Ultraviolet laser pulses were found to introduce and destroy point defects that play a key role in the generation of second-order optical nonlinearities by thermal poling in high-purity silica glasses. The characteristics of the generation process depended largely on not only ≡Si—OH, O<sub>2</sub>, and H<sub>2</sub> content of the glasses but also the sequence of thermal poling and the pulse irradiation. There were two different kinds of nonlinearity: one localized in a thin layer near the sample surface (near-surface) and a bulk one spreading throughout the sample. The near-surface and bulk nonlinearities are associated with ≡Si—O<sup>−</sup> and ≡Si…Si≡, respectively.
© 2002 Optical Society of America
(160.6030) Materials : Silica
Akihiro Kameyama, Atsushi Yokotani, and Kou Kurosawa, "Generation and erasure of second-order optical nonlinearities in thermally poled silica glasses by control of point defects," J. Opt. Soc. Am. B 19, 2376-2383 (2002)