[3] Falcial R, Scheggi A M, Schena A. Approximate calculation method for predicting selective properties of fused monomode biconical couplers. Interna. J. Optoelectron., 1990, 5(1):41～46
[4] Snyder A W. Coupled mode theory for optical fiber. J. Opt. Soc. Am., 1972, 62(6):1267～1277
[5] Mortimore D B. Theory and fabrication of 4×4 single-mode fused optical fiber couplers. Appl. Opt., 1990, 29(3):371～374
[6] Haus H A, Molter-Ore L. Coupled multiple waveguide systems. J. Quant. Electron., 1983, QE-19(5):840～844
[7] Chuang Shun-lien. A coupled mode theory for multiwaveguide systems satisfying the reciprocity theorem and power conservation. J. Lightwave Technol., 1987, 5(1):174～183
[8] She Shouxian, Qiao Li. Analysis of three channel waveguide directional couplers by a variational method and weighted residual method. Opt. Commun., 1988, 87(4):271～276
[9] Kubo H, Yasumoto K. Numerical analysis of three-parallel embedded optical waveguides. J. Lightwave Technol., 1989, 7(12):1924～1931
[10] Paney F P, Hussey C D, Yataki M S. Modeling fused single mode fiber couplers. Electron. Lett., 1985, 21(4):461～462
[11] Chen Y. Asymmetric triple-core couplers. Opt. and Quant. Electron., 1991, 24(4):539～553
[12] Naoto Kishi, Eikichi Yamashita, Hirokazu Kawabta. Modal and coupling field analysis of optical fibers with linearly distribution multiple cores. J. Lightwave Technol., 1989, 7(6):902～907
[13] Ankiewicz A, Synder A W, Zheng X H. Coupling between parallel optical fiber cores-critical examination. J. Lightwave Technol., 1986, 4:1317～1323
[14] Hardy A, Streifer W. Coupled mode solutions of multi-waveguide systems. IEEE J. Quant. Electron., 1986, QE-22(4):528～534
[15] Hardy A, Streifer W, Osinski M. Weak coupling of parallel waveguides. Opt. Lett., 1988, 13(2):161～163
[16] Sun Liping, Ye Peida. General analysis of 3×3 optical fiber directional couplers. Microwave and Optical Technol. Lett., 1989, 2(2):52～54
[17] Chew Y H, et al.. Performance of single- and Double-ring resonators using 3×3 optical fiber coupler. J. Lightwave Technol., 1993, 11(12):1998～2008
[18] Vance R W C, Love J D. Design procedures for passive planar coupled waveguide devices. IEE Proc. Optoelectron., 1994, 141(4):231～241
[20] Gradsheyn I S, Ryshik I M. Table of Integrals. Series and Products, New York: Academic Press, 1990. 29
