Electric field induced structural modification and second order optical nonlinearity in potassium niobium silicate glass (original) (raw)
Related papers
Physical Review A, 2002
The creation of a second-order nonlinear susceptibility (2) in thermally poled silica glasses is known to be related to positive charge migration. As opposed to currently used models, we herein propose a model that takes into account charge dissociation and charge recombination occurring during the poling process. This model, known as the Proctor and Sutton model, was used to determine the space-charge distribution within silica plates submitted to an electric field. In this paper, we perform theoretical calculations in order to adapt this model to the high values of the applied electric field during the poling process. Moreover, we prove that there is a voltage threshold below which no (2) can be induced. We also point out the existence of a nonzero electric field within the entire sample. To test the validity of this model, we poled 1 mm thick Infrasil™ silica slabs using voltages ranging from 0 to 4 kV. Maker fringe patterns have been recorded in order to estimate the magnitude of the induced nonlinear (2) coefficient. We report experimental evidence of a poling voltage threshold of 900 V in these samples.
Influence of different poling methods on the second-order nonlinearity in fused silica glasses
Optics Communications, 2000
Fused silica glass samples poled by different methods showed large differences in their second-order optical nonlinearities. Large second-harmonic signals were obtained only when a depletion layer was formed near the anode surface. By comparing the influences of plate poling and corona poling, the necessary conditions to form a depletion layer in fused silica glass are discussed.
Optical Materials, 2003
It is shown that magnitudes of the Kerr coefficient and permittivity of 19Na 2 O-11K 2 O-2B 2 O 3 -2CdO-(66 À x)SiO 2 -xNb 2 O 5 glasses, where 0 < x < 37, correlate with the content of the Na 2 O Á Nb 2 O 5 groupings, with that content being estimated by Raman scattering data. This allows assigning to these groupings, or to other structural entities containing such groupings (for example, crystal motifs), the responsibility for high-polarizability and Kerr sensitivity of the glasses. .ru (A.A. Lipovskii). 0925-3467/03/$ -see front matter Ó 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 5 -3 4 6 7 ( 0 2 ) 0 0 0 9 3 -9
Bulk and near-surface second-order nonlinearities generated in a BK7 soft glass by thermal poling
Journal of the Optical Society of America B, 2002
Bulk second-order nonlinearity was generated in BK7 glass at a higher temperature and with a longer poling time than near-surface second-order nonlinearity. The temporal decay of the bulk second-order nonlinearity was slower than that of the near-surface second-order nonlinearity. The thickness of the near-surface nonlinear layer increased with poling time. Poled BK7 glass was also measured by x-ray photoelectron spectroscopy. Depletion of Na at the anodic surface and its accumulation at the cathodic surface was observed. At the cathodic surface, a higher-energy peak near O (1s) appeared, which shows peroxy-radical defects. At the anodic surface, a lower-energy peak near Si (2p) appeared, which may be attributed to EЈ centers or to twocoordinated Si defects. The mechanisms of generation of these defects and of the second-order nonlinearities are discussed.
Journal of Non-Crystalline Solids, 2010
Efficient thermal poling of electronically conducting glass is prevented by the inherent difficulty to record a large electrostatic field within such glasses. To overcome this limitation, a waveguide/substrate configuration has been proposed, in which the glass for poling was deposited as a film of appropriate thickness on a substrate chosen for its higher ionic conductivity. Owing to this configuration, the poling voltage drops entirely across the glass film, allowing high electrostatic field to be recorded in spite of the high electronic conductivity of the glass. The proposed method was demonstrated here in the case of bismuth-zinc-borate glasses, which possess high potential for poling because of their high intrinsic χ (3). A four-fold enhancement of χ (2) compared to bulk glass, from ~0.5 to ~2 pm/V, is demonstrated. It is also shown that the χ (2) values obtained are the highest sustainable by the glass limited by the onset of nonlinear conductivity. The waveguide/substrate configuration intrinsically allows obtaining perfect overlap of the poling induced secondorder nonlinearity with the guiding region of the waveguide. An equivalent RC-circuit model describing the poled glass reveals that the value of the poling-induced second-order nonlinearity is strongly dependent on the ratio β between ionic and electronic conductivity. The most promising glass systems for poling are found to be the ones displaying the highest product χ (3) β. This work is performed on bismuth-zinc-borate heavy metal oxide glasses but the waveguide/substrate configuration proposed here is likely to be equally successful in enhancing the second-order nonlinearity in high χ (3) electronic conducting glasses such as for example telluride and chalcogenide glasses.
