Systems, devices, and methods for polarization recovery
A polarization recovery device comprises an input that receives a first optical signal with unknown polarization and with at least one signal parameter at an initial value, a first output that outputs a second optical signal with known polarization and with the at least one signal parameter at or near the initial value, and a recovery block that generates the second optical signal based on the first optical signal.
1. A polarization recovery device, comprising:
an input that receives a first optical signal with unknown polarization and with at least one signal parameter at an initial value;
a first output that outputs a second optical signal with known polarization and with the at least one signal parameter at a maximum possible value at a particular instance in time;
a recovery block that generates the second optical signal based on the first optical signal; and
a splitter coupled to the input and that splits the first optical signal to output a first signal component of the first optical signal and a second signal component of the first optical signal, wherein the recovery block includes:
a set of phase shifters including a first phase shifter that is closest to an output of the splitter compared to other phase shifters in the set of phase shifters; and
a set of optocouplers including a first optocoupler coupled between the output of the splitter and the first phase shifter.
2. The polarization recovery device of claim 1 , wherein the splitter causes the first signal component and the second signal component to have a substantially same polarization.
3. The polarization recovery device of claim 2 , wherein the substantially same polarization corresponds to transverse electric (TE) polarization or transverse magnetic (TM) polarization.
4. The polarization recovery device of claim 1 , wherein the recovery block includes:
a first waveguide section that forms a first optical path for the first signal component; and
a second waveguide section that forms a second optical path for the second signal component.
5. The polarization recovery device of claim 4 , wherein the set of phase shifters further include second and third phase shifters coupled to the second waveguide section at first points within the recovery block.
6. The polarization recovery device of claim 5 , wherein the set of optocouplers further includes second and third optocouplers coupled to the first waveguide section and the second waveguide section at second points within the recovery block.
7. The polarization recovery device of claim 6 , wherein the set of phase shifters includes only the first, second, and third phase shifters, and wherein the set of optocouplers includes only the first, second, and third optocouplers.
8. The polarization recovery device of claim 6 , wherein each second point is located after a respective first point along the second optical path.
9. The polarization recovery device of claim 1 , further comprising:
a second output that outputs a third optical signal; and
a feedback device coupled to the second output.
10. The polarization recovery device of claim 9 , wherein the recovery block uses feedback from the feedback device to generate the second optical signal while providing substantially glitch-free reset operations for one or more phase shifters of the set of phase shifters.
11. The polarization recovery device of claim 1 , further comprising:
a controller that:
determines to perform a reset operation for a second phase shifter of the set of phase shifters based on one or more factors associated with the second phase shifter;
generates at least one control signal to be applied to at least the first phase shifter during the reset operation to keep the at least one signal parameter of the second optical signal within acceptable limits; and
output the at least one control signal to at least the first phase shifter.
12. The polarization recovery device of claim 11 , wherein the set of phase shifters includes a third phase shifter, wherein the at least one control signal includes a first control signal that the controller applies to the first phase shifter during the reset operation and a second control signal applied to the third phase shifter during the reset operation, and wherein the controller generates the first control signal and the second control signal to rise and fall together during the reset operation.
13. A receiver, comprising:
a polarization recovery device including:
an input that receives a first optical signal with unknown polarization and with at least one signal parameter at an initial value;
a first output that outputs a second optical signal with known polarization and with the at least one signal parameter at a maximum possible value at a particular instance in time;
a recovery block that generates the second optical signal based on the first optical signal; and
a splitter coupled to the input and that splits the first optical signal to output a first signal component of the first optical signal and a second signal component of the first optical signal, wherein the recovery block includes:
a set of phase shifters including a first phase shifter that is closest to an output of the splitter compared to other phase shifters in the set of phase shifters; and
a set of optocouplers including a first optocoupler coupled between the output of the splitter and the first phase shifter.
14. The receiver of claim 13 , wherein the recovery block includes:
a first waveguide section that forms a first optical path within the recovery block; and
a second waveguide section coupled to the first output and that forms a second optical path within the recovery block.
15. The receiver of claim 14 , wherein the recovery block includes:
a second output coupled to the second waveguide section and that outputs a third optical signal; and
a feedback device coupled to the second output, wherein the recovery block uses feedback from the feedback device to generate the second optical signal.
16. The receiver of claim 15 , wherein the recovery block further includes:
second and third phase shifters coupled to the second waveguide section at first points within the recovery block; and
second and third optocouplers coupled to the first waveguide section and the second waveguide section at second points within the recovery block, wherein each second point is located after a respective first point along the second optical path.
17. The receiver of claim 16 , wherein the feedback device includes:
a detector that detects the third optical signal; and
a controller that generates electrical signals for electrodes of the first, second, and third phase shifters based on output of the detector.
18. The receiver of claim 13 , further comprising:
a demultiplexer that demultiplexes the second optical signal to form a plurality of optical signals with different wavelengths;
a plurality of detector blocks coupled to the demultiplexer, each detector block detecting a respective optical signal in the plurality of optical signals; and
processing circuitry that extracts data from the plurality of optical signals based on output of the plurality of detector blocks.
19. A system, comprising:
a transmitter that transmits a first optical signal;
an optical transmission line that carries the first optical signal; and
a receiver, comprising:
a polarization recovery device including:
an input coupled to the optical transmission line and that receives the first optical signal with unknown polarization and with at least one signal parameter at an initial value;
a first output that outputs a second optical signal with known polarization and with the at least one signal parameter at a maximum possible value at a particular instance in time;
a recovery block that generates the second optical signal based on the first optical signal; and
a splitter coupled to the input and that splits the first optical signal to output a first signal component of the first optical signal and a second signal component of the first optical signal, wherein the recovery block includes:
a set of phase shifters including a first phase shifter that is closest to an output of the splitter compared to other phase shifters in the set of phase shifters; and
a set of optocouplers including a first optocoupler coupled between the output of the splitter and the first phase shifter.
20. The system of claim 19 , further comprising:
a controller that generates control signals for the set of phase shifters based on feedback of the recovery block.