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Structural Control of Ceramics with a Femtosecond Pulse Laser

用飞秒脉冲激光控制陶瓷的结构

基本信息

批准号：
13450356
负责人：
HIRAO Kazuyuki
金额：
$ 5.18万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

In this research, we carried out the basic research aiming at the internal modification of glasses and the development of three-dimensional optical circuit through nonlinear optical effect such as multiphoton process induced by femtosecond laser. In particular, we performed the experiments on making useful glasses with the function of wavelength conversion. The main results of this research are as follows. When Li_2O-Nb_2O_5-SiO_2 glass system were irradiated with femtosecond laser with a repetition frequency of 200kH (800nm), the refractive-index was changed at the focal point and then some precipitations appeared within the glass, as the irradiation time became long. In contrast, when they were irradiated with femtosecond laser with a repetition frequency of 1 kHz, only cracks were formed in spite of the irradiation time longer than 1h. X-ray diffraction pattern indicate that the precipitated compounds are nonlinear optical crystal, LiNbO_3. Also, blue emission was observed immediately after the precipitation of the crystal. It was confirmed that the emission was centered at 400nm, corresponding to half the wavelength of incident light. As a result, we have found that the irradiation with femtosecond laser makes possible the precipitation of LiNbO_3 crystals with large nonlinear optical coefficient. The overall results demonstrate the possibility or space-selective precipitation of nonlinear optical crystals using ultra-fast pulsed laser, and it is expected that the precipitation of oriented crystals and the formation of waveguides find their application to wavelength-conversion devise.

本研究通过飞秒激光诱导的多光子过程等非线性光学效应，针对玻璃的内部改性和三维光路的开发开展了基础研究。特别是，我们进行了制作具有波长转换功能的有用玻璃的实验。本研究的主要结果如下。当重复频率为200kH（800nm）的飞秒激光照射Li_2O-Nb_2O_5-SiO_2玻璃体系时，随着照射时间的延长，焦点处的折射率发生变化，玻璃内部出现一些沉淀。相反，当用重复频率为1kHz的飞秒激光照射它们时，尽管照射时间长于1小时，但仅形成裂纹。 X射线衍射图谱表明析出的化合物为非线性光学晶体LiNbO_3。另外，在结晶析出后立即观察到蓝色发光。经证实，发射中心位于 400nm，相当于入射光波长的一半。结果发现，飞秒激光照射可以析出具有大非线性光学系数的LiNbO_3晶体。总体结果证明了使用超快脉冲激光进行非线性光学晶体空间选择性沉淀的可能性，并且预计取向晶体的沉淀和波导的形成在波长转换器件中得到应用。