Atomic layer deposition process for fabricating dielectric metasurfaces for wavelengths in the visible spectrum
A method of fabricating a visible spectrum optical component includes: providing a substrate; forming a resist layer over a surface of the substrate; patterning the resist layer to form a patterned resist layer defining openings exposing portions of the surface of the substrate; performing deposition to form a dielectric film over the patterned resist layer and over the exposed portions of the surface of the substrate, wherein a top surface of the dielectric film is above a top surface of the patterned resist layer; removing a top portion of the dielectric film to expose the top surface of the patterned resist layer and top surfaces of dielectric units within the openings of the patterned resist layer; and removing the patterned resist layer to retain the dielectric units over the substrate.
1. A visible spectrum optical component, comprising:
a transparent substrate including a surface; and
dielectric units over the surface of the transparent substrate, wherein the dielectric units each comprises a top surface and sidewalls surrounding the top surface, and forms a discrete dielectric pillar,
wherein the dielectric units comprise:
a first dielectric unit having a width along a short axis and a height along a long axis that is greater than the width along the short axis, and
a second dielectric unit having a width along a short axis and a height along a long axis that is greater than the width along the short axis,
wherein the sidewalls directly contact air and have a surface roughness of no greater than 5 nm, and
wherein the width of the first dielectric unit is greater than the width of the second dielectric unit.
2. The optical component of claim 1 , wherein the width along the short axis is no greater than 200 nm, the height along the long axis is substantially perpendicular to the surface of the transparent substrate and is at least twice the width along the short axis.
3. The optical component of claim 1 , wherein a ratio of the height along the long axis to the width along the short axis is at least 5:1.
4. The optical component of claim 1 , wherein the sidewalls are substantially perpendicular to the surface of the transparent substrate.
5. The optical component of claim 1 , wherein the surface roughness of the sidewalls is no greater than 2 nm.
6. The optical component of claim 1 , wherein the dielectric units include a dielectric material that is amorphous or single-crystalline.
7. The optical component of claim 1 , wherein the dielectric units include a dielectric material having a light transmittance of at least 50% over the visible spectrum.
8. The optical component of claim 1 , wherein the dielectric units include a dielectric material having an imaginary part of a refractive index no greater than 0.1 over the visible spectrum, and a real part of the refraction index of at least 2 over the visible spectrum.
9. The optical component of claim 1 , wherein the optical component is configured to introduce a phase profile on incident light.
10. The optical component of claim 1 , wherein the optical component is a lens, a collimator, a polarizer, or a hologram.
11. The optical component of claim 1 , wherein the first dielectric unit of the dielectric units has a circular cross-section.
12. The optical component of claim 1 , wherein the height of the first dielectric unit and the second dielectric unit are substantially the same.
13. The optical component of claim 1 , wherein the dielectric units comprise repeating meta-gratings including the first dielectric unit and the second dielectric unit, and wherein the first dielectric unit of adjacent meta-gratings are separated by an identical meta-grating period.
14. The optical component of claim 1 , wherein the dielectric units comprise repeating meta-gratings including the first dielectric unit and the second dielectric unit.