title: Coupled-mode equations for nonlinear directional couplers.
abstract: We point out some inconsistencies in the usual coupledmode formulation employed to model the nonlinear behavior of symmetric directional couplers. In particular, we show that special care is required when neglecting some of the nonlinear terms in the equations.
authors.forename: F J
authors.initials: FJ
authors.lastname: Fraile-Pelaez
authors.forename: G
authors.initials: G
authors.lastname: Assanto