A spatial light modulator pixel comprises a movable reflective surface in which an array of subapertures is formed, wherein each subaperture contains a fixed (non-movable) island reflector. The movable reflector is micromechanically actuated so that the combination of movable and fixed reflectors functions alternately as a plane mirror or as a two-dimensional diffraction grating (i.e., a “bigrating”), depending on the movable reflector's position. The device is useful for applications such as maskless lithography and high-resolution printing.