[1] Y. Li, F. Ma, N. Dai, G. Yang, and P. Lu, Chinese J. Lasers (in Chinese) 34, 1009 (2007).

[2] L. Yuan, Y. Zhao, H. He, and J. Shao, Chin. Opt. Lett. 5, S257 (2007).

[3] Y. Cui, H. Yu, Y. Zhao, Y. Jin, H. He, and J. Shao, Chin. Opt. Lett. 5, 680 (2007).

[4] J. G. Fujimoto, J. M. liu, and E. P. Ippen, Phys. Rev. Lett. 53, 1837 (1984).

[5] B. Rethfeld, Phys. Rev. Lett. 92, 187401 (2004).

[6] M. Lenzner, J. Krüger, S. Sartania, Z. Cheng, Ch. Speilmann, G. Mourou, W. Kautek, and F. Krausz, Phys. Rev. Lett. 80, 4076 (1998).

[7] A. Kaiser, B. Rethfeld, M. Vicanek, and G. Simon, Phys. Rev. B 61, 11437 (2000).

[8] H. Sun, T. Jia, C. Li, X. Li, S. Xu, D. Feng, X. Wang, X. Ge, and Z. Xu, Solid State Commun. 141, 127 (2007).

[9] S. Xu, T. Jia, X. Li, D. Feng, H. Sun, C. Li, X. Wang, H. Kuroda, R. Li, and Z. Xu, Jpn. J. Appl. Phys. 44, 8201 (2005).

[10] B. C. Stuart, M. D. Feit, A. M. Rubenchik, B. W. Shore, and M. D. Perry, Phys. Rev. Lett. 74, 2248 (1995).

[11] N. Bloembergen, IEEE J. Quantum Electron. 10, 375 (1974).

[12] D. Du, X. Liu, G. Korn, J. Squier, and G. Mourou, Appl. Phys. Lett. 64, 3071 (1994).

[13] Z. Xia, J. Shao, and Z. Fan, Chinese J. Mater. Res. (in Chinese) 20, 581 (2006).