Photonic crystal structures are made by a method including steps of providing a substrate, depositing at least one planar layer to form a stack, each planar layer of the stack comprising two or more sublayers having different sublayer refractive indices, depositing a hard mask material, depositing an imprintable material over the hard mask material, patterning the imprintable material by imprinting an array of depressions, and directionally etching at the depressions a regular array of openings through the hard mask material and the stack.