[1] [1] W. J. Bock and T. R. Wolinski, Opt. Lett. 15, 1434 (1990).

[2] [2] T. A. Berkoff and A. D. Kersey, in Proceedings of 8th Optical Fiber Sensors Conf. 372 (1992).

[3] [3] K. A. Murphy, B. R. Fogg, and R. O. Claus, in Proceedings of 8th Optical Fiber Sensors Conf. 129 (1992).

[4] [4] J. O. Askautrud and H. E. Engan, in Proceedings of 8th Optical Fiber Sensors Conf. 101 (1992).

[5] [5] K. A. Murphy, M. S. Miller, A. M. Vengsarkar, and R. O. Claus, J. Lightwave Technol. 8, 1688 (1990).

[6] [6] A. Safaai-Jazi and J. C. McKeeman, J. Lightwave Technol. 9, 1047 (1991).

[7] [7] K. Bohnert, G. C. de Wit, and J. Nehring, J. Lightwave Technol. 13, 94 (1995).

[8] [8] B. D. Duncan, Modal interference techniques for strain detection in few-mode optical fibers M.S. Thesis, Bradley Dept. Elec. Eng., Virginia Polytechnic Institute and State University, Blacksburg (1988).

[9] [9] W. B. Spillman, B. R. Klin, L. B. Maurice, and P. L. Futhr, Appl. Opt. 28, 3166 (1989).

[10] [10] H. Wang and S. Zheng, Electrical Measurement and Intrumentation (in Chinese) 43, (5) 13 (2006).

[11] [11] Y. Liao, Fiber Optics (Tsinghua University Press, Beijing, 2000).