[1] S. Montebugnoli, M. Boschi, F. Perini, P. Faccin, G Brunori, and E Pirazzini, Microw. Opt. Technol. Lett. 46, 48 (2005).

[2] J. F. Diehl, V. J. Urick, C. S. McDermitt, F. Bucholtz, P. S. Devgan, and K. J. Williams, IEEE Trans. Microw. Theory Technol. 60, 195 (2012).

[3] W. M. Dorsey, C. S. McDermitt, F. Bucholtz, and M. G. Parent, IEEE Trans. Antenn. Propag. 58, 5288 (2010).

[4] L. Liu, S. Zheng, X. Zhang, X. Jin, and H. Chi, J. Electromagn. Waves Appl. 24, 123 (2010).

[5] B. Wang, Z. Li, and X. Wang, Chin. Opt. Lett. 10, 071202 (2012).

[6] B. M. Haas and T. E. Murphy, IEEE Photon. Technol. Lett. 19, 729 (2007).

[7] S. Zou, Y. Wang, Y. Shao, J. Zhang, J. Yu, and N. Chi, Chin. Opt. Lett. 10, 070625 (2012).

[8] Y. Shi, L. Yan, and A. E. Willner, J. Lightwave Technol. 21, 2358 (2003).

[9] L.-S. Yan, A. E. Willner, and Y. Shi, IEEE Photon. Technol. Lett. 17, 1486 (2005).

[10] E. H. W. Chan and R. A. Minasian, J. Lightwave Technol. 26, 2882 (2008).

[11] S. Zhang, X. Zhang, and Y. Liu, Chin. Phys. Lett. 29, 084217 (2012).

[12] V. J. Urick, F. Bucholtz, J. D. McKinney, P. S. Devgan, A. L. Campillo, J. L. Dexter, and K. J. Williams, IEEE Trans. Microw. Theory Technol. 55, 1978 (2007).