| CPC G02B 1/005 (2013.01) | 16 Claims |
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1. An optical device comprising:
a substrate; and
a nanopattern layer on the substrate and configured to form a refractive index distribution to exhibit a certain phase delay profile with respect to light in a visible spectrum,
the nanopattern layer comprising a crystalline compound having a refractive index greater than 3 with reference to the light in the visible spectrum and having a height of 2 microns or less from a surface of the substrate,
wherein the nanopattern layer includes,
a high refractive index pattern comprising the crystalline compound; and
a low refractive index pattern comprising a material having a refractive index less than that of the crystalline compound,
wherein the low refractive index pattern comprises a plurality of nanopillars,
wherein the high refractive index pattern surrounds the plurality of nanopillars, and
wherein the high refractive index pattern comprises a selective epitaxial layer of the crystalline compound selectively around the plurality of nanopillars.
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