Optical second-order nonlinearity of transparent glass-ceramics containing BaTiO_3 precipitated via surface crystallization

摘要

Second-harmonic generation of transparent glass-ceramics containing BaTiO_3 crystalline phase was investigated using Maker fringe method. When 15BaO.15TiO_2.70TeO_2 glass was heat-treated at 415 deg. C for 0.5-12 h. (101)- or (110)-oriented BaTiO_3, crystals precipitated in the near-surface region. The resultant glass-ceramics exhibit second-harmonic generation. Variation of second-harmonic intensity with ang1e of incidence, i.e., the Maker fringe pattern changes drastically with an increase in heat treatment time and temperature. No second-harmonic signal was detected in glass-ceramics derived from l5SrO. l5TiO_2 70TeO_2 glass. These facts suggest that BaTiO_3, crystal is responsible for the second-order nonlinear phenomenon, although its structure is closer to cubic than tetragonal according to x-ray diffraction measurements. In order to estimate second-order nonlinear optical coeffcient d~(2), Maker fringe patterns of the BaTiO_3-containing glass-ceramics were analyzed. For the glass-ceramic after heat treatment for 0.5 h, d_33 and thickness of BaTiO_3-crystallized layer, L, are 3.65 pm/V and 3.43 pm, respectively. The value of second-order nonlinear optica1 coefficient is comparable to those of BaTiO_3 films prepared via metalorganic chemical vapor deposition and pulsed-laser deposition. On the other hand, the glass-ceramic heat-treated for l2 h exhibits d_15 = 0.3l pm/V and L = 300 mu m. The thickness of the layer active in second-order nonlinearity evaluated from the Maker fringe pattern is coincident with the observation by scanning electron microscopy.