The depletion-layer width and the recorded electric field in thermally pole
d fused silica are investigated experimentally as a function of the applied
voltage. The depletion-layer width is observed to vary linearly with the p
oling voltage. The average electric field recorded in the depletion region
was found to be (5.3 +/- 0.3)x10(8) V/m for all samples, independently of t
he poling voltage. (C) 2000 American Institute of Physics. [S0003-6951(00)0
3218-6].