[1] [1] R. W. Boyd, Nonlinear Optics (Elsevier Science, 2003).

[2] [2] A. R. Davoyan, I. V. Shadrivov, and Y. S. Kivshar, Opt. Express 16, 21209 (2008).

[3] [3] A. R. Davoyan, I. V. Shadrivov, and Y. S. Kivshar, Opt. Express 17, 4833 (2009).

[4] [4] M. L. Brongersma and V. M. Shalaev, Science 328, 440 (2010).

[5] [5] A. Degiron and D. R. Smith, Phys. Rev. A 82, 033812 (2010).

[6] [6] D. Dai and S. He, Opt. Express 18, 17958 (2010).

[7] [7] F. F. Lu, T. Li, X. P. Hu, Q. Q. Cheng, S. N. Zhu, and Y. Y. Zhu, Opt. Lett. 36, 3371 (2011).

[8] [8] F. F. Lu, T. Li, J. Xu, Z. D. Xie, L. Li, S. N. Zhu, and Y. Y. Zhu, Opt. Express 19, 2858 (2011).

[9] [9] Z. Ruan, G. Veronis, K. L. Vodopyanov, M. M. Fejer, and S. Fan, Opt. Express 17, 13502 (2009).

[10] [10] Z. J. Wu, X. K. Hu, Z. Y. Yu, W. Hu, F. Xu, and Y. Q. Lu, Phys. Rev. B 82, 155107 (2010).

[11] [11] H. Ishikawa, Appl. Phys. Express 2, 042202 (2009).

[12] [12] A. R. Davoyan, I. V. Shadrivov, and Y. S. Kivshar, Opt. Express 17, 20063 (2009).

[13] [13] A. R. Davoyan, I. V. Ahadrivov, A. A. Zharov, D. K. Gramotnev, and Yu. S. Kivshar, Phys. Rev. Lett. 105, 116804 (2010).

[14] [14] I. D. Rukhlenko, A. Pannipitiya, and M. Premaratne, Opt. Lett. 36, 3374 (2011).

[15] [15] X. T. Kong, W. G. Yan, Z. B. Li, and J. G. Tian, Opt. Express 20, 12133 (2012).

[16] [16] R. F. Oulton, V. J. Sorger, D. A. Genov, D. F. P. Pile, and X. Zhang, Nature Photon. 2, 496 (2008).

[17] [17] T. Holmgaard and S. I. Bozhevolnyi, Phys. Rev. B 75, 245405 (2007).