Beam splitter and combiner based on Bloch oscillation in a spatially modulated waveguide array

We theoretically and numerically investigate light beam propagation in a periodic waveguide array that is spatially modulated with a certain structure which brings novel functionalities to the array. We find that a light beam may split, coalesce, deflect, and be localized during propagation in a simply modulated waveguide array. The phenomena described originate from the Bloch oscillation and supply a convenient method for fabricating on-chip beam splitters and beam combiners.