[1] O. Frazao, P. Caldas, F. M. Araujo, L. A. Ferreira, and J. L. Santos, Opt. Lett. 32, 1974 (2007).
[2] Y. Liu and L. Wei, Appl. Opt. 46, 2516 (2007).
[3] F. Pang, W. Liang, W. Xiang, N. Chen, X. Zeng, Z. Chen, and T. Wang, IEEE Photon. Technol. Lett. 21, 76 (2009).
[4] T. Zhao, Y. Gong, Y. Rao, Y. Wu, Z. Ran, and H. Wu, Chin. Opt. Lett. 9, 050602 (2011).
[5] C.-Y. Lin, L. A. Wang, and G.-W. Chern, J. Lightwave Technol. 19, 1159 (2001).
[6] Y. Lin, J. A. R. Williams, and I. Bennion, IEEE Photon. Technol. Lett. 12, 531 (2000).
[7] J. H. Lim, H. S. Jang, K. S. Lee, J. C. Kim, and B. H. Lee, Opt. Lett. 29, 346 (2004).
[8] L. V. Nguyen, D. Hwang, S. Moon, D. S. Moon, and Y. Chung, Opt. Express 16, 11369 (2008).
[9] B. Dong, D.-P. Zhou, L. Wei, W.-K. Liu, and J. W. Y. Lit, Opt Express 16, 19291 (2008).
[10] H. Y. Choi, M. J. Kim, and B. H. Lee, Opt. Express 15, 5711 (2007).
[11] B. Dong, D.-P. Zhou, and L. Wei, J. Lightwave Technol. 28, 1011 (2010).
[12] Z. Tian, S. S.-H. Yam, J. Barnes, W. Bock, P. Greig, J. M. Fraser, H.-P. Loock, and R. D. Oleschuk, IEEE Photon. Technol. Lett. 20, 626 (2008).
[13] P. Lu, L. Men, K. Sooley, and Q. Chen, Appl. Phys. Lett. 94, 131110 (2009).
[14] Z. Tian and S. S.-H. Yam, IEEE Photon. Technol. Lett. 21, 161 (2009).
[15] P. Lu, L. Men, K. Sooley, and Q. Chen, Appl. Phys. Lett. 94, 131110 (2009).
[16] M. Deng, C.-P. Tang, T. Zhu, and Y.-J. Rao, Opt. Commun. 284, 2849 (2011).
