[1] H. Takara, T. Ohara, K. Mori, K. Sato, E. Yamada, Y. Inoue, T. Shibata, M. Abe, and K. Sat, Electron. Lett. 36, 2089 (2000).
[2] S. Demmler, J. Rothhardt, A. M. Heidt, A. Hartung, E. G. Rohwer, H. Bartelt, J. Limpert, and A. T¨unermann, Opt. Express 19, 20151 (2011).
[3] Th. Udem, R. Holzwarth, and T. W. H¨asch, Nature 416, 233 (2002).
[4] J. C. Travers, J. Optics 12, 1 (2010).
[5] J. J. Miret, E. Silvestre, and P. Andre, Opt. Express 17, 9197 (2009).
[6] G. M. Ponzo, X. Feng, P. Horak, F. Poletti, M. N. Petrovich, W. H. Loh, and D. Richardson, in Proceedings of 37th European Conference and Exposition on Optical Communications 10 (2011).
[7] C. Guo, S. Ruan, P. Yan, E. Pan, and H. Wei, Opt. Express 18, 11046 (2010).
[8] M. Delgado-Pinar, P. J. Mosley, J. C. Knight, T. A. Birks, and W. J. Wadsworth, in Proceedings of OSA/NP2010 NWD3 (2010).
[9] A. Kudlinski, A. K. George, J. C. Knight, J. C. Travers, A. B. Rulkov, S. V. Popov, and J. R. Taylor, Opt. Express 14, 5715 (2006).
[10] S. P. Stark, J. C. Travers, and P. S. J. Russell, Opt. Lett. 37, 770 (2012).
[11] J. M. Stone and J. C. Knight, Opt. Express 16, 2670 (2008).
[12] A. C. Judge, O. Bang, B. J. Eggleton, B. T. Kuhlmey, E. C. Magi, R. Pant, and C. M. de Sterke, in Proceedings of Frontiers in Optics FTuD4 (2009).