X-ray radiation effects on second-harmonic generation in thermally poled silica glass

Abstract

We observed a strong second-order optical nonlinearity in a fused silica glass poled under the condition of a static electric field of 4 kV/mm at 260 °C. The nonlinearity layer was localized in the surface region contacted on the positive electrode during poling in a thickness comparable to or thinner than the interaction length of 22 µm. The second-order nonlinearity was not observed in synthetic silica glass under the same poling condition. However, when the synthetic glass was first exposed to x-ray radiation, the poling induced a nonlinearity of almost the same value as that in the fused silica glass, which we attribute to the x-ray formation of defects. The values were found to depend on water contents in the synthetic silica glass.