A device that provides light beam switching, agile steering of the light beam over a range of angles, and generation of arbitrary wavefront shapes with high spatial and temporal resolution. The agile device can include a volume diffractive structure comprising Bragg planes having one refractive index and the Bragg planes separated by regions containing an active optical medium. Electrodes (which may be the Bragg planes themselves, or may be arrayed adjacent to the active optical medium) are used to control the electric field intensity and direction across the structure, and thereby control the diffraction efficiency of the structure and the local phase delay imposed on a diffracted wavefront. Means are provided for addressing the many thousands of electrodes required for precise and rapid wavefront control. Applications include free-space atmospheric optical communications, near-eye displays, direct-view 3D displays, optical switching, and a host of other applications.