The underlying interest in metamaterials is the potential to have the ability to engineer the electromagnetic and optical properties of materials for a variety of applications. These include negative refractive index, magnetism at optical frequencies, subwavelength resolution, “backward” phase matching conditions for nonlinear optical processes, and even rendering objects invisible—cloaking. In recent years, it has been discovered that interactions between coherent light waves and thin-film surfaces can result in regulated energy exchange between incident and dispersed waves, opening up an array of new technological possibilities. Photonic planar metamaterials, composed of ultrathin media with nanoengineered optical characteristics, have the potential to reach the notion’s full potential for changing optical data processing paradigms, spectroscopy, and nonlinear optics.