Air-gap encapsulation of nanostructured optical devices

An optical device comprising:

• a plurality of optical device structures distributed along a surface of a substrate, wherein each structure of the plurality of optical device structures comprises:
• a critical dimension less than 2 microns corresponding to a width or a diameter of a cross section of each structure;
• and
• a structure material having an optical device refractive index between about 1.7 and about 4.0;
• and
• a support layer in contact with the surface of the substrate, wherein the support layer surrounds each optical device structure of the plurality of optical device structures along the surface of the substrate, the support layer comprising:
• a support material having a support layer refractive index of about 1.0 to about 1.5;
• and
• a plurality of openings that extend through the support layer to the surface of the substrate, wherein each of the plurality of openings has a refractive index of about 1.0;
• wherein a height of the support layer is greater than a height of the plurality of optical device structures, and
• wherein the support layer is only disposed between the plurality of optical device structures.