Sidelobe suppression in metasurface devices
A transceiver system may include first and second metasurfaces, such as radio frequency (RF) metasurfaces or optically reflective tunable liquid crystal metasurfaces (LCMs). In one specific example, a transmit LCM may be tuned by a controller to steerably reflect incident optical radiation at a target transmit steering angle. A laser or other optical radiation source may transmit optical radiation to the transmit LCM at a first angle of incidence. The controller may tune the second tunable LCM to steerably receive optical radiation at a target receive steering angle corresponding to the target transmit steering angle. The received optical radiation may be reflected at a second angle of incidence to a detector.
1. A system, comprising:
a first metasurface to steerably transmit incident electromagnetic radiation at a transmit steering angle;
a radiation source to transmit electromagnetic radiation to the first metasurface at a first angle of incidence with respect to the first metasurface;
a second metasurface to steerably receive electromagnetic radiation at a receive steering angle corresponding to the transmit steering angle; and
a detector to detect electromagnetic radiation reflected by the second metasurface from a second angle of incidence with respect to the second metasurface, wherein the first angle of incidence is different than the second angle of incidence.
2. The system of claim 1 , wherein the first angle of incidence and the second angle of incidence are selected to offset a dominant sidelobe of the first metasurface with respect to a dominant sidelobe of the second metasurface for each of a plurality of transmit steering angles.
3. The system of claim 1 , wherein a difference between the first angle of incidence and the second angle of incidence is selected to generate asymmetric transmit and receive radiation patterns for a given transmit steering angle and corresponding receive steering angle.
4. The system of claim 3 , wherein the difference between the first angle of incidence and the second angle of incidence corresponds to one diffraction order of the first and second metasurfaces.
5. The system of claim 1 , wherein the first metasurface is configured to steerably transmit incident microwave radiation at the first transmit steering angle, and
wherein the second metasurface is configured to steerably receive microwave radiation at the receive steering angle.
6. The system of claim 1 , wherein the first metasurface is configured to steerably transmit incident optical radiation at the first transmit steering angle, and
wherein the second metasurface is configured to steerably receive optical radiation at the receive steering angle.
7. The system of claim 1 , wherein the first metasurface comprises a radio frequency (RF) metasurface.
8. The system of claim 1 , wherein the first metasurface comprises an optically reflective tunable metasurface.
9. The system of claim 8 , wherein the first optically reflective tunable metasurface comprises a liquid crystal metasurface (LCM).
10. The system of claim 8 , wherein the second optically reflective tunable metasurface comprises a liquid crystal metasurface (LCM).
11. The system of claim 1 , wherein radiation source comprises an optical radiation source.
12. The system of claim 11 , wherein the optical radiation source comprises a laser to emit light at an operating wavelength.
13. The system of claim 12 , wherein the operating wavelength is one of 850 nanometers, 905 nanometers, and 1550 nanometers.
14. The system of claim 12 , wherein the laser comprises a collimating lens.
15. The system of claim 1 , wherein each of the first and second metasurfaces comprises an optically reflective tunable metasurface.
16. The system of claim 15 , wherein each of the first and second optically reflective tunable metasurfaces comprises:
an array of optical resonant antennas arranged at sub-wavelength intervals on a reflective surface, and
liquid crystal positioned in optical field regions of each optical resonant antenna in the array.
17. The system of claim 16 , wherein a difference between the first angle of incidence and the second angle of incidence corresponds to one diffraction order of the sub-wavelength array of optical resonant antennas.
18. The system of claim 16 , further comprising a voltage controller to control the steering angles of the first and second optically reflective LCMs by selectively applying voltage differential bias patterns to the liquid crystal of the respective arrays of optical resonant antennas of each of the first and second optically reflective tunable metasurfaces.
19. A transceiver system, comprising:
a first metasurface to steer incident radiation at a transmit steering angle;
a radiation source to transmit radiation to the first metasurface at a first angle of incidence with respect to the first tunable metasurface;
a second metasurface to steerably receive radiation at a receive steering angle corresponding to the transmit steering angle; and
a detector to detect a power level of the radiation received by the second metasurface that is directed to the detector at a second angle of incidence defined with respect to the second metasurface, wherein the first angle of incidence is different than the second angle of incidence.
20. The system of claim 19 , wherein the first and second metasurfaces each comprise a tunable, optically reflective liquid crystal metasurface (LCM) with an array of optical resonant antennas arranged at sub-wavelength intervals on a reflective surface.
21. The system of claim 19 , wherein the first angle of incidence and the second angle of incidence are selected to offset a dominant sidelobe of the first metasurface with respect to a dominant sidelobe of the second metasurface for a given transmit steering angle.
22. The system of claim 19 , wherein a difference between the first angle of incidence and the second angle of incidence is selected to generate asymmetric transmit and receive radiation patterns for a given transmit steering angle.
23. A transceiver system, comprising:
a first optically reflective tunable liquid crystal metasurface (LCM) to reflect incident light at a transmit steering angle;
a laser to transmit light to the first LCM at a first angle of incidence with respect to the first tunable metasurface;
a second optically reflective tunable LCM to steerably receive light at a receive steering angle corresponding to the transmit steering angle; and
a detector to detect light reflected by the second optically reflective tunable LCM from a second angle of incidence with respect to the second tunable metasurface, wherein the first angle of incidence is different than the second angle of incidence.
24. The system of claim 23 , wherein a difference between the first angle of incidence and the second angle of incidence corresponds to one diffraction order of the first and second optically reflective tunable LCMs.
25. The system of claim 23 , wherein a difference between the first angle of incidence and the second angle of incidence is selected to generate asymmetric transmit and receive radiation patterns for each transmit steering angle and corresponding receive steering angle.