We etched thermally poled fused-silica coverslips in 49% HF for 30 s transverse to the poling direction to reveal structural details of the nonlinear region. A peaked ridge below the anode surface, corresponding to a slower etch rate than that of the bulk SiO<sub>2</sub> , was located ~5μm below the anode surface for a poling time of 30 s. The ridge moved deeper into the glass logarithmically with poling time. This trend is qualitatively consistent with a recent model for the formation of the space-charge region that includes injection of hydrogen ions at the anode surface.
© 1998 Optical Society of America
(160.2750) Materials : Glass and other amorphous materials
(190.0190) Nonlinear optics : Nonlinear optics
(190.4160) Nonlinear optics : Multiharmonic generation
(190.4370) Nonlinear optics : Nonlinear optics, fibers
(190.4400) Nonlinear optics : Nonlinear optics, materials
Thomas G. Alley and S. R. J. Brueck, "Visualization of the nonlinear optical space-charge region of bulk thermally poled fused-silica glass," Opt. Lett. 23, 1170-1172 (1998)