The femtosecond laser induced void array inside Al<sub>2</sub>O<sub>3</sub> crystals was discussed. The void array was formed spontaneously under the irradiation of a single beam of infrared femtosecond laser which was focused at a fixed point inside the Al<sub>2</sub>O<sub>3</sub> crystal sample. It was found that the regular voids only could be fabricated near the sample surface, which was different from the situation in CaF<sub>2</sub> single crystal reported before. The possible mechanism of the phenomena was also discussed.
© 2008 Chinese Optics Letters
Xiao Hu, Juan Song, Qinling Zhou, Luyun Yang, Xiaodan Wang, Congshan Zhu, and Jianrong Qiu, "Self-formation of void array in Al2O3 crystal by femtosecond laser irradiation," Chin. Opt. Lett. 6, 388-390 (2008)