[1] L. Tong, F. Zi, X. Guo, and J. Lou, Opt. Commun. 285, 4641 (2012).

[2] G. Brambilla, F. Xu, P. Horak, and Y. Jung, Advances in Optics and Photonics 1, 107 (2009).

[3] G. Brambilla, Opt. Lett. 12, 043001 (2010).

[4] G. Brambilla, Opt. Fiber Technol. 16, 331 (2010).

[5] L. Tong, F. Zi, X. Guo, and J. Lou, Opt. Commun. 285, 4641 (2012).

[6] J. Fu, X. Yin, N. Li, and L. Tong, Chin. Opt. Lett. 6, 112 (2008).

[7] F. Tian, G. Yang, J. Bai, Q. Zhou, C. Hou, J. Xu, and Y. Liang, Chin. Opt. Lett. 8, 326 (2010).

[8] X. Kou, G. Vienne, and G. Wang, Chin. Opt. Lett. 8, 560 (2010).

[9] Z. Wei, Z. Song, X. Zhang, and Z. Meng, Chin. Opt. Lett. 11, 1671 (2013).

[10] J. Jakle and K. Kawasaki, J. Phys. Condensed Matter 7, 4351 (1995).

[11] M. Sumetsky, Y. Dulashko, J. M. Fini, A. Hale, and J. W. Nicholson, Opt. Lett. 31, 2393 (2006).

[12] M. Sumetsky, Opt. Express 15, 1480 (2007).

[13] G. Zhai and L. Tong, Opt. Express 15, 13805 (2007).

[14] A. V. Kovalenko, V. N. Kurashov, and V. Kisil, Opt. Express 16, 5797 (2008).

[15] L. Tong and M. Sumetsky, Subwavelength and Nanometer Diameter Optical Fibers (Springer, 2009).

[16] G. Brambilla, F. Xu, and X. Feng, Electron. Lett. 42, 517 (2006).

[17] S. Sakaguchi, J. Lightwave Technol. 11, 187 (1993).

[18] X. Zhang, Z. Meng, Z. Hu, H. Yang, Z. Song, and Y. Hu, Proc. SPIE 7278, 72781N (2008).