Generation and erasure of second-order optical nonlinearities in thermally poled silica glasses by control of point defects

This is the authors' abstract. We don't add key points for this paper.

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,O2, and H2 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- and ≡Si⋯Si≡, respectively.