Conservative coupling between modes of propagation—A tabular summary

There are four distinct ways in which two modes of propagation can be coupled conservatively, i.e., coupled so that the mode amplitudes satisfy either a power conservation law or a Manley-Rowe relation. The type of coupling that results in any particular case depends upon the relative parities of the modes, the relative directions of the group velocities and, in the case of parametric coupling, the relative signs of the frequencies of the two modes. Each of these four types of coupling results in a distinct and characteristic type of behavior. This paper presents a set of tables that summarize the principal characteristics of the four types for both direct and parametric coupling.