Simultaneous polarization and wavefront control using a planar device
Methods and device for controlling optical scattering are disclosed. An array of 4-fold asymmetric cylinders can act as optical elements scattering electromagnetic waves, where the orientation and dimension of each optical element is determined according to the desired polarization and phase shift response of the device. A Jones matrix can be calculated to determine the fabrication parameters of the optical elements.
1. A device comprising:
a substrate; and
an array of 4-fold asymmetric electromagnetic scattering elements on the substrate,
wherein the 4-fold asymmetric electromagnetic scattering elements are weakly coupled to each other, and have a higher refractive index than the substrate.
2. The device of claim 1 , wherein the substrate is made of silica and the 4-fold asymmetric electromagnetic scattering elements are made of amorphous silicon.
3. The device of claim 2 , wherein the 4-fold asymmetric electromagnetic scattering elements are 4-fold asymmetric cylinders.
4. The device of claim 3 , wherein the 4-fold asymmetric cylinders have a polarization dependent scattering response.
5. The device of claim 4 , wherein a major axis of the 4-fold asymmetric cylinders is oriented according to a desired polarization dependent scattering response.
6. The device of claim 5 , wherein the 4-fold asymmetric cylinders comprise a first group and a second group of 4-fold asymmetric cylinders, the first group having a major axis oriented in a different direction than a major axis of the second group.
7. The device of claim 4 , wherein one or more of a major axis, minor axis, major axis orientation, and height of the 4-fold asymmetric cylinders are configured according to a desired polarization dependent scattering response.
8. The device of claim 4 , wherein one or more of a major axis, minor axis, major axis orientation, and height of the 4-fold asymmetric cylinders are configured so that electromagnetic waves incident on the device with a polarization parallel to the major or minor axis have an unchanged polarization but a shifted phase after exiting the device.
9. The device of claim 3 , wherein the 4-fold asymmetric cylinders are elliptical, rectangular or rhomboidal.
10. The device of claim 8 , wherein the major axis, minor axis, major axis orientation, and height of the 4-fold asymmetric cylinders are determined according to a Jones matrix for the electromagnetic waves incident on and exiting the device.
11. The device of claim 1 , wherein a dimension of the 4-fold asymmetric electromagnetic scattering elements is chosen according to an operational wavelength range of the device.
12. A method comprising:
determining a desired polarization and phase shift of an electromagnetic wave scattered by a device, the device comprising a substrate and an array of 4-fold asymmetric electromagnetic scattering elements on the substrate, wherein the electromagnetic scattering elements have a higher refractive index than the substrate;
calculating a Jones matrix for the scattered electromagnetic wave;
determining a major axis, minor axis, height, and orientation of the major axis for each 4-fold asymmetric electromagnetic scattering element, according to the Jones matrix;
fabricating the device according to the major axis, minor axis, height, and orientation of the major axis of each 4-fold asymmetric electromagnetic scattering element.
13. The method of claim 12 , wherein the 4-fold asymmetric electromagnetic scattering elements are made of amorphous silicon and the substrate is made of silica.
14. The method of claim 13 , wherein the 4-fold asymmetric cylinders are elliptical, rectangular or rhomboidal.
15. A method comprising:
calculating a Jones matrix for an electromagnetic wave scattered by a device, the device comprising a substrate and an array of 4-fold asymmetric electromagnetic scattering elements on the substrate, wherein the electromagnetic scattering elements have a higher refractive index than the substrate;
determining a major axis, minor axis, height, and orientation of the major axis for each 4-fold asymmetric electromagnetic scattering element, according to the Jones matrix;
fabricating the device according to the major axis, minor axis, height, and orientation of the major axis of each 4-fold asymmetric electromagnetic scattering element; and
controlling, by the fabricated device, a polarization and phase shift of the scattered electromagnetic wave.
16. The method of claim 15 , wherein the 4-fold asymmetric electromagnetic scattering elements are made of amorphous silicon and the substrate is made of silica.
17. The method of claim 16 , wherein the 4-fold asymmetric are elliptical, rectangular or rhomboidal.
18. The device of claim 1 , wherein the array of 4-fold asymmetric electromagnetic scattering elements comprises hexagonal regions each having a different phase and polarization profile than adjacent regions.
19. A device comprising:
a substrate; and
an array of 4-fold asymmetric electromagnetic scattering elements on the substrate, wherein:
the 4-fold asymmetric electromagnetic scattering elements have a higher refractive index than the substrate,
the substrate is made of silica and the 4-fold asymmetric electromagnetic scattering elements are made of amorphous silicon,
the 4-fold asymmetric electromagnetic scattering elements are 4-fold asymmetric cylinders,
the 4-fold asymmetric cylinders have a polarization dependent scattering response, and
one or more of a major axis, minor axis, major axis orientation, and height of the 4-fold asymmetric cylinders are configured according to a desired polarization dependent scattering response.
20. A device comprising:
a substrate; and
an array of 4-fold asymmetric electromagnetic scattering elements on the substrate, wherein:
the 4-fold asymmetric electromagnetic scattering elements have a higher refractive index than the substrate,
the substrate is made of silica and the 4-fold asymmetric electromagnetic scattering elements are made of amorphous silicon,
the 4-fold asymmetric electromagnetic scattering elements are 4-fold asymmetric cylinders,
the 4-fold asymmetric cylinders have a polarization dependent scattering response, and one or more of a major axis, minor axis, major axis orientation, and height of the 4-fold asymmetric cylinders are configured so that electromagnetic waves incident on the device with a polarization parallel to the major or minor axis have an unchanged polarization but a shifted phase after exiting the device.
21. The device of claim 20 , wherein the major axis, minor axis, major axis orientation, and height of the 4-fold asymmetric cylinders are determined according to a Jones matrix for the electromagnetic waves incident on and exiting the device.