Improved nonlinear coefficient (0.7 pm/V) in silica thermally poled at high voltage and temperature

Abstract

It is shown that in thermally poled silica a substantially increased second-order nonlinearity is induced when both the poling voltage and the temperature are increased under standard poling conditions (/spl sim/275/spl deg/C//spl sim/5 kV). Increases in the voltage result in a nonlinear region with a greater width and buried depth, while increases in the temperature enhance the peak nonlinear coefficient d/sub 33/. In a silica sample poled at 400/spl deg/C and 20 kV, a nonlinear region 10 /spl mu/m deep was measured with a d/sub 33/ of 0.7 pm/V which is twice as large as that for a sample poled under standard conditions, and the highest reliable reported value.