Thermal poling of silica in air and under vacuum: The influence of charge transport on second harmonic generation

Abstract

A comparison between thermal poling of silica in air and in vacuum is reported. It is shown that the second-order susceptibility and thickness of the nonlinear layer as well as their time evolution are highly dependent on the surrounding poling atmosphere. In the vacuum case a charge distribution (under the anode) more complex and broader than that for the air case has also been revealed by laser induced pressure pulse measurements. A multiple charge carrier model can explain the formation and evolution of the depletion region under the anode. The findings are relevant to achieve improved nonlinearities in fiber and waveguide devices.

Investigation of bioglass–electrode interfaces after thermal poling

“…6 we can exclude the following charge compensation mechanisms: (a) accumulation of Ca 2+ ions, (b) accumulation of Pt n+ ions after oxidation of Pt, and (c) depletion of negatively charged O n− ions. A charge compensation mechanisms that was discussed in the literature for the anodic depletion layer of poled optical glasses is the field-induced injection of protons [17,18]. The protons may originate from moisture in the sample environment that diffuses through the electrode.…”

Depletion region in thermally poled fused silica

“…The location, spatial extent, charge composition, and electric-field profile in the depletion layer depend on the poling voltage, temperature, atmosphere, and poling time. [2][3][4][5] Some of the studies revealed that this region is a few micrometers wide 1,[4][5][6][7][8] and that the width is larger for vacuum poling than for poling in air. 5 Further, in some cases the depletion region was found to be neutral, and to finish at a thin distribution of negative charge.…”

“…[2][3][4][5] Some of the studies revealed that this region is a few micrometers wide 1,[4][5][6][7][8] and that the width is larger for vacuum poling than for poling in air. 5 Further, in some cases the depletion region was found to be neutral, and to finish at a thin distribution of negative charge. 5,6 Positive ion in-diffusion 3,7 and negative-charge emission [3][4][5]9,10 have been invoked to explain the neutrality of the layer.…”

Second harmonic generation induced by poling in borophosphate bulk and thin film glasses

“…Models have attributed the secondorder optical non-linearity to the correlation of the third-order susceptibility and the E dc field in the depletion zone [7]. The creation of a depletion zone near the anodic face with a few microns depth has been experimentally proved mainly in silica glass by LIPP (laser induced pressure probe) measurements but also in more exotic oxide glasses by XPS measurements [8][9][10]]. An expanded model including ion-exchange between a high mobility ion and a much lower mobility ion (related to H + ) driven by the high electric field has also been reported [11].…”