|Budget Amount *help
¥8,100,000 (Direct Cost: ¥8,100,000)
Fiscal Year 2002: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2001: ¥7,200,000 (Direct Cost: ¥7,200,000)
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.