Integrated optical phased array electronic control
Controlling an optical phased array includes applying optical phase shifts by an array of phase shifter (PS) elements, each PS element applying an optical phase shift based on an input voltage signal applied across first and second terminals of the PS element, providing output voltage signals from an array of driver elements. During a charging time period, each driver element provides an output voltage signal to determine a corresponding input voltage signal applied across at least one of the PS elements; an array of switches control connectivity between the driver elements and respective PS elements; and all of the second terminals of all of the PS elements in the array of PS elements are maintained at a common voltage. The total number of switches in the array of switches is at least as large as the total number of PS elements in the array of PS elements.
1. An apparatus comprising:
an array of emitter elements;
an array of phase shifter elements, each phase shifter element configured to apply an optical phase shift to an optical wave that propagates through the phase shifter element and propagates to a corresponding emitter element, where the optical phase shift is based on an input voltage signal applied across first and second terminals of the phase shifter element;
an array of driver elements, each driver element configured to provide an output voltage signal during a charging time period to determine a corresponding input voltage signal applied across at least one of the phase shifter elements, where all of the second terminals of all of the phase shifter elements in the array of phase shifter elements are maintained at a common voltage during the charging time period; and
an array of switches configured to control connectivity between the driver elements and respective phase shifter elements during the charging time period, where the total number of switches in the array of switches is at least as large as the total number of phase shifter elements in the array of phase shifter elements.
2. The apparatus of claim 1 , wherein the array of phase shifter elements is provided on a photonic integrated circuit.
3. The apparatus of claim 2 , wherein the array of driver elements is provided on an electronic integrated circuit electrically connected to the photonic integrated circuit.
4. The apparatus of claim 3 , wherein the array of switches is provided on the electronic integrated circuit.
5. The apparatus of claim 4 , wherein at least one of the driver elements in the array of driver elements comprises a digital-to-analog converter with an output voltage that is coupled to a plurality of the switches in the array of switches.
6. The apparatus of claim 5 , wherein the electronic integrated circuit includes capacitors coupled to the switches storing charge accumulated from the output voltage signals provided from the driver elements during the charging time period, and the capacitors provide the input voltage signals applied across the phase shifter elements.
7. The apparatus of claim 5 , wherein the output voltage signals are connected to the first terminal of one or more of the phase shifter elements that are selected according to the array of switches, and the input voltage signals are provided based on capacitance characteristics of the phase shifter elements.
8. The apparatus of claim 3 , wherein the array of switches is provided on the photonic integrated circuit.
9. The apparatus of claim 8 , wherein at least two driver elements in the array of driver elements comprise digital-to-analog converters with outputs coupled to different respective rows of phase shifter elements, and a plurality of column enable signals control the connectivity to a selected column of phase shifter elements that consists of a single phase shifter element from each of the rows of phase shifter elements.
10. The apparatus of claim 9 , wherein the input voltage signals are provided based on capacitance characteristics of the phase shifter elements.
11. The apparatus of claim 2 , wherein the array of driver elements is provided on the photonic integrated circuit, and the array of switches is provided on the photonic integrated circuit.
12. The apparatus of claim 11 , wherein at least two driver elements in the array of driver elements comprise digital-to-analog converters with outputs coupled to different respective rows of phase shifter elements, and a plurality of column enable signals control the connectivity to a selected column of phase shifter elements that consists of a single phase shifter element from each of the rows of phase shifter elements.
13. The apparatus of claim 12 , wherein the input voltage signals are provided based on capacitance characteristics of the phase shifter elements.
14. The apparatus of claim 1 , wherein each phase shifter element in the array of phase shifter elements comprises a reverse-biased diode device.
15. The apparatus of claim 14 , wherein at least one of the phase shifter elements in the array of phase shifter elements comprises a plurality of reverse-biased diode devices connected in series with each other.
16. The apparatus of claim 14 , wherein at least one of the phase shifter elements in the array of phase shifter elements comprises a reverse-biased diode device connected in series with an inductor.
17. The apparatus of claim 1 , wherein each switch in the array of switches comprises at least a first, second, and third terminal, where a flow of current between the first and second terminals is controlled based on a voltage or current applied at the third terminal.
18. A method for controlling an optical phased array, the method comprising:
applying optical phase shifts by an array of phase shifter elements, each phase shifter element applying an optical phase shift to an optical wave that propagates through the phase shifter element and propagates to a corresponding emitter element of the optical phased array, where the optical phase shift is based on an input voltage signal applied across first and second terminals of the phase shifter element;
providing output voltage signals from an array of driver elements, each driver element providing an output voltage signal during a charging time period to determine a corresponding input voltage signal applied across at least one of the phase shifter elements, where all of the second terminals of all of the phase shifter elements in the array of phase shifter elements are maintained at a common voltage during the charging time period; and
managing an array of switches to control connectivity between the driver elements and respective phase shifter elements during the charging time period, where the total number of switches in the array of switches is at least as large as the total number of phase shifter elements in the array of phase shifter elements.
19. The method of claim 18 , wherein the charging time period comprises a period of a periodic refresh cycle during which the input voltage signals are refreshed based on capacitance characteristics of the phase shifter elements.
20. The method of claim 18 , wherein managing the array of switches to control connectivity of the driver elements comprises selecting a first switch coupled to a first phase shifter element in a group of the plurality of phase shifter elements to allow current flow to the first phase shifter element during the charging time period, and selecting switches coupled to all other phase shifter elements in the group other than the first phase shifter element to substantially prevent current flow during the charging time period.