Photonic apparatus with bias control to provide substantially constant responsivity of a photodetector

1. An apparatus comprising:

a first photodetector, to receive an optical input and provide a corresponding electrical output;

a second photodetector coupled with the first photodetector, wherein the second photodetector is free from receipt of the optical input; and

circuitry coupled with the first and second photodetectors, to: generate a bias voltage, based at least in part on a dark current generated by the second photodetector in an absence of the optical input; and provide the generated bias voltage to the first photodetector, wherein the first photodetector is to provide a substantially constant ratio of the electrical output to optical input in response to the provision of the generated bias voltage, wherein the circuitry includes a dark current reference source, wherein an anode of the second photodetector is coupled with the dark current reference source, wherein an anode voltage of the second photodetector is based at least in part on a dark current reference provided by the dark current reference source, wherein a cathode bias voltage of the second photodetector is based at least in part on the anode voltage of the second photodetector.

2. The apparatus of claim 1 , wherein the circuitry is to adjust the dark current generated by the second photodetector in the absence of the optical input when the optical input exceeds a power level threshold, and correspondingly adjust the bias voltage based at least in part on the adjusted dark current.

3. The apparatus of claim 2 , wherein to correspondingly adjust the bias voltage, the circuitry is to lower the bias voltage.

4. The apparatus of claim 1 , wherein the first and second photodetectors comprise silicon waveguides.

5. The apparatus of claim 1 , wherein the first and second photodetectors have substantially identical optical and electrical parameters.

6. The apparatus of claim 1 , wherein the circuitry is to replicate the cathode bias voltage of the second photodetector on the first photodetector, to provide the substantially constant ratio of the electrical output to optical input of the first photodetector.

7. The apparatus of claim 1 , wherein the apparatus comprises a photonic integrated circuit.

8. The apparatus of claim 1 , wherein the apparatus comprises a transceiver.

9. A method, comprising:

receiving, by a first photodetector of an apparatus, an optical input, wherein the first photodetector is to provide a corresponding electrical output in response to receiving the optical input, and wherein the first photodetector is coupled with a second photodetector of the apparatus;

generating, by a circuitry coupled with the first and second photodetectors of the apparatus, a bias voltage, based at least in part on a dark current generated by the second photodetector in an absence of the optical input;

providing, by the circuitry, the generated bias voltage to the first photodetector, wherein the first photodetector is to provide a substantially constant ratio of the electrical output to optical input in response to the providing of the generated bias voltage;

adjusting, by the circuitry, the dark current generated by the second photodetector in the absence of the optical input when the optical input exceeds a power level threshold;

correspondingly adjusting, by the circuitry, the bias voltage based at least in part on the adjusted dark current; and

generating, by the circuitry, a dark current reference, based at least in part on a table including dark current values and corresponding responsivity values, wherein the responsivity values comprise a ratio of the electrical output to optical input, wherein the adjusting of the dark current includes providing, by the circuitry, the dark current based at least in part on the generated dark current reference.

10. The method of claim 9 , wherein correspondingly adjusting the bias voltage includes lowering, by, the circuitry, the bias voltage.

11. The method of claim 9 , wherein the apparatus comprises a photonic integrated circuit.

12. A computing device, comprising:

a processor, to generate data; and

a transceiver coupled with the processor, to transmit the generated data, wherein the transceiver includes: a first photodetector, to receive an optical input and provide a corresponding electrical output; a second photodetector coupled with the first photodetector, wherein the second photodetector is free from receipt of the optical input; and circuitry coupled with the first and second photodetectors, to: generate a bias voltage, based at least in part on a dark current generated by the second photodetector in an absence of the optical input; and provide the generated bias voltage to the first photodetector, wherein the first photodetector is to provide a substantially constant ratio of the electrical output to optical input in response to the provision of the generated bias voltage, wherein the circuitry includes logic to generate the dark current based at least in part on a look-up table that provides dark current values that correspond to responsivity values of the first photodetector, wherein the responsivity values comprise a substantially constant value.

13. The computing device of claim 12 , wherein the circuitry is to adjust the dark current generated by the second photodetector in the absence of the optical input when the optical input exceeds a power level threshold, and correspondingly adjust the bias voltage based at least in part on the adjusted dark current.

14. The computing device of claim 12 , wherein the first and second photodetectors comprise silicon waveguides.

15. The computing device of claim 12 , wherein the first and second photodetectors have substantially identical optical and electrical parameters.

16. The computing device of claim 12 , wherein the computing device comprises a server or a data center.