Large second-harmonic generation of thermally poled sodium borophosphate glasses

Second harmonic generation (SHG) has been obtained in a rich in sodium niobium orophosphate glass by a thermal poling treatment. The thermally poled glass SHG signal has been studied through an original analysis of both transmitted and reflected polarized Maker-fringe patterns. Therefore, the second order nonlinear optical (NLO) efficiency was estimated from the simulation of the Maker-fringe patterns with a stepwise decreasing profile from the anode surface. A reproducible χ(2) susceptibility value as high as 5.0 ±0.3 pm/V was achieved at the anode side..

Large second-harmonic generation of thermally poled sodium borophosphate glasses

Second harmonic generation (SHG) has been obtained in a rich in sodium niobium orophosphate glass by a thermal poling treatment. The thermally poled glass SHG signal has been studied through an original analysis of both transmitted and reflected polarized Maker-fringe patterns. Therefore, the second order nonlinear optical (NLO) efficiency was estimated from the simulation of the Maker-fringe patterns with a stepwise decreasing profile from the anode surface. A reproducible χ(2) susceptibility value as high as 5.0 ±0.3 pm/V was achieved at the anode side..

Crystallization and second harmonic generation in thermally poled niobium borophosphate glasses

Crystallization of glasses with compositions (1−x)(0.95 NaPO3+0.05 Na2B4O7)+xNb2O5, x=0.4, 0.43, 0.45, 0.48 was investigated by differential scanning calorimetry and X-ray powder diffraction. Crystallization of two phases was observed in the glasses with x=0.43–0.48. First phase is a sodium niobate with the structure of tetragonal tungsten bronze (Tc~720-760°C) and second phase is Na4Nb8P4O32 (Tc~830-850°C). The crystallization of sodium niobate is correlated with increasing of nonlinear optical efficiency reported for thermally poled glasses with x>0.4..

Correlation of large SHG responses with structural characterization in borophosphate niobium glasses

Transparent and homogeneous sodium borophosphate niobium glasses with good optical quality were obtained for Nb2O5 proportion up to 50 mol%. Large NLO second-order susceptibilities, up to not, vert, similar5 pm/V for the highest niobium loading, are generated through an efficient thermal poling process which induces a strong space-charge migration of Na+ cations..

Effect of sodium to barium substitution on the space charge implementation in thermally poled glasses for nonlinear optical applications

Thermally poled niobium borophosphate glasses in the system 0.55(0.95−y) NaPO3+y/2 Ba(PO3)2+0.05Na2B4O7)+0.45Nb2O5 were investigated for second order optical nonlinear (SON) properties. Bulk glasses were studied by Raman spectroscopy, thermal analysis, optical and dielectric measurements. The sodium to barium substitution does not lead to significant changes in optical properties, crystallization of glasses and coordination environment of polarizable niobium atoms. However, the ionic conductivity decreases drastically with the increase of barium concentration. Secondary ion mass spectroscopy has been used to determine the element distribution in the anode layer of the thermally poled glasses. The second order optical susceptibilities gradually decrease from χ(2)=2.8 pm/V to zero with the increase of barium content. Using a simple electrical model, variations of nonlinear optical responses have been correlated with dielectric characteristics

Multimodal structural characterization of Ge−S−I glasses by combination of DFT calculation and IR and polarized Raman Spectroscopy

From a dual experimental−theoretical vibrational analysis, we propose a new rationalized structural description of Ge−S−I chalcogenides glasses at the nanoscale. A vibrational multipolar approach based on a simultaneous deconvolution of infrared (IR) and polarized Raman spectra (RSVV and RS-HV) has been applied on these glasses. According to recent results on the amorphous GeS2 structure by X-Ray and neutron diffraction and to our spectral analyses, we suggest that the local structure of the glass backbone is effectively described by a combination of α-GeS2 nanolayers, edge-sharing GeS4 tetrahedra (ES-Td, ca ~50%), and cornersharing GeS4 tetrahedra (CS-Td, ca ~50%). We have then compared the experimental spectra to the calculated IR and polarized Raman spectra of some selected GexSyIz structural units obtained by density functional theory calculation. The stretching modes of the Ge−S−I occurring in the high frequency spectral range (300−450 cm−1) are essentially those of the GeS2 glass backbone and have been revisited. In addition, through a careful analysis of the vibrational multipolar activities of stoichiometric and over-stoichiometric sulfur glasses between 180 and 280 cm−1, we propose new assignments for the seven modes that have been identified by our trimodal spectral analysis. We finally suggest that there is a competition between the insertion of atomic iodine as a glass modifier which involves the Ge−S−I clusters and molecular diiodine as a spectator encaged between two α-GeS2 nanolayers

Correlation Between Physical, Optical And Structural Properties Of Sulfide Glasses In The System Ge-Sb-S

Germanium-based sulfide glasses in the Ge-Sb-S system have been elaborated and studied. A relationship between the structure, the composition and the linear optical properties of the glass has been established. The effects of the introduction of Sb on the structure using IR and Raman spectroscopies and on the linear refractive index have been discussed. We have shown that the progressive introduction of Sb2S3 in the glass system (1 - x)GeS2-xSb2S3 (with x = 0.10, 0.20, 0.40, 0. 62 and 0.80) decreases the number of GeS4 units in the glass network. As results, the glass transition temperature, the Vicker\u27s microhardness and the stability of the glass against crystallization decrease dramatically. An increase in the density and the linear refractive index as well as shift of the absorption bandgap to infrared have also been observed. Similar behavior has been observed for the glasses of composition Ge0.23Sb yS0.77-y with an increase of y, except in the material\u27s Vicker\u27s microhardness, which increases with an increasing Sb content. This latter result indicates that the microhardness also depends on Sb 2S3 content but seems to be more sensitive to GeS 2 content variation. © 2005 Elsevier B.V. All rights reserved

Second-harmonic generation of thermally poled silver doped sodo-borophosphate glasses

Sodium niobium borophosphate glass, with a composition of 0.58(0.95NaPO3+0.05Na2B4O7)+0.42Nb2O5, has been doped with monovalent silver ions. Second harmonic generation (SHG) has been obtained from the poling treatment of this sample. The second order nonlinearity from the anode side was estimated from an analysis of transmitted polarized Maker-fringe patterns. Thanks to the original Maker fringe simulations, a value of 3 pm/V is obtained with the silver doped glass that unambiguously scales an enhancement of ~35% with respect to the nondoped glass susceptibility. For both glasses, the nonlinear layer is found to be sodium-depleted up to 4  µm inside the anode, in accordance with quantitative energy dispersive x-ray spectroscopy characterizations. This comparative study indicates complex space-charge-migration processes during the poling treatment. The relative enhancement of the SHG signal of the silver doped glass is correlated with the increase in its linear susceptibility

Micro-structuring the surface reactivity of a borosilicate glass via thermal poling

Thermal poling was proven successful to induce second order nonlinear properties and concurrent modification of composition, structure and chemical reactivity in glasses. With current efforts to reduce devices sizes in components employing such attributes, means to control changes at the micrometer scale are needed. We present a micro-imprinting poling process to locally tailor surface properties of a glass. Measurements using infrared, Raman and second harmonic generation microscopies confirm that changes in glass structure associated with an induced static electric field are responsible for the enhanced surface reactivity that is successfully controlled at the micrometer scale.Initiative d'excellence de l'Université de Bordeau