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- Pernice, P., et al.
(author)
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Electric field induced structural modification and second order optical nonlinearity in potassium niobium silicate glass
- 2009
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In: Journal of Non-Crystalline Solids. - : Elsevier BV. - 0022-3093 .- 1873-4812. ; 355:52-54, s. 2578-2582
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Journal article (peer-reviewed)abstract
- Second harmonic generation properties have been studied in 23 K2O center dot 27Nb(2)O(5) center dot 50 SiO2 glass subjected to thermal poling. The poling-induced optical nonlinearity. with chi((2)) = 3.8 pm/V, has been related to structural modifications within a surface layer of a few microns on the anode side, as evidenced by means of confocal micro-Raman mapping along the sample thickness. The data indicate that the structural changes result from a charge transport process that causes network modifications in an alkali depleted layer whose thickness is comparable with that of the non-linear region. The Raman data also indicate that in the alkali depleted layer the network polymerization degree increases as a consequence of ion migration. The origin of the nonlinearity and the mechanisms activated by poling are discussed. The mechanism of non-bridging-oxygen to bridging-oxygen bond switching is proposed to explain ion migration and the subsequent structural changes in the glass.
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