Negative refraction in optical waveguide arrays with loss layers

Light propagation in waveguide arrays exhibits many intriguing phenomena (e.g., anomalous diffraction and refraction), which have attracted a great deal of research interest in the past decade. Much of the beam dynamics in waveguide arrays can be explained by employing the diffraction relationship as well as bandgap structures. Since Bloch modes in waveguide arrays can be somewhat explained by using the superposition of the guiding modes of a single waveguide, one may wonder if it is possible to control the beam propagation in waveguide arrays by use of waveguide mode-selection technique. This paper proposes a novel mode-selection technique for optical waveguides by introducing losses into the waveguide structure, and demonstrate for the first time negative refraction of a single Gaussian beam in such waveguide arrays due to suppression of the even guiding modes.