Researchers from The Weizmann Institute of Science in Rehovot, Israel, and the University of Glasgow in the UK reported in the Aug. 28 issue of Physical Review Letters that they have developed a technique to engineer the diffraction properties of waveguide arrays. The ability to control diffraction, they suggest, may lead to low-power all-optical soliton switches. The group produced 5- and 6-mm-long AlGaAs waveguide arrays with a zigzag pattern. A synchronously pumped optical parametric oscillator tuned to 1.53 µm served as the input. The arrays displayed reduced, canceled and reversed diffraction in accordance with coupled-mode theory.