفون: Jestin, Y.¹ jestin@science.unitn.it, Armellini, C.¹, Chiappini, A.², Chiasera, A.¹, Ferrari, M.¹, Goyes, C.¹, Montagna, M.², Moser, E.², Nunzi Conti, G.³, Pelli, S.³, Retoux, R.⁴, Righini, G.C.⁵, Speranza, G.⁶

المصدر: Journal of Non-Crystalline Solids. Apr2007, Vol. 353 Issue 5-7, p494-497. 4p.

مصطلحات موضوعية: *CONSTRUCTION materials, *INDUSTRIAL chemistry, *WAVEGUIDES, *NANOCRYSTALS

مستخلص: Abstract: (100− x)SiO2 − xHfO2 (x =10, 20, 30mol) glass–ceramics planar waveguides activated by 0.3mol% Er3+ ions were prepared by sol–gel route, using dip-coating deposition on v-SiO2 substrates. High resolution transmission electron microscopy has shown that after an adapted heat treatment, the resulting materials show nanocrystalline structures. The glass–ceramics waveguides were characterized by m-line, Raman, losses measurements, and photoluminescence spectroscopy. Photoluminescence spectroscopy has demonstrated the embedding of erbium ions in the nanocrystals. The results are discussed with the aim of assessing the role of hafnia on the structural, optical and spectroscopic properties of erbium doped silica hafnia glass–ceramics planar waveguides. [Copyright &y& Elsevier]

المؤلفون: Zampedri, L.^1,2 zampedri@science.unitn.it, Righini, G.C.³, Portales, H.⁴, Pelli, S.³, Nunzi Conti, G.³, Montagna, M.⁵, Mattarelli, M.⁵, Gonçalves, R.R.^1,2, Ferrari, M.¹, Chiasera, A.⁵, Bouazaoui, M.⁶, Armellini, C.¹

المصدر: Journal of Non-Crystalline Solids. Oct2004, Vol. 345-346, p580-584. 5p.

مصطلحات موضوعية: *COLLOIDS, *SILICON compounds, *SPECTRUM analysis, *WAVEGUIDES

مستخلص: Abstract: (100−x)SiO2–xHfO2 (x=10,20,30,40mol) planar waveguides, doped with 0.3mol% Er3+ ions were prepared by the sol–gel route, using dip-coating deposition on v-SiO2 substrates. The waveguides were characterized by m-line, Raman and photoluminescence spectroscopies. The results are discussed with the aim of assessing the role of hafnia on the structural, optical and spectroscopic properties of the erbium-doped silica-hafnia planar waveguides. The spectral bandwidth of the 4I13/2→4I15/2 transition does not change practically with the hafnium content. The 4I13/2 level decay curves present a single-exponential profile, with a lifetime between 5.5 and 7.1ms, depending on the HfO2 concentration. [Copyright &y& Elsevier]