[1] R. Zhou, B. Ibarra-Escamilla, J. W. Haus, P. E. Powers, Q. Zhan, Appl. Phys. Lett. 95, 191111 (2009).

[2] C. H. Yeh, and C. W. Chow, Laser Phys. Lett. 7, 158 (2010).

[3] H. Zhang, Q. Bao, D. Tang, L. Zhao, and K. Loh, Appl. Phys. Lett. 95, 141103 (2009).

[4] J. Zhang, D. Bauer, F. Konig, T. Dekorsy, X. Zhang, and Y. Chen, Chin. Opt. Lett. 8, 676 (2010).

[5] H. S. Kim, S. K. Kim, and B. Y. Kim, Opt. Lett. 21, 1144 (1996).

[6] I. A. Kostko and R. Kashyap, Opt. Express 14, 2706 (2006).

[7] N. J. C. Libatique, L. Wang, and R. K. Jain, Opt. Express 10, 1503 (2002).

[8] J. Qian, J. Su, X. Wang, and B. Zhu, Chin. Opt. Lett. 5, 229 (2007).

[9] T. Okoshi, K. Kikuchi, and A. Nakayma, Electron. Lett. 16, 630 (1980).

[10] L. E. Richter, H. I. Mandelberg, M. S. Kruger, and P. A. Mcgrath, IEEE J. Quantum Electron. 22, 2070 (1986).

[11] L. B. Mercer, J. Lightwave Technol. 9, 485 (1991).

[12] Y. Jia, P. Ou, Y. Yang, and C. Zhang, J. Beijing University of Aeronautics and Astronautics (in Chinese) 34, 568 (2008).

[13] M. Horowitz, R. Daisy, B. Fischer, and J. L. Zyskind, Opt. Lett. 19, 1406 (1994).

[14] Y. Cheng, J. T. Kringlebotn, W. H. Loh, R. I. Laming, and D. N. Payne, Opt. Lett. 20, 875 (1995).

[15] Z. Meng, G. Stewart, and G. Whitenett, IEEE J. Lightwave Technol. 24, 2179 (2006).