[1] F. Dong and F. Da, Opt. Lett. 37, 3561 (2012).
[2] C. Wang and F. Da, Opt. Express 20, 18459 (2012).
[3] S. Li, X. Su, W. Chen, and L. Xiang, J. Opt. Soc. Am. A 26, 1195 (2009).
[4] X. Zhou, T. Yang, H. Zhou and H. Zhao, Opt. Lett. 37, 1904 (2012).
[5] M. Wielgus and K. Patorski, Appl. Opt. 50, 5513 (2011).
[6] X. Zhou, H. Zhao, and T. Jiang, Opt. Lett. 34, 2033 (2009).
[7] Y. Zhou and H. Li, Opt. Express 19, 18207 (2011).
[8] J. S. Smith, J. R. Soc. Interface 2, 443 (2005).
[9] G. Rilling and P. Flandrin, IEEE Trans. Signal Process 56, 85 (2008).