Analysis of a directional coupler by use of rigorous coupled-mode theory is presented. The coupling process is explained by the mutual coupling of modes of a single waveguide that is due to the presence of the other waveguide. It is explicitly shown by example that the radiation modes that take part in the coupling are just those needed to form the guided modes of the composite double-guide structure.
© 1994 Optical Society of America
Original Manuscript: May 11, 1994
Published: October 15, 1994
Jiří Čtyroký and Lars Thylén, "Analysis of a directional coupler by coupled modes of a single waveguide," Opt. Lett. 19, 1621-1623 (1994)