Three-Dimensional Microscopic Crystallization in Photosensitive Glass by Femtosecond Laser Pulses at Nonresonant Wavelength

We investigated three-dimensional microscopic crystallization by irradiation of femtosecond and nanosecond laser pulses at a nonresonant wavelength of 630 nm in a photosensitive glass containing Ag+ and Ce3+. The pulse widths of the lasers were 150 fs and 3 ns, respectively. By focusing the femtosecond laser beam and following heat-treatment, spot crystallization within the glass of about 10 ?m successfully occurred without surface crystallization, while the use of the nanosecond laser beam produced no crystallization. By using the femtosecond laser, it is possible to create three-dimensional structured crystallization because of the use of transparent light and the presence of a threshold for crystallization.