[1] [1] J. Armstrong J. Lightwave Technol. 27, 189 (2009).

[2] [2] E. Ip and J. M. Kahn, J. Lightwave Technol. 26, 3416 (2008).

[3] [3] L. Du and A. Lowery, in Proceedings of OFC 2009 OTuO1 (2009).

[4] [4] L. Li, Y. Qiao, and Y. Ji, Chin. Opt. Lett. 9, 060604 (2011).

[5] [5] Y. Ji, D. Ren, H. Li, X. Liu, and Z. Wang, Sci. China F 54, 215 (2011).

[6] [6] Y. Hao, Y. Li, R. Wang, and W. Huang, Chin. Opt. Lett. 10, 010701 (2012).

[7] [7] G. J. Foschini, Bell Laboratories Technical Journal 1, 41 (1996).

[8] [8] I. B. Djordjevic, L. Xu, and T. Wang, Opt. Express 16, 14845 (2008).

[9] [9] X. Liu and F. Buchali, in Proceedings of ECOC 08 Mo.3.E.2 (2008).

[10] [10] X. Liu and F. Buchali, Opt. Express 16, 21944 (2008).

[11] [11] S. L. Jansen, I. Morita, T. C. Schenk, and H. Tanaka, J. Opt. Netw. 7, 173 (2008).

[12] [12] Y. Qiao, Z. Wang, and Y. Ji, Chin. Opt. Lett. 8, 888 (2010).

[13] [13] X. Yi, W. Shieh, and Y. Tang, IEEE Photon. Technol. Lett. 19, 919 (2007).

[14] [14] W. Shieh, IEEE Photon. Technol. Lett. 20, 605 (2008).

[15] [15] W. Shieh, R. S. Tucker,W. Chen, X. Yi, and G. Pendock, Opt. Express 15, 350 (2007).

[16] [16] X. Liu, F. Buchali, and R. W. Tkach, J. Lightwave Technol. 27, 3632 (2009).

[17] [17] H. Bao and W. Shieh, Opt. Express 15, 4410 (2007).