Coupled mode solutions of multiwaveguide systems

We present a new coupled mode formulation for guided wave propagation in an array of N -parallel waveguides and solve the resulting matrix differential equations. Analytic results for two- and three-waveguide systems are derived and several examples of three waveguide couplers are given. In particular, we show that field amplitudes in the case of asymmetrical excitation of a three-waveguide coupler are not periodic functions along the propagation direction as previously had been supposed.