Suppression of sidelobes in the far-field radiation patterns of optical waveguide arrays

Arrays of coherent optical emitters are attractive for high-speed, wide-angle optical beamsteering or deflection, but uniform arrays radiate undesirable sidelobes. It is shown that dramatic suppression of sidelobes can be accomplished by configuring emitters in a nonuniform pattern. A nearly optimum radiation pattern for scanning results from gradually doubling the interelement spacing across a one-dimensional array. As an example, a 100-element waveguide array of minimum interelement spacing 5 μm radiates a 0.08° main lobe (full width at half-maximum) with a 30× suppression of sidelobe intensity.