The problem of achieving high second-order nonlinearities in glasses: The role of electronic conductivity in poling of high index glasses

Abstract

a b s t r a c tEfficient 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 second-order 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-zincborate 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.

Depletion Layer Formation in Alkali Silicate Glasses by Electro-Thermal Poling

“…3,[15][16][17] The extent of electro-thermal poling has been shown to be dependent on both ionic and electronic conductivities. 4 The dielectric response of the depletion layer and bulk glass during poling also remains unclear, as we note that the dielectric constant of alkali silicate glasses increases with increasing alkali content. …”

“…Electro-thermal poling was primarily developed to induce secondorder nonlinear (SONL) optical susceptibility in glasses by application of DC electric fields. [1][2][3][4] In recent years, interest in this technique has expanded beyond SONL to enhance a variety of biological, physical and chemical properties of glass.5-18 For example, electro-thermal poling has been reported to modify a glass' affinity to atmospheric water at the anode region.18 Electro-thermal poling generally comprises of four main processing steps. First, a glass is heated to a predetermined poling temperature (T p ) below the glass transition temperature (T g ), which allows for increased ionic conductivity while retaining the preformed dimensions.…”

“…Electro-thermal poling was primarily developed to induce secondorder nonlinear (SONL) optical susceptibility in glasses by application of DC electric fields. [1][2][3][4] In recent years, interest in this technique has expanded beyond SONL to enhance a variety of biological, physical and chemical properties of glass.…”

Thermal Poling of Optical Glasses: Mechanisms and Second‐Order Optical Properties

“…As most of the poling treatments reported in literature were carried out in air, one cannot under estimate the respective influence of the compensation mechanisms detailed in a previous section of this manuscript. Finally, if the glass electronic conductivity is no more negligible during the poling treatment, it could prevent high fields to be recorded in the glass. Such a behavior has been clearly shown in bismuth‐zinc‐borate‐poled glasses in which it exists a well‐known polaronic conduction whereby electron can hope between the two valence states of bismuth . Then, if electronic conduction is certainly negligible in silicate‐ or phosphate‐based glasses, one cannot avoid to take into account this negative charge motion mechanism in some of the high‐χ (3) glass families such as tellurites or chalcogenides.…”

Advances and Prospects of Frequency Doublers Based On Periodically Poled Silica Fibres

“…However, this does not necessarily correspond to the highest field strength that silica glass can withstand. In the bismuth zinc borate ternary glass system we tested three films of different thickness deposited on borosilicate substrate [5]. The I-V curves reveal the existence of the onset of a nonohmic current initiating, for all film thicknesses, at field strengths of 2.87  0.26 × 10 8 V/m corresponding to  (2) = 1.41  0.12 pm/V in reasonable agreement with  (2) = 1.20  0.04 obtained from maker fringe measurements (Fig.1c).…”