[OPTICAL REVIEW Vol. 8, No. 3 (2001) 159-162]
Threshold Conditions for Bulk Second-Order Nonlinearity and Near-Surface Second-Order Nonlinearity in Thermally Poled Infrasil Silica
Mingxin QIU1,*, Toru MIZUNAMI1, Teruo SHIMOMURA1 and Michitaka OHTAKI2
1Department of Electrical Engineering, Faculty of Engineering, Kyushu Institute of Technology, 1-1, Sensuicho, Tobata, Kitakyushu, 804-8550 Japan, 2Department of Molecular and Material Sciences, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University 6-1, Kasuga-koen, Kasuga, 816-8580 Japan
(Received September 13, 2000; Accepted March 26, 2001)
Generation of bulk second-order nonlinearity in silica glass requires higher poling temperature or longer poling time than that of near-surface second-order nonlinearity. The threshold conditions for initiating the bulk second-order nonlinearity are studied on Infrasil fused silica glass. The threshold poling time is strongly dependent on the poling temperature. The near-surface second-order nonlinearity is also studied, especially the dependence of thickness of the nonlinear layer on the poling temperature, poling voltage and poling time. Secondary-ion mass-spectroscopy measurement showed depletion of Na+ ions at the anodic surface. We assume there is an ionic wave during poling traveling from the anodic surface to generate the dipolar electric field that induces the near-surface second-order nonlinearity.
Key words : nonlinear optics, second-harmonic generation, optical glass, ion conduction in glass, amorphous physics, solid surface