The analogy of optical system to other physical systems has been attracting much attention over the past decades. In coupled optical lattices, phenomena originated from electronic systems, such as Bloch oscillations, Dynamic localization and Zener tunneling, have been extensively investigated and led to novel research directions and applications. Following this idea, harmonic oscillations are spatially mimicked by the propagation of supermodes in quadratically-coupled waveguide arrays. By analyzing the field envelope with the propagation constants and the superposition of the supermodes, we achieve conjugate-imaging at the half-period plane and self-imaging at the full-period plane, which give rise to the linear switching. Combining the linear switching and the nonlinear light propagation triggered at high power level, we demonstrate the superior performances of nonlinear power switching compared with traditional nonlinear directional couplers. Through the linear and nonlinear observation on AlGaAs waveguide array, we present the first experimental proof of the harmonic oscillations in optical waveguide arrays.

The analogy of optical system to other physical systems has been attracting much attention over the past decades. In coupled optical lattices, phenomena originated from electronic systems, such as Bloch oscillations, Dynamic localization and Zener tunneling, have been extensively investigated and led to novel research directions and applications. Following this idea, harmonic oscillations are spatially mimicked by the propagation of supermodes in quadratically-coupled waveguide arrays. By analyzing the field envelope with the propagation constants and the superposition of the supermodes, we achieve conjugate-imaging at the half-period plane and self-imaging at the full-period plane, which give rise to the linear switching. Combining the linear switching and the nonlinear light propagation triggered at high power level, we demonstrate the superior performances of nonlinear power switching compared with traditional nonlinear directional couplers. Through the linear and nonlinear observation on AlGaAs waveguide array, we present the first experimental proof of the harmonic oscillations in optical waveguide arrays.