Journal of the Optical Society of America B, 2006
Soda-lime silicate (SLS) glasses were thermally poled at 230°C -280°C with dc voltages up to 2 kV applied to induce a second-order optical nonlinearity. Accompanying structural modifications to the thermally poled SLS glasses were investigated with scanning electron microscopy. On the cathode surface, sodium metasilicate crystals were formed through the reduction of migrating sodium ions at the cathode. At the anode, intense phase separation occurred within several micrometers beneath the anode surface during the thermal poling process. These structural modifications are attributed to the electric field enhancement effect. The second-order nonlinearity induced in such poled samples was found to still be present after a long period of high-temperature annealing, perhaps mainly due to a hindering effect from the phase separation and/or accumulated calcium ions to the recombination of space charges.
Emergence of Structural Anisotropy in Optical Glasses Treated to Support Second Harmonic Generation
Physical Review Letters, 1998
Structural alterations in v-SiO2 induced by "thermal poling", a treatment which makes the glass able to double the frequency of an impinging infrared light, are revealed by neutron diffraction as a breakdown of the macroscopic isotropy. This leads to concomitant changes in the vibrational density of states measured by inelastic neutron scattering. The observations are found to be consistent with the emergence of partial ordering within the glassy matrix along the direction of an electrostatic field applied during the poling treatment. 42.70.Ce, 42.65.Ky
2010
This paper describes progress in characterizing the distribution and localization of the second-order nonlinearity induced in thermally poled silicate glasses and optical waveguides, in particular, optical fibers. It starts by describing the basics of the poling technique, especially the most commonly used "thermal poling" technique. Then results of systematic investigation of the distribution of the second-order nonlinearity in poled glass and special fibers using second-harmonic microscopy are presented. Interesting issues such as the effectiveness of the poling technique for waveguides formed by ultrafast laser pulses are also discussed.
Journal of Applied Physics, 2008
Monovalent silver ions, resulting from a thin silver layer initially deposited at the anode surface, have been introduced using the field-assisted ion-exchange technique in sodium niobium borophosphate glasses. A reproducible susceptibility ͑2͒ could be gained after this poling treatment, although a drop in the nonlinearity is observed due to the introduction of silver ions. From energy dispersive x-ray spectroscopy, it has been found that the nonlinear layer is characterized by a strong migration of sodium ions 4 m deep inside the anode side, which have been partially replaced by silver ions. These results indicate a complex space-charge-migration process during the poling treatment, which is involved in the decrease in the mean second-harmonic generation signal.
Effect of minority species on thermal poling of used silica glasses
High second-order nonlinearity (SON) in poled silica glasses [l] is of great interest for the development of linear electro-optic modulators and frequency converters monolithically integrated into optical fibres or planar glass waveguides. However, its origin [ 1,2] is not fully understood. The extrinsic effects of poling time and voltage on second-harmonic (SH) generation in thermally-poled silica glass have been studied [ 1,3]. In particular the quadratic dependence of the maximum SH signal on the applied voltage indicated linear dependence of the SON on internal electric field [3]. There are several studies on intrinsic effects associated with defects [ 1, 41 and minority species such as OH [ 1,5] and Na [ 1,6] in thermal poling of silica glasses. In this work we carried out a systematic analysis of oxygen related defects and impurities (OH and Na) in commercial fused silica glasses (without relying on their catalogue data) and discuss their effects on SON.