Optical phased array using guided resonance with backside reflectors
Methods and systems for controlling the phase of electromagnetic waves are disclosed. A device can consist of a guided resonance grating layer, a spacer, and a reflector. A plurality of devices, arranged in a grid pattern, can control the phase of reflected electromagnetic phase, through refractive index control. Carrier injection, temperature control, and optical beams can be applied to control the refractive index.
1. A device to control phase of electromagnetic waves, comprising:
a resonance layer capable of sustaining a guided resonance of electromagnetic waves;
a reflector layer; and
a spacer layer between the reflector layer and the resonance layer,
wherein the resonance layer is a grating comprising parallel beams and the spacer layer is made of air and the parallel beams are suspended, at each end, on a side structure.
2. The device of claim 1 , wherein the grating is made of silicon.
3. The device of claim 2 , wherein the reflector layer is a metallic layer.
4. The device of claim 3 , wherein the spacer layer is made of silicon dioxide.
5. The device of claim 4 , further comprising a first transparent electrode layer between the resonance layer and the spacer layer, and a second transparent electrode layer on a surface of the resonance layer opposite to that of the first transparent electrode layer.
6. The device of claim 5 , wherein the first and second transparent electrode layers are made of indium tin oxide.
7. An array to control phase of electromagnetic waves comprising:
a plurality of devices according to claim 5 , arranged in a grid pattern.
8. The device of claim 2 , wherein the reflector layer is a silicon grating.
9. An array to control phase of electromagnetic waves comprising:
a plurality of devices according to claim 1 , arranged in a grid pattern.
10. A method to control phase of electromagnetic waves, comprising:
providing an array of devices arranged in a grid pattern, each device including
a resonance layer capable of sustaining a guided resonance of electromagnetic waves,
a reflector layer, and
a spacer layer between the reflector layer and the resonance layer,
wherein the resonance layer is a grating comprising parallel beams and the spacer layer is made of air and the parallel beams are suspended, at each end, on a side structure;
calculating a desired phase pattern for electromagnetic waves reflected by the array; and
controlling the refractive index of each device according to the desired phase pattern.
11. The method of claim 10 , further comprising measuring a phase pattern of electromagnetic waves incident on the array.
12. The method of claim 10 , wherein the grating is made of silicon.
13. The method of claim 12 , wherein the reflector layer is a metallic layer.
14. The method of claim 13 , wherein the spacer layer is made of silicon dioxide.
15. The method of claim 14 , further comprising a first transparent electrode layer between the resonance layer and the spacer layer, and a second transparent electrode layer on a surface of the resonance layer opposite to that of the first transparent electrode layer.
16. The method of claim 15 , wherein the first and second transparent electrode layers are made of indium tin oxide.
17. The method of claim 15 , wherein controlling the refractive index of each device comprises injecting a current through the first and second transparent electrode layers of each device, wherein the current injected in each device is according to the desired phase pattern.
18. The method of claim 17 , wherein at least one current value injected in a device of the array is different from at least one other current value injected in a different device of the array.
19. The method of claim 12 , wherein the reflector layer is a silicon grating.