Large second-harmonic generation of thermally poled sodium borophosphate glasses

Second harmonic generation ( SHG) has been obtained in a rich in sodium niobium borophosphate glass by a thermal poling treatment. The thermally poled glass SHG signal has been studied through an original analysis of both transmitted and reflected polarized Maker- fringe patterns. Therefore, the second order nonlinear optical ( NLO) efficiency was estimated from the simulation of the Maker-fringe patterns with a stepwise decreasing profile from the anode surface. A reproducible chi((2)) susceptibility value as high as 5.0 +/- 0.3 pm/ V was achieved at the anode side. The nonlinear layer, found to be sodium- depleted up to 5 mu m deep inside the anode side, identical to the simulated nonlinear zone thickness, indicates a complex space-charge-migration/ nonlinear glass matrix response process. (C) 2005 Optical Society of America.