Method and system for an all-optical wafer acceptance test

1. A method comprising:

receiving a first input optical signal via a first grating coupler coupled to an interferometer;

propagating the first input optical signal from the first grating coupler to the interferometer;

obtaining a first measurement of an output optical signal received by a second grating coupler coupled to the interferometer, wherein the output optical signal is output by the interferometer based on the first input optical signal;

receiving a second input optical signal via a third grating coupler;

communicating a portion of the second input optical signal to each photodiode of a plurality of photodiodes via a splitter;

biasing a first phase modulator of the interferometer using a voltage generated by the plurality of photodiodes based on the second input optical signal;

obtaining a second measurement of the output optical signal received by the second grating coupler while the first phase modulator is biased by the voltage; and

extracting a phase shift efficiency of the first phase modulator based on the voltage, the first measurement and the second measurement.

2. The method according to claim 1 , further comprising reverse biasing the first phase modulator using the voltage.

3. The method according to claim 1 , further comprising forward biasing the first phase modulator using the voltage.

4. The method according to claim 1 , further comprising regulating the voltage using a series-coupled resistor and a pair of forward-biased photodiodes coupled to ground.

5. The method according to claim 1 , further comprising coupling a third input optical signal to a fourth grating coupler.

6. The method according to claim 5 , further comprising generating a second voltage using a second plurality of photodiodes based on the third input optical signal.

7. The method according to claim 6 , further comprising biasing a second phase modulator of the interferometer using the second voltage.

8. The method according to claim 7 , further comprising obtaining a third measurement of the output optical signal while the second phase modulator is biased by the second voltage.

9. The method according to claim 1 , wherein the plurality of photodiodes comprise germanium.

10. A system comprising:

an optical transceiver on a chip, the optical transceiver comprising first, second, and third grating couplers, an interferometer comprising first and second phase modulators, a splitter, and a plurality of photodiodes, the optical transceiver being operable to:

receive a first input optical signal in the chip via the first grating coupler coupled to the interferometer;

propagate the first input optical signal to the interferometer;

propagate an output optical signal from the interferometer based on the first input optical signal out of the chip via the second grating coupler for a first measurement of the interferometer;

receive a second input optical signal via a third grating coupler;

communicate a portion of the second input optical signal to each photodiode of the plurality of photodiodes via the splitter;

bias the first phase modulator using a voltage generated by the plurality of photodiodes based on the second input optical signal;

measure the output optical signal for a second measurement of the interferometer with the first phase modulator being biased by the voltage; and

extract a phase shift efficiency of the first phase modulator based on the voltage, the first measurement and the second measurement.

11. The system according to claim 10 , wherein the optical transceiver is operable to reverse bias the first phase modulator using the generated voltage.

12. The system according to claim 10 , wherein the optical transceiver is operable to forward bias the first phase modulator using the generated voltage.

13. The system according to claim 10 , wherein the optical transceiver is operable to regulate the generated voltage using a series-coupled resistor and a pair forward-biased photodiodes coupled to ground.

14. The system according to claim 10 , wherein the optical transceiver is operable to receive a third input optical signal via a fourth grating coupler.

15. The system according to claim 14 , wherein the optical transceiver is operable to generate a second voltage using a second plurality of photodiodes based on the third input optical signal.

16. The system according to claim 15 , wherein the optical transceiver is operable to bias the second phase modulator using the second voltage.

17. The system according to claim 16 , wherein a measurement of the output optical signal comprises a third measurement of the interferometer with the second phase modulator being biased by the second voltage.

18. The system according to claim 10 , wherein the chip comprises a complementary metal oxide semiconductor (CMOS) die and the plurality of photodiodes comprise germanium.

19. A system comprising:

an interferometer including a first phase modulator;

a plurality of photodiodes;

a splitter connected to each photodiode of the plurality of photodiodes;

a first coupler configured to receive a first input optical signal for the interferometer;

a second coupler configured to receive an output optical signal from the interferometer based on the first input optical signal;

a third coupler configured to receive a second input optical signal and communicate a portion of the second input optical signal to each photodiode of the plurality of photodiodes via the splitter; and

wherein the plurality of photodiodes is configured to bias the first phase modulator via a voltage based on the second input optical signal.

20. The system of claim 19 , wherein the voltage based on the second input optical signal is set by selecting a number of photodiodes of the plurality of photodiodes that to connect in series with the first phase modulator.