Tailoring modal power distribution in common-core waveguide arrays

In this paper, the scattering matrix method (SMM) is used to analyze the modal properties of evanescently coupled waveguide arrays with cores spaced equidistant from a common central core. Propagation constants and field distributions of the fundamental in-phase supermodes are obtained for waveguide arrays comprising three, four, five, six, and seven cores. The authors show how the coupling strength among individual cores can be controlled by adjusting the properties of the central core, thereby providing a means of tailoring the near-field mode profile. By properly selecting the parameters of the central core, the authors also show how an equal power distribution among all cores can be achieved. A seven-core waveguide array is discussed in detail including the effects of varying core spacing and central core parameters on the supermodes and dispersion properties of the array.