[1] N. Park, J. W. Dawson, K. J. Vahala, and C. Miller, Appl. Phys. Lett. 59, 2369 (1991).

[2] A. Gloag, N. Langford, K. McCallion, and W. Johnstone, J. Opt. Soc. Am. B 13, 921 (1996).

[3] C. R. Giles, Lightwave Technol. 15, 1391 (1997).

[4] R. Slavik, S. Doucet, and S. LaRochelle, Lightwave Technol. 21, 1059 (2003).

[5] R. Gafsi, Opt. Fiber Technol. 6, 299 (2000).

[6] K. O. Hill and G. Meltz, Lightwave Technol. 15, 1263 (1997).

[7] K. O. Hill, B. Malo, F. Bilodeau, D. C. Johnson, and J. Albert, Appl. Phys. Lett. 62, 1035 (1993).

[8] S. V. Chernikov, J. R. Taylor, and R. Kashyap, Opt. Lett. 18, 2023 (1993).

[9] J. Hubner, P. Varming, and M. Kristensen, Electron. Lett. 33, 139 (1997).

[10] M. Ibsen, A. Shaif-ul, M. N. Zervas, A. B. Grudinin, and D. N. Payne, Photon. Technol. Lett. IEEE 11, 1114 (1999).

[11] S. Yamashita and G. J. Cowle, Lightwave Technol. J. 17, 509 (1999).

[12] M. Ibsen, E. Ronnekleiv, G. J. Cowle, M. N. Zervas, and R. I. Laming, Electron. Lett. 36, 143 (2000).

[13] S. Jie, D. Yitang, C. Xiangfei, Z. Yejin, and X. Shizhong, Photon. Technol. Lett. IEEE 18, 2587 (2006).