Control circuitry for 2D optical metasurfaces
A 2D hologram system with a matrix addressing scheme is provided. The system may include a 2D array of sub-wavelength hologram elements integrated with a refractive index tunable core material on a wafer substrate. The system may also include a matrix addressing scheme coupled to the 2D array of sub-wavelength hologram elements and configured to independently control each of the sub-wavelength hologram elements by applying a voltage.
1. A method of operating a 2D hologram system having a 2D array of hologram elements with a matrix addressing scheme, the method comprising:
adjusting a binary voltage on a first row to change the first row from an “off” state to an “on” state;
applying a first analog voltage to a first column such that the first analog voltage is stored in a first hologram element in the first column and the first row;
changing the first row to an “off” state;
adjusting a second row from an “off” state to an “on” state;
applying a second analog voltage to a second column such that the second analog voltage is stored in a second hologram element in the second column and the second row,
wherein each of the 2D array of sub-wavelength hologram elements is integrated with a refractive index tunable core material on a wafer substrate comprising a matrix control circuitry having a 2D array of CMOS transistors.
2. The method of claim 1 , wherein the refractive index tunable core material comprises EP polymer.
3. A method of operating a hologram system having a 2D array of sub-wavelength hologram elements, with a passive matrix addressing scheme, the method comprising:
applying a first analog voltage to a first ROW line, wherein a first row of a 2D array of sub-wavelength hologram elements is coupled to the first ROW line;
applying a second analog voltage to a first COLUMN line, wherein a first column of the 2D array of sub-wavelength hologram elements is coupled to the first COLUMN line;
applying a third analog voltage to the first ROW line or to the first COLUMN line in a refreshing time shorter than a relaxation time of a refractive index tunable core material integrated with a pair of dielectric pillars of each of the 2D array of sub-wavelength hologram elements;
wherein a first hologram element in the first row and the first column has a first total analog voltage equal to a sum of the first analog voltage and the second analog voltage,
wherein a second total analog voltage is equal to the sum of the third analog voltage and the first or second analog voltage,
if the second total analog voltage is smaller than the first total analog voltage, the state of the refractive index tunable core material of the first hologram element remains substantially constant, or
if the second total analog voltage is greater than the first total analog voltage, the state of the refractive index tunable core material of the first hologram element is changed according to the second total analog voltage.
4. The method of claim 3 , further comprising:
applying a fourth analog voltage to a second ROW line, wherein a second row of the 2D array of sub-wavelength hologram elements is coupled to the second ROW line; and
applying a fifth analog voltage to a second COLUMN line, wherein a second column of the 2D array of sub-wavelength hologram elements is coupled to the second COLUMN line.
5. The method of claim 3 , wherein the second hologram element has a total analog voltage equal to the sum of the fourth analog voltage and the fifth analog voltage, such that the second hologram element is independently controlled from the first hologram element.
6. The method of claim 3 , wherein the refractive index tunable core material comprises liquid crystals or chalcogenide glasses.