A micro-electromechanical structure for modulating light beams includes multiple asymmetric deformable diffractive elements, each having an L-shaped cross section, split pedestal and flexible reflective member. The reflective member has an elongated shape, and a supported part and unsupported part. The split pedestal extends along the long dimension of the supported part of the reflective member and is anchored to a substrate which supports one or more electrodes or serves as an electrode. The diffractive element is movable between a non-energized position wherein the diffractive element acts to reflect a beam of light as a planar mirror, to an energized position wherein upon application of an electrostatic force, the diffractive element flexes independently about an axis parallel to the long dimension of each reflective member to vary a curvature of the reflective member to form a blazed grating.