Photonic structures, devices, and methods

A method for making a photonic periodic structure, the method comprising the steps of:

• a) providing a substrate;
• b) depositing at least one planar layer comprising two or more sublayers having different sublayer refractive indices;
• c) depositing a chemical-mechanical-polishing (CMP) stop layer;
• d) depositing a resist layer;
• e) patterning the resist layer by nano-imprint lithography to impress recesses into the resist layer in accordance with a desired periodicity;
• f) directionally etching to remove resist from the recesses in the resist layer, whereby first openings are formed in the resist layer;
• g) depositing a hard mask material over the resist layer and into the first openings;
• h) removing the resist, while leaving a periodic pattern of hard mask material only where previously deposited in the first openings;
• i) selectively etching through the at least one planar layer in accordance with the periodic pattern of hard mask material to form second openings, whereby the photonic periodic structure is formed.