Ultra-flat optical device with high transmission efficiency
An optical device includes a nanostructured transparent dielectric film, which is a Huygens metasurface. The Huygens metasurface imparts a phase change to light propagating through or reflecting from the surface. The phase change can be achieved by means of a resonant interaction between light and the Huygens resonators, resulting in a controllable phase change of 0 to 2π with approximately 100% light transmission characterized by a below 0.1 dielectric loss tangent of delta and with the height of the resonators less than the wavelength of light. In one embodiment, the metasurface includes titanium dioxide, but many materials or stacks of different materials may be used. The optical device is functional throughout the visible spectrum between 380 and 700 nm. The nanostructured transparent dielectric film includes a plurality of Huygens resonators. The phase and the amplitude of the nanostructured transparent dielectric film are modulated by arranging the plurality of Huygens resonators such that certain properties, including the radius and height of each Huygens resonator, as well as the gap between two adjacent Huygens resonators, are controlled to optimize the performance of the optical device within the visible spectrum.
1. An optical device comprising:
a substrate transparent to light in visible wavelength spectrum of 400 nm to 700 nm; and
a plurality of Huygens resonators on the substrate, each of the plurality of the Huygens resonators having a gap “g” between adjacent Huygens resonators of the plurality of the Huygens resonators, each Huygens resonator comprised of a dielectric material with a defined height “h” in the range of 10 nm to 400 nm, and each Huygens resonator having a radius “r” in the range of 10 nm and 400 nm,
wherein the plurality of Huygens resonators form a Huygens metasurface having a dielectric loss value less than 0.1 tangent of delta for light having a wavelength between 400 nm and 700 nm.
2. The optical device of claim 1 , wherein each of the plurality of Huygens resonators is substantially a right circular cylinder or substantially a right elliptical cylinder.
3. The optical device of claim 1 , wherein the plurality of Huygens resonators comprises a first resonator and a second resonator positioned such that the gap “g” between the first resonator and the second resonator is in the range of 10 nm to 400 nm.
4. The optical device of claim 1 , wherein a refractive index of the plurality of Huygens resonators is in the range of 1.5 to 20.
5. The optical device of claim 1 , wherein overall transmission efficiency is greater than 0%.
6. The optical device of claim 1 , wherein each of the plurality of the Huygens resonators comprises titanium dioxide.
7. The optical device of claim 1 , wherein each of the plurality of the Huygens resonators comprises gallium phosphide.
8. The optical device of claim 1 coupled with a MEMS device such that a resulting arrangement is configured to control light passing through the optical device and achieve the dielectric loss value less than 0.1 tangent of delta.
9. The optical device of claim 1 , wherein the optical device is a first optical device coupled to a second optical device, the second optical device comprising a second plurality of Huygens resonators forming a second Huygens metasurface; and wherein the first optical device and the second optical device are movably arranged relative to one another and configured to control phase of the light passing through the first optical device and the second optical device such that the first optical device and the second optical device together have a second dielectric loss value less than 0.1 tangent of delta for light having the wavelength between 400 nm and 700 nm.
10. A resonator that is a Huygens source for a dielectric optical device functional at wavelengths between 400 nm and 700 nm, wherein the resonator is substantially cylindrical and comprises a low-loss material.
11. The resonator of claim 10 , wherein the low dielectric loss material is titanium dioxide.
12. The resonator of claim 10 , wherein the low dielectric loss material is gallium phosphide.
13. The resonator of claim 10 , the resonator having a radius in the range of 10 nm and 400 nm.
14. The resonator of claim 13 , the resonator having a height not greater than four times the radius.