PREPARATION OF MICRO-OPTICS MATERIALS BY MEANS OF SURFACE CRYSTALLIZATION OF GLASSES

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The purpose of the research project is to develop a new technique, Ultrasonic Surface Treatment (UST), control the surface crystallization of glasses for preparation functional optical materials, especially for nonlinear materials. The potential applications in micro-optical devices are to be explored. The research results obtained are summarized as follows :Surface crystallization of LiNbOィイD23ィエD2 on KィイD22ィエD2O・(35-x)LiィイD22ィエD2O・30NbィイD22ィエD2OィイD25ィエD2・35SiOィイD22ィエD2 (mol%) glasses was investigated. The c-axis orientation of surface crystallized LiNbOィイD23ィエD2 was improved when 10mol% KィイD22ィエD2O was added in the glass. Furthermore, Li ions in the LiNbOィイD23ィエD2 crystallites were partially exchanged by K ions from the glass. Transparent surface crystallized LiNbOィイD23ィエD2 films on glasses were prepared by the controlled heat treatment, which showed optical second harmonic generation. The estimated second-order nonlinear optical susceptibilities were dィイD233ィエD2=6.40pm/V and dィイD231 … More ィエD2=dィイD221ィエD2=dィイD224ィエD2=dィイD215ィエD2=1/3dィイD233ィエD2=2.14pm/V for a thin film (1.33mm in thickness) prepared after heating at 620℃ for 3h, when the c-axis oriented thin film was described by a space group CィイD2αVィエD2.Crystal slab optical waveguides of calcium aluminum silicate (CaィイD22ィエD2AlィイD22ィエD2SiOィイD27ィエD2) were prepared by controlled surface crystallization of glass using ultrasonic surface treatment (UST) and heat treatment. Here UST is necessary to get uniform crystalline films showing optical waveguide characteristics. By controlling the depth of the waveguides with varying heat treatment temperatures and tomes, single-mode and multi-mode waveguides were obtained. The refractive index and optical propagation loss of the slab waveguides was characterized.The research results indicate that the UST technique for controlled surface crystallization of glass is very unique and useful. By means of this technique, oriented, dense, and transparent thin films showing optical nonlinear and waveguide could be prepared. The advantages of glass and crystal could be combined by preparing surface crystallized optical materials. There is potential application of the technique for various micro-optical materials.Particularly, the UST technique reduces significantly the beginning temperature of crystallization, avoiding deformation of mother glass. It is therefore concluded that the UST technique has a bright prospect of developing the optical waveguides. Less