Various embodiments of the present invention are directed to optical devices comprising planar lenses. In one aspect, an optical device includes two or more planar lenses (208,209), and one or more dielectric layers (210-212). Each planar lens includes a non-periodic, sub-wavelength grating layer (1110), and each dielectric layer is disposed adjacent to at least one planar lens to form a solid structure. The two or more planar lenses are substantially parallel and arranged to have a common optical axis (214) so that light transmitted through the optical device substantially parallel to the optical axis is refracted by the two or more planar lenses.