[1] K. Tanizawa, T. Kurosu, and S. Namiki, in Proceedings of OFC 2010 OThJ4 (2010).
[2] R. Ludwig, B. Huettl, H. Hu, C. Schmidt-Langhorst, and C. Schubert, in Proceedings of OFC 2008 OWJ6 (2008).
[3] W. Xu, G. Duan, G. Fang, L. Xi, and X. Zhang, Acta Opt. Sin. (in Chinese) 28, 226 (2008).
[4] H. Wernz, S. Herbst, S. Bayer, H. Griesser, E. Martins, C. F¨urst, B. Koch, V. Mirvoda, R. Noe, A. Ehrhardt, L. Sch¨urer, S. Vorbeck, M. Schneiders, D. Breuer, and R.-P. Braun, in Proceedings ECOC 2009 3.4.3 (2009).
[5] B. Koch, R. No′e, D. Sandel, V. Mirvoda, V. Filsinger, and K. Puntsri, in Proceedings of OFC 2010 OThD4 (2010).
[6] J. He, L. Liu, L. Chen, and S. Wen, Chinese J. Lasers (in Chinese) 35, 1185 (2008).
[7] C. Yu, Z. Pan, T. Luo, S. Kumar, L.-S. Yan, B. Zhang, L. Zhang, Y. Wang, M. Adler, and A. E. Willner, in Proceedings of OFC 2005 OThR5 (2005).
[8] Z. Pan, S. Chandel, and C. Yu, in Proceedings of CLEO/QELS 2006 CFP2 (2006).
[9] C. Yu, Y. Wang, Z. Pan, T. Luo, S. Kumar, B. Zhang, and A. E. Willner, Opt. Lett. 34, 1657 (2009).
[10] X. Wu, L. Christen, J.-Y. Yang, S. R. Nuccio, A. Willner, and L. Paraschis, in Proceedings of LEOS 2007 ThX3 (2007).
[11] G.-W. Lu and T. Miyazaki, IEICE Electron. Express 5, 1 (2008).
[12] X. Tian, Y. Su, W. Hu, L. Leng, and H. J. Thiele, in Proceedings of ECOC 2006 84 (2006).
[13] H. Toda, J. Miyashita, A. Chiba, T. Sakamoto, T. Kawanishi, M. Tsuchiya, and M. Izutsu, in Proceedings of LEOS 2008 WB2 (2008).