Thermal poling of thin silica glass films: Design rules for optical fibers and waveguides (original) (raw)
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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.
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.
Characterization of thermal poling in silica glasses by current measurements
Journal of Non-Crystalline Solids, 2003
We present herein a charge migration model that predicts the electric field distribution within a Suprasile silica planar sample after poling. The predicted distribution is in agreement with the currents measured at the electrodes during the poling and depoling processes. This electric field is responsible for an apparent second-order non-linear coefficient originating from the third-order one. Numerical values obtained from fits of the experimental curves with the model equations are compatible with the values obtained by optical characterization reported in the literature.
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.
Dynamics of the second-order nonlinearity in thermally poled silica glass
Applied Physics Letters, 2001
We study the temporal evolution of both the second-order nonlinear coefficient and of the nonlinear thickness in thermally poled silica-glass slides by using a high-resolution all-optical technique. A time delay in the nonlinearity formation is observed, followed by an increase to a maximum, and a final decrease. The thickness is shown to increase at a rate that differs significantly from that reported for the corresponding ionic charge fronts. Our measurements also show strong dependencies on sample thickness and these can be attributed to different electric fields in the depletion region.
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.
Mechanism for thermal poling in twin-hole silicate fibers
Journal of the Optical Society of America B, 2002
Thermal poling and depoling current for twin-hole fibers was measured. The current's evolution was compared with electro-optic evolution. The thermally stimulated discharge efficiency was measured to be 5%. Atomic-force microscopy was used to study the HF-etched transverse sections of thermally poled twin-hole fiber. Thermal poling modified the etch rate in two rings about the anode hole. The outer ring was found to move with time, whereas the inner ring's position was stationary. Results are explained by use of a spacecharge model that comprises two components: movement of impurity ions and charge injection in which the charge injection component dominates the poling characteristics.
Measurement and calculation of electrostrictive effects in a twin-hole silica glass fiber
Journal of the Optical Society of America B, 2000
A precise method for evaluating the electro-optic coefficients of an optical fiber is introduced. The method was used to characterize the third-order nonlinearity of twin-hole silica fibers. The polarization dependence expected for isotropic materials and the Kleinmann symmetry condition was not observed. We explain the lack of polarization dependence of the third-order tensor by taking into account the electrostrictive contribution to the quadratic electro-optic effect.
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.
IEEE Photonics Technology Letters, 2000
Thermally poled fused silica glass was characterized with second-harmonic optical and scanning electron microscopy. It was found that, along with the creation of a second-order nonlinearity (SON) layer under the anode surface, a layer of nanometersized crystalline particles exists near the anode surface. Its spatial distribution, as well as the average crystal size, was measured and compared with that of the induced SON.