Plasma dispersion effect for metasurface tuning
An active metasurface that provides low-loss and high-bandwidth modulation control of light includes a number of cells arranged on a substrate. A controller dynamically alters a voltage differential supplied to the electrodes of each of the cells is adapted to alter refractive index of each of the high-index dielectric blocks in order to controllably steer light exiting the cell.
1. A device, comprising:
a metasurface comprising a number of cells arranged on a substrate, each of the cells including:
a high-index dielectric block including an interface between a positively-doped material and a negatively-doped material; and
electrodes configured to provide a voltage differential across the high-index dielectric block to flow current along a current path that passes through the high-index dielectric block, at least a portion of the current path being substantially parallel to a plane defined by the metasurface.
2. The device of claim 1 , wherein each of the cells has dimensions that provide a Mie resonance mode to enhance an electric field component of light of a target wavelength.
3. The device of claim 1 , wherein each of the cells is doped to have a positive charge density that increases in a first direction of the cell and a negative charge density that increases in a second opposite direction of the cell.
4. The device of claim 3 , wherein the positive charge density and the negative charge density vary in a direction that is generally parallel to the plane defined by the metasurface.
5. The device of claim 1 , further comprising a controller that dynamically alters a voltage differential supplied to the electrodes of each of the cells to alter a refractive index of each of the high-index dielectric blocks in order to controllably steer light exiting the cell.
6. The device of claim 5 , wherein the cell is reverse biased such that the controller applies a positive voltage to a first electrode in contact with a negatively-doped region and a negative voltage to a second electrode that is in contact with a positively-doped region.
7. The device of claim 1 , wherein the high-index dielectric block is a silicon resonator.
8. A device for controlling a metasurface to steer light, the device comprising:
a number of cells arranged on a substrate, each of the cells configured to receive light and including at least:
a high-index dielectric block including an interface between a positively-doped material and a negatively-doped material; and
electrodes configured to supply a voltage differential to the cell to flow current along a current path that passes through the high-index dielectric block, at least a portion of the current path being substantially parallel to a plane defined by the metasurface; and
dynamically altering a voltage differential supplied to the electrodes of each of the cells to alter a refractive index of each of the high-index dielectric blocks in order to controllably steer light exiting the cell.
9. The device of claim 8 , wherein each of the cells has dimensions that provide a Mie resonance mode to enhance an electric field component of light of a target wavelength.
10. The device of claim 8 , wherein each of the cells is doped to have a positive charge density that increases in a first direction of the cell and a negative charge density that increases in a second opposite direction of the cell.
11. The device of claim 10 , wherein the positive charge density and the negative charge density vary in a direction that is generally parallel to the plane defined by the metasurface.
12. The device of claim 10 , wherein the positive charge density and the negative charge density varies in a direction that is generally perpendicular to the plane defined by the metasurface.
13. The device of claim 10 , wherein the high-index dielectric block is a silicon resonator.
14. The device of claim 10 , further comprising a controller that dynamically alters a voltage differential supplied to the electrodes of each of the cells to alter a refractive index of each of the high-index dielectric blocks in order to controllably steer light exiting the cell.
15. The device of claim 14 , wherein the cell is reverse biased such that the controller applies a positive voltage to a first electrode in contact with a negatively-doped region and a negative voltage to a second electrode that is in contact with a positively-doped region.
16. A system comprising:
at least one cell including a high-index dielectric block including a junction between a positively-doped material and a negatively-doped material;
electrodes arranged on opposite sides of the at least one cell and each being separated from a phase-shifting portion of the high-index dielectric block, and
circuitry configured to supply a voltage differential to the electrodes and to dynamically alter the voltage differential to control a refractive index of the high-index dielectric block and thereby controllably steer light exiting the cell.
17. The system of claim 16 , wherein each of the cells has dimensions that provide a Mie resonance mode to enhance an electric field component of light of a target wavelength.
18. The system of claim 16 , wherein each of the cells is doped to have a positive charge density that increases in a first direction of the cell and a negative charge density that increases in a second opposite direction of the cell.
19. The system of claim 18 , wherein the positive charge density and the negative charge density varies in a direction that is generally perpendicular to a plane defined by a metasurface including the at least one cell.