Based on the solution of a simplified canonical problem, the possible margin of error on the predicted coupling length according to the coupled-mode theory as applied to fiber and integrated optical guides is inferred. It was found that coupling length obtained according to the coupled-mode theory is usually accurate to within 20% of the actual value provided that the frequency of operation is above the cutoff frequency of the antisymmetric mode of the coupled structure.
© 1978 Optical Society of America
C. Yeh, F. Manshadi, K. F. Casey, and A. Johnston, "Accuracy of directional coupler theory in fiber or integrated optics applications," J. Opt. Soc. Am. 68, 1079-1083 (1978)