[1] [1] Z. Jia, J. Yu, and G. K. Chang, IEEE Photon. Technol. Lett. 18, 1726 (2006).

[2] [2] J. Yu, G.-K. Chang, Z. Jia, A. Chowdhury, M.-F. Huang, H.-C. Chien, Y.-T. Hsueh, W. Jian, C. Liu, and Z. Dong, J. Lightwave Technol. 28, 2376 (2010).

[3] [3] Y. Shao, N. Chi, and J. Fan, IEEE Photon. Technol. Lett. 24, 1301 (2012).

[4] [4] A. Kanno, K. Inagaki, I. Morohashi, T. Kuri, I. Hosako, and T. Kawanishi, in Proceedings of IEEE Photon. Conf. (IPC11), Arlington, USA, TuJ4 (2011).

[5] [5] C. W. Chow, F. M. Kuo, J. W. Shi, C. H. Yeh, Y. F. Wu, C. H. Wang, Y. T. Li, and C. L. Pan, Opt. Express 18, 473 (2010).

[6] [6] A. Kanno, K. Inagaki, I. Morohashi, T. Sakamoto, T. Kuri, I. Hosako, T. Kawanishi, Y. Yoshida, and K. Kitayama, Opt. Express 19, B56 (2011).

[7] [7] L. Deng, M. Beltran, X. Pang, X. Zhang, V. Arlunno, Y. Zhao, A. Caballero, A. Dogadaev, X. Yu, R. Llorente, D. Liu, and I. Tafur Monroy, IEEE Photon. Technol. Lett. 24, 383 (2012).

[8] [8] D. Zibar, R. Sambaraju, A. Caballero, J. Herrera, U. Westergren, A. Walber, J. B. Jensen, J. Marti, and I. Tafur Monroy, IEEE Photon. Technol. Lett. 23, 810 (2011).

[9] [9] D. Zibar, R. Sambaraju, A. C. Jambrina, J. Herrera, and I. T. Monroy, in Proceedings of Opt. Fiber Conf., Los Angeles, USA, OThJ4 (2011).

[10] [10] X. Li, J. Yu, Z. Dong, Z. Cao, N. Chi, J. Zhang, Y. Shao, and L. Tao, Opt. Express 20, 24364 (2012).

[11] [11] J. Yu, Z. Jia, L. Yi, Y. Su, G. K. Chang, and T. Wang, IEEE Photon. Technol. Lett. 18, 265 (2012).