X-RAY-RADIATION EFFECTS ON 2ND-HARMONIC GENERATION IN THERMALLY POLEDSILICA GLASS

We observed a strong second-order optical nonlinearity in a fused sili ca glass poled under the condition of a static electric field of 4 kV/ mm at 260 degrees C. The nonlinearity layer was localized in the surfa ce region contacted on the positive electrode during poling in a thick ness comparable to or thinner than the interaction length of 22 mu m. The second-order nonlinearity was not observed in synthetic silica gla ss under the same poling condition. However, when the synthetic glass was first exposed to x-ray radiation, the poling induced a nonlinearit y 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. (C) 1997 Opti cal Society of America.