Metasurfaces for redirecting light and methods for fabricating

A display system comprising:

• a waveguide;
• a light incoupling optical element disposed on a surface of the waveguide and configured to incouple light into the waveguide, the light incoupling optical element comprising:
• a multilevel metasurface comprising:
• a plurality of spaced apart protrusions having a pitch and formed of a first optically transmissive material;
• and
• a second optically transmissive material over and between the spaced apart protrusions,
• wherein the waveguide is one of a stack of waveguides, wherein each of the stack of waveguides comprises an associated multilevel metasurface,
• wherein the second optically transmissive material has a higher refractive index than either the first optically transmissive material or material forming the waveguide.

A display system comprising:

• a waveguide;
• a light incoupling optical element disposed on a surface of the waveguide and configured to incouple light into the waveguide, the light incoupling optical element comprising:
• a multilevel metasurface comprising:
• a plurality of spaced apart protrusions having a pitch and formed of a first optically transmissive material;
• and
• a second optically transmissive material over and between the spaced apart protrusions,
• wherein the waveguide is one of a stack of waveguides, wherein each of the stack of waveguides comprises an associated multilevel metasurface,
• wherein the second optically transmissive material has a higher refractive index than both the first optically transmissive material and the material forming the waveguide,
• wherein the first optically transmissive material has a lower refractive index than the material forming the waveguide.