Digital input circuit design for photonic integrated circuit

1. A device comprising:

a photonic integrated circuit (PIC) comprising an optical phased array, the optical phased array comprising multiple array elements, each array element comprising (i) an antenna element configured to transmit or receive optical signals and (ii) a phase modulator configured to phase-shift the optical signals transmitted or received by the antenna element; and

multiple digital register in integrated circuit (DRIIC) cells, each DRIIC cell associated with one of the array elements, the DRIIC cells configured to receive digital inputs and to provide outputs to the phase modulators of the associated array elements in order to control the phase-shifts of the optical signals transmitted or received by the antenna elements based on the digital inputs;

wherein each DRIIC cell comprises a register configured to store multiple values and output selective values based on the DRIIC cell's digital inputs.

2. The device of claim 1 , wherein each DRIIC cell is configured to provide output voltages to the phase modulator of the associated array element, the output voltages configured to adjust the phase-shift provided by the phase modulator of the associated array element.

3. The device of claim 2 , wherein the DRIIC cells are configured to function as digital-to-analog converters that convert the digital inputs into analog output voltages spanning a specific range of voltages.

4. The device of claim 1 , wherein each DRIIC cell has a size that substantially matches a size of the associated array element.

5. The device of claim 1 , wherein each DRIIC cell further comprises:

amplifiers configured to amplify outputs from the register to produce output voltages;

wherein the register is configured to output the selective values to the amplifiers.

6. The device of claim 5 , wherein each DRIIC cell further comprises:

a demultiplexer configured to obtain the DRIIC cell's digital inputs.

7. The device of claim 1 , wherein a layer of the DRIIC cells is flip-chip bonded to the photonic integrated circuit.

8. The device of claim 1 , wherein:

the optical phased array includes at least one million array elements; and

the device includes at least one million DRIIC cells.

9. A device comprising:

a photonic integrated circuit (PIC) comprising an optical phased array, the optical phased array comprising multiple array elements, each array element comprising (i) an antenna element configured to transmit or receive optical signals and (ii) a phase modulator configured to phase-shift the optical signals transmitted or received by the antenna element; and

multiple digital register in integrated circuit (DRIIC) cells, each DRIIC cell associated with one of the array elements, the DRIIC cells configured to receive digital inputs and to provide outputs to the phase modulators of the associated array elements in order to control the phase-shifts of the optical signals transmitted or received by the antenna elements based on the digital inputs;

wherein each DRIIC cell is configured to provide output voltages to the phase modulator of the associated array element, the output voltages configured to adjust the phase-shift provided by the phase modulator of the associated array element;

wherein each phase modulator comprises a thermal resonator having a micro-ring resonator and a heater; and

wherein the output voltages are configured to adjust heating provided by the heater.

10. A device comprising:

a photonic integrated circuit (PIC) comprising an optical phased array, the optical phased array comprising multiple array elements, each array element comprising (i) an antenna element configured to transmit or receive optical signals and (ii) a phase modulator configured to phase-shift the optical signals transmitted or received by the antenna element; and

multiple digital register in integrated circuit (DRIIC) cells, each DRIIC cell associated with one of the array elements, the DRIIC cells configured to receive digital inputs and to provide outputs to the phase modulators of the associated array elements in order to control the phase-shifts of the optical signals transmitted or received by the antenna elements based on the digital inputs;

wherein each DRIIC cell is configured to provide output voltages to the phase modulator of the associated array element, the output voltages configured to adjust the phase-shift provided by the phase modulator of the associated array element;

wherein each phase modulator comprises a PN junction modulator; and

wherein the output voltages are configured to adjust a charge carrier density of a waveguide.

11. A method comprising:

using an optical phased array of a photonic integrated circuit (PIC) to transmit or receive optical signals, the optical phased array comprising multiple array elements, each array element comprising (i) an antenna element configured to transmit or receive the optical signals and (ii) a phase modulator configured to phase-shift the optical signals transmitted or received by the antenna element; and

using multiple digital register in integrated circuit (DRIIC) cells to control the phase modulators, each DRIIC cell associated with one of the array elements, the DRIIC cells receiving digital inputs and providing outputs to the phase modulators of the associated array elements in order to control the phase-shifts of the optical signals transmitted or received by the antenna elements based on the digital inputs;

wherein each DRIIC cell comprises a register configured to store multiple values and output selective values based on the DRIIC cell's digital inputs.

12. The method of claim 11 , wherein each DRIIC cell provides output voltages to the phase modulator of the associated array element, the output voltages adjusting the phase-shift provided by the phase modulator of the associated array element.

13. The method of claim 12 , wherein:

each phase modulator comprises a thermal resonator having a micro-ring resonator and a heater; and

the output voltages adjust heating provided by the heater.

14. The method of claim 12 , wherein:

each phase modulator comprises a PN junction modulator; and

the output voltages adjust a charge carrier density of a waveguide.

15. The method of claim 12 , wherein the DRIIC cells function as digital-to-analog converters that convert the digital inputs into analog output voltages spanning a specific range of voltages.

16. The method of claim 11 , wherein each DRIIC cell has a size that substantially matches a size of the associated array element.

17. The method of claim 11 , wherein each DRIIC cell further comprises:

amplifiers configured to amplify outputs from the register to produce output voltages;

wherein the register is configured to output the selective values to the amplifiers.

18. The method of claim 17 , wherein each DRIIC cell further comprises:

a demultiplexer configured to obtain the DRIIC cell's digital inputs.

19. The method of claim 11 , wherein a layer of the DRIIC cells is flip-chip bonded to the photonic integrated circuit.

20. The method of claim 11 , wherein:

the optical phased array includes at least one million array elements; and

the DRIIC cells include at least one million DRIIC cells.