[1] J. Limpert, S. Ho Fer, and A. Liem, Appl. Phys. B 75, 477 (2002).
[2] K. T. Vu, A. Malinowski, D. J. Richardson, F. Ghiringhelli, L. M. B. Hickey, and M. N. Zervas, Opt. Express 14, 10996 (2006).
[3] Y. Jeong, J. Sahu, D. Payne, and J. Nilsson, Opt. Express 12, 6088 (2004).
[4] M.-Y. Cheng, Y.-C. Chang, A. Galvanauskas, P. Mamidipudi, R. Changkakoti, and P. Gatchell, Opt. Lett. 30, 358 (2005).
[5] O. Schmidt, C. Wirth, I. Tsybin, T. Schreiber, R. Eberhardt, J. Limpert, and A. T¨unnermann, Opt. Lett. 34, 1567 (2009).
[6] H. Zhao, S. Zhou, C. Zhu, Y. Li, and J. Wu, Chinese J. Lasers (in Chinese) 33, 1359 (2006).
[7] Y. Duan, B. Huang, P. Zhang, R. Pan, and D. Ning, Chinese J. Lasers (in Chinese) 34, 1379 (2007).
[8] X. Zhao, B. Wu, Z. Yang, D. Zhou, J. Chen, Y. Xiao, C. Wang, and W. Du, Acta Opt. Sin. (in Chinese) 29, 2225 (2009).
[9] X. Liu, S. Du, Y. Xue, J. Zhou, B. He, Q. Lou, J. Dong, Y. Wei, D. Ning, and R. Pan, Chinese J. Lasers 36, 1877 (2006).
[10] F. Liu, L. Xu, W. Fan, B. Huang, M. Jiang, B. Liu, G. Kai, and S. Yuan, Acta Photo. Sin. 38, 3057 (2009).