A gradient-index lens for directing incident electromagnetic radiation comprises at least one substrate having a plurality of micro-features (e.g., trenches or holes) that may be arranged in a pattern of varied size and/or spacing. Each of the micro-features has at least one dimension that is less than a wavelength of the electromagnetic radiation. The spacing between adjacent micro-features is less than the wavelength of the electromagnetic radiation, and the size and spacing of the micro-features are sufficient to produce an effective refractive index profile of the lens that is graded.