Optical beam-steering devices and methods utilizing surface scattering metasurfaces
Systems and methods are described herein for an optical beam-steering device that includes an optical transmitter and/or receiver to transmit and/or receive optical radiation from an optically reflective surface. An array of adjustable dielectric resonator elements is arranged on the surface with inter-element spacings less than an optical operating wavelength. A controller applies a pattern of voltage differentials to the adjustable dielectric resonator elements. The pattern of voltage differentials corresponds to a sub-wavelength reflection phase pattern for reflecting the optical electromagnetic radiation. One embodiment of a dielectric resonator element includes first and second dielectric members extending from the surface. The dielectric resonator elements are spaced from one another to form a gap or channel therebetween. A voltage-controlled adjustable refractive index material is disposed within the gap.
1. An optical beam-steering device, comprising:
an optical electromagnetic radiation converter to convert between electric power and optical electromagnetic radiation;
a surface to reflect the optical electromagnetic radiation;
a plurality of adjustable dielectric resonator elements arranged on the surface with inter-element spacings less than an optical operating wavelength to selectively apply a sub-wavelength reflection phase pattern to the optical electromagnetic radiation.
2. The device of claim 1 , further comprising a controller to selectively apply a pattern of voltages to the plurality of dielectric resonator elements, wherein the pattern of voltages corresponds to a pattern of reflection phases of the plurality of dielectric resonator elements.
3. The device of claim 1 , wherein each of the dielectric resonator elements comprises:
a first dielectric member extending from the surface;
a second dielectric member extending from the surface; and
an adjustable refractive index material disposed in a gap between the first and second dielectric members.
4. The device of claim 3 , wherein the first dielectric member comprises a first elongated wall, the second dielectric member comprises a second elongated wall that is substantially parallel to the first wall, and the adjustable refractive index material is disposed within a channel defined by the first and second walls.
5. The device of claim 4 , wherein each of the first and second elongated walls have a length corresponding to an Nth harmonic mode of frequencies within an optical operating bandwidth, such that N antinodes can be realized along the length of the gap between the first and second elongated walls, where N is an integer.
6. The device of claim 5 , wherein each of the first and second elongated walls extends from the surface to a height corresponding to an Mth order harmonic mode of frequencies within the optical operating bandwidth, such that M antinodes can be realized within the gap between the surface and tops of the first and second elongated walls, where M is an integer.
7. The device of claim 5 , wherein the spacing gap between the first and second elongated walls corresponds to a fundamental harmonic mode of frequencies within the optical operating bandwidth.
8. The device of claim 3 , wherein the first dielectric member comprises a first pillar, the second dielectric member comprises a second pillar, and the adjustable refractive index material is disposed between the first and second pillars.
9. The device of claim 3 , wherein each of the first and second dielectric members extends substantially perpendicular from the surface.
10. The device of claim 3 , further comprising a controller to selectively apply voltage differentials to the first and second dielectric members of each of the dielectric resonator elements, wherein each of a plurality of selectable voltage differentials corresponds to (i) an index of refraction of the adjustable refractive index material, and (ii) a reflection phase of each of the respective dielectric resonator elements.
11. The device of claim 1 , wherein each of the plurality of dielectric resonator elements comprises:
a first dielectric member extending from the surface;
a second dielectric member extending from the surface,
wherein the first dielectric member and the second dielectric member are spaced from one another to form a channel therebetween;
an electrically adjustable refractive index material disposed within at least a portion of the channel; and
electrical contacts to receive an applied voltage differential to the first and second dielectric members,
wherein application of a first voltage differential to the first and second dielectric members corresponds to a first reflection phase, and
wherein application of a second voltage differential to the first and second dielectric members corresponds to a second reflection phase.
12. The device of claim 1 , wherein the optical beam-steering device comprises a transmission device with the optical electromagnetic radiation converter configured to convert electric power into optical electromagnetic radiation.
13. The device of claim 1 , wherein the optical beam-steering device comprises a receiving device with the optical electromagnetic radiation converter configured to convert optical electromagnetic radiation into electric power.
14. The device of claim 1 , wherein the optical beam-steering device comprises a transceiver configured to switch between receiving and transmitting optical electromagnetic radiation.
15. The device of claim 1 , wherein the optical beam-steering device comprises a laser to transmit optical electromagnetic radiation and a photodiode to receive optical electromagnetic radiation.
16. The device of claim 1 , wherein each of the dielectric resonator elements comprises:
a first elongated wall;
a second elongated wall; and
an adjustable refractive index material disposed within a channel defined between the first and second elongated walls.
17. The device of claim 16 , wherein the dielectric resonator elements are arranged in a two-dimensional array.
18. The device of claim 16 , wherein each of the elongated walls extends from the surface to a height between approximately 300 and 1500 nanometers.
19. The device of claim 16 , wherein each of the elongated walls extends from the surface to a height between approximately 500 nanometers.
20. The device of claim 16 , wherein each of the elongated walls has a width between approximately 50 and 300 nanometers.
21. The device of claim 16 , wherein each of the elongated walls has a width of approximately 100 nanometers.
22. The device of claim 16 , wherein each of the elongated walls is spaced from each adjacent elongated wall by between approximately 40 and 250 nanometers.
23. The device of claim 16 , wherein each of the elongated walls is uniformly spaced from each adjacent elongated wall by a spacing distance that is between approximately 50 and 300 nanometers.
24. The device of claim 16 , wherein each of the elongated walls is unevenly spaced from adjacent elongated walls by distances between approximately 50 and 300 nanometers.
25. The device of claim 1 , wherein each of the dielectric resonator elements comprises:
a first pillar having a substantially rectangular base;
a second pillar having substantially rectangular base; and
an adjustable refractive index material disposed between the first and second pillars.
26. The device of claim 25 , wherein each of the first and second pillars are substantially cuboid in shape.
27. The device of claim 26 , wherein a length, height, and width of each of the first and second pillars are based on a target resonance for a wavelength within an operational bandwidth.
28. The device of claim 26 , wherein a length, height, and width of each of the first and second pillars are based on a target resonance and Q factor for a wavelength within an operational bandwidth.
29. The device of claim 26 , wherein each of the first and second pillars extends from the surface to a height between approximately 300 and 1500 nanometers.