Systems and methods for photonic polarization-separating apparatuses for optical network applications

1. An integrated photonic polarization-separating apparatus comprising:

a first waveguide polarization beam splitter (PBS) having a first port, a second port, a third port, and a fourth port;

a first polarization rotator optically coupled to the first port of the first waveguide PBS;

a waveguide comprising silicon;

a first Faraday rotator optically coupled to the first polarization rotator using the waveguide comprising silicon;

a second polarization rotator optically coupled to the second port of the first waveguide PBS;

a second Faraday rotator optically coupled to the second polarization rotator;

a second waveguide PBS having a first port, a second port, a third port, and a fourth port, wherein the third port is optically coupled to the first Faraday rotator and the fourth port is optically coupled to the second Faraday rotator; and

wherein the first waveguide PBS, the first polarization rotator, the first Faraday rotator, the second polarization rotator, the second Faraday rotator, and the second waveguide PBS are integrated on a semiconductor substrate.

2. The integrated photonic polarization-separating apparatus of claim 1 wherein each of the first polarization rotator and the second polarization rotator comprises a 45-degree polarization rotator.

3. The integrated photonic polarization-separating apparatus of claim 2 wherein each of the first Faraday rotator and the second Faraday rotator comprises a negative 45-degree Faraday rotator.

4. The integrated photonic polarization-separating apparatus of claim 1 further comprising a third waveguide PBS having a first port, a second port, a third port, and a fourth port, wherein the third port is optically coupled to the second port of the second waveguide PBS.

5. The integrated photonic polarization-separating apparatus of claim 4 further comprising:

a third polarization rotator optically coupled to the first port of the third waveguide PBS, and

a fourth polarization rotator optically coupled to the second port of the third waveguide PBS.

6. The integrated photonic polarization-separating apparatus of claim 5 wherein each of the third polarization rotator and the fourth polarization rotator comprises a 90-degree polarization rotator.

7. The integrated photonic polarization-separating apparatus of claim 1 further comprising:

a third polarization rotator optically coupled to the second port of the second waveguide PBS; and

a third waveguide PBS having a first port, a second port, a third port, and a fourth port, wherein the third port is optically coupled to the third polarization rotator.

8. The integrated photonic polarization-separating apparatus of claim 7 wherein the third polarization rotator comprises a 90-degree polarization rotator.

9. The integrated photonic polarization-separating apparatus of claim 7 further comprising:

a first receiver optically coupled to the first port of the third waveguide PBS; and

a second receiver optically coupled to the second port of the third waveguide PBS.

10. The integrated photonic polarization-separating apparatus of claim 1 further comprising a laser optically coupled to the first port of the second waveguide PBS.

11. The integrated photonic polarization-separating apparatus of claim 1 wherein the semiconductor substrate is a silicon-on-insulator (SOI) substrate.

12. The integrated photonic polarization-separating apparatus of claim 1 , wherein:

the semiconductor substrate comprises a handle portion;

the handle portion comprises silicon;

the semiconductor substrate comprise an insulation layer next to the handle portion;

the insulation layer comprises an oxide material; and

the waveguide comprising silicon is next to the insulation layer.