Automatic Endless Polarization Controller For A Silicon-On-Insulator Platform

A photonic platform based polarization controller for providing a fixed target polarization of an input optical beam having first and second orthogonal polarization components, the polarization controller comprising:

• a polarization rotator splitter (PRS) for splitting the input optical beam into first and second feeds corresponding to the first and second orthogonal polarization components, respectively, wherein the first and second feeds have a same fixed state of polarization;
• a first phase shifter coupled to the PRS for providing a first optical phase delay between the first and second feeds based on a first control signal, and a first 2×2 optical coupler coupled to the first phase shifter for mixing the first and second feeds having the first optical phase delay therebetween, to provide third and fourth feeds;
• a second phase shifter coupled to the first 2×2 optical coupler for providing a second optical phase delay between the third and fourth feeds based on a second control signal, and a second 2×2 optical coupler coupled to the second phase shifter for mixing the third and fourth feeds having the second optical phase delay therebetween, to provide fifth and sixth feeds;
• a third phase shifter coupled to the second 2×2 optical coupler for providing a third optical phase delay between the fifth and sixth feeds based on a third control signal, and an output optical coupler coupled to the third phase shifter for mixing the fifth and sixth feeds having the third optical phase delay therebetween, to provide an output optical beam having the fixed target polarization;
• and
• an optical tap optically coupled to the output optical coupler for splitting a portion of the output optical beam.

A method of providing a fixed target polarization of an optical beam having first and second orthogonal polarization components, the method comprising:

• splitting the optical beam into first and second feeds corresponding to the first and second orthogonal polarization components, respectively, such that the first and second feeds have a same fixed state of polarization;
• adjusting a first optical phase delay between the first and second feeds based on a first control signal;
• mixing the first and second feeds having the first optical phase delay therebetween to provide third and fourth feeds;
• adjusting a second optical phase delay between the third and fourth feeds based on a second control signal;
• mixing the third and fourth feeds having the second optical phase delay therebetween to provide fifth and sixth feeds;
• adjusting a third optical phase delay between the fifth and sixth feeds based on a third control signal;
• mixing the fifth and sixth feeds having the third optical phase delay therebetween to provide the optical beam having the fixed target polarization;
• and
• splitting a portion of the optical beam using an optical tap.