Optical elements based on polymeric structures incorporating inorganic materials

A method of fabricating an optical element, comprising:

• providing a substrate having a first refractive index, the substrate being transparent in the visible spectrum;
• forming, on the substrate, periodically repeating polymer structures having an initial refractive index;
• performing a first atomic layer deposition step to form a molecular layer of a first precursor on the periodically repeating polymer structures;
• performing a second atomic layer deposition step using a second precursor, which is different from the first precursor, to form a layer of target material on the periodically repeating polymer structures, wherein the periodically repeating polymer structures comprising the layer of target material are configured to diffract visible light and have a second refractive index greater than the first refractive index and greater than the initial refractive index,
• wherein performing the first atomic layer deposition step occurs in a reaction chamber, and wherein the method comprises purging, subsequent to performing the first atomic layer deposition step, the reaction chamber of the first precursor,
• wherein performing the second atomic layer deposition step occurs in the reaction chamber, and wherein the method comprises purging, subsequent to performing the second atomic layer deposition step, the reaction chamber of the second precursor, and
• wherein performing the first atomic layer deposition step, purging of the first precursor, performing the second atomic layer deposition step, and purging of the second precursor constitute a growth cycle, and the method comprises repeatedly performing the growth cycle until a predetermined thickness of the layer of target material is achieved;
• and
• controlling, during the growth cycle, a purge time, a total pressure, a partial pressure, and/or a substrate temperature to control diffusion of the first precursor and the second precursor into the periodically repeating polymer structures.