[1] J. Dai, N. Karpowicz, and X.-C. Zhang, Phys. Rev. Lett. 103, 023001 (2009).
[2] H. Wen and A. M. Lindenberg, Phys. Rev. Lett. 103, 023902 (2009).
[3] X. Xie, J. Dai, and X.-C. Zhang, Phys. Rev. Lett. 96, 075005 (2006).
[4] D. J. Cook and R. M. Hochstrasser, Opt. Lett. 25, 1210 (2000).
[5] K. Y. Kim, A. J. Taylor, J. H. Glownia, and G. Rodriguez, Nat. Photon. 2, 605 (2008).
[6] H. C. Wu, J. Meyer-ter-Vehn, and Z.-M. Sheng, New J. Phys. 10, 043001 (2008).
[7] A. A. Silaev and N. V. Vvedenskii, Phys. Rev. Lett. 102, 115005 (2009).
[8] N. Karpowicz and X.-C. Zhang, Phys. Rev. Lett. 102, 093001 (2009).
[9] D. Wang and J. Liu, Phys. Rev. A 86, 023833 (2012).