Abstract
Glasses in the ternary system (70 - x)NaPO(3)-30WO(3)-xBi(2)O(3), with x = 0-30 mol %, were prepared by the conventional melt-quenching technique. X-ray diffraction (XRD) measurements were performed to confirm the noncrystalline nature of the samples. The influence of the Bi(2)O(3) on the thermal, structural, and optical properties was investigated. Differential scanning calorimetry analysis showed that the glass transition temperature, T(g), increases from 405 to 440 °C for 0 ≤ x ≤ 15 mol % and decreases to 417 °C for x = 30 mol %. The thermal stability against devitrification decreases from 156 to 67 °C with the increase of the Bi(2)O(3) content. The structural modifications were studied by Raman scattering, showing a bismuth insertion into the phosphate chains by Bi-O-P linkage. Furthermore, up to 15 mol % of Bi(2)O(3) formation of BiO(6) clusters is observed, associated with Bi-O-Bi linkage, resulting in a progressive break of the linear phosphate chains that leads to orthophosphate Q(0) units. The linear refractive index, n(0), was measured using the prism-coupler technique at 532, 633, and 1550 nm, whereas the nonlinear (NL) refractive index, n(2) was measured at 1064 nm using the Z-scan technique. Values of 1.58 ≤ n(0) ≤ 1.88, n(2) ≥ 10(-15) cm(2)/W and NL absorption coefficient, α(2) ≤ 0.01 cm/GW, were determined. The linear and NL refractive indices increase with the increase of the Bi(2)O(3) concentration. The large values of n(0) and n(2), as well as the very small α(2), indicate that these materials have large potential for all-optical switching applications in the near-infrared.
Highlights
The development of nonlinear (NL) photonic devices is motivating the discovery of new optical glasses useful for alloptical switching, optical limiting, lasers, and infrared technologies
Raincadtiohnighotfheorpmtaiclael xpfiabnesriso.n9,10coeAffimcoienngt that the phosphate glasses, those based on sodium-polyphosphate are frequently used as host matrices because of their high vitrifying ability and unusual capability to dissolve large amounts of other glass formers, modifiers, or intermediate compounds without reduction of glass forming ability.[11]
Several studies have shown that the physical properties and chemical durability of alkaliphosphate glasses can be improved by adding different metal oxides of high valence cations like Al3+, Bi3+, Pb2+, W6+, Mo6+, etc., as these elements form relatively stable metal−O−P crosslinked bonds.[12−14]
Summary
The development of nonlinear (NL) photonic devices is motivating the discovery of new optical glasses useful for alloptical switching, optical limiting, lasers, and infrared technologies. The choice of the appropriate material for all-optical switches is a challenge, because a high n2 value is often accompanied by a large two-photon absorption coefficient, α2 ∝ Imχ(3), leading to reduction of the device performance This behavior has motivated several groups to perform a characterization of different families of chalcogenide glasses owing to their large NL refractive index. NL optical absorption studies on NaPO3−BaF2−WO3 glass system, have shown that samples with more than 40% of WO3 molar content in the glass composition, have potential as optical limiters due to the high polarizability of tungsten oxide clusters the NL formed optical uppatroamtheitserWs.2O4 3 concentration, which increase binary compositions of tungsten-lead-pyrophosphate glasses (Pb2P2O7−WO3) were studied in the near-infrared region, and the results have shown that their NL response is faster than 100 fs and that an itnhceresaasmepolef sn.223occurs with the increasing of the WO3 amount in Bismuth-based glasses are promising materials since they present large NL properties.[26,27] Conventional network formers such as attract.
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