[1] S.-B. Cho, J.-J. Lee, and I.-B. Kwon, Opt. Express 12, 4339 (2004).
[2] T. Schneider, M. Junker, and K.-U. Lauterbach, J. Opt. Soc. Am. B 23, 1012 (2006).
[3] A. Loayssa, D. Benito, and M. J. Garde, Opt. Lett. 25, 197 (2000).
[4] F. Zarinetchi, S. P. Smith, and S. Ezekiel, Opt. Lett. 16, 229 (1991).
[5] G. J. Cowle and D. Yu, Opt. Lett. 21, 1250 (1996).
[6] S. P. Smith, F. Zarinetchi, and S. Ezekiel, Opt. Lett. 16, 393 (1991).
[7] J. Geng, S. Stanes, M. Blake, and S. Jiang, Appl. Opt. 46, 5928 (2007).
[8] J. Geng, S. Staines, and S. Jiang, Opt. Lett. 33, 16 (2008).
[9] W. Guan and J. R. Marciante, IEEE J. Quantum Elec- tron. 46, 674 (2010).
[10] G. J. Cowle, D. Yu, and Y. T. Chieng, J. Lightwave Technol. 15, 1198 (1991).
[11] M. H. Al-Mansoori and M. A. Mahdi, Opt. Express 11, 7649 (2008).
[12] W. Guan and J. R. Marciante, Opt. Lett. 15, 3131 (2009).