[1] [1] R. Dorn, S. Quabis, and G. Leuchs, Phys. Rev. Lett. 91, 233901 (2003).

[2] [2] Q. Zhan, Adv. Opt. Photon. 1, 1 (2009).

[3] [3] X. Jia, Y. Wang, and B. Li, Opt. Express 18, 7064 (2010).

[4] [4] D. Deng, J. Opt. Soc. Am. B 23, 1228 (2006).

[5] [5] P. P. Banerjee, G. Cook, and D. R. Evans, J. Opt. Soc. Am. A 26, 1366 (2009).

[6] [6] D. Deng and Q. Guo, Opt. Lett. 32, 2711 (2007).

[7] [7] X. Jia, B. Li, and Y. Wang, Chin. Opt. Lett. 8, 517 (2010).

[8] [8] C. Maurer, A. Jesacher, S. Furhapter, S. Bernet, and M. Ritsch-Marte, New J. Phys. 9, 1 (2007).

[9] [9] A. Ito, Y. Kozawa, and S. Sato, J. Opt. Soc. Am. A 27, 2072 (2010).

[10] [10] K. Huang, P. Shi, G. W. Cao, Ke Li, X. B. Zhang, and Y. P. Li, Opt. Lett. 36, 888 (2011).

[11] [11] R. Martinez-Herrero, P. M. Mejias, S. Bosch, and A. Carnicer, J. Opt. Soc. Am. A 18, 1678 (2001).

[12] [12] H. Guo, J. Chen, and S. Zhuang, Opt. Express 14, 2095 (2006).

[13] [13] W. H. Carter, J. Opt. Soc. Am. 62, 1195 (1972).

[14] [14] G. Zhou, Opt. Lett. 31, 2616 (2006).

[15] [15] G. Wu, Q. Lou, and J. Zhou, Opt. Express 16, 6417 (2008).

[16] [16] X. Kang and B. L¨u, Opt. Commun. 262, 1 (2006).