Optical circulator array
Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for optical communications. In one aspect, an optical circulator array includes a plurality of stacked three port circulators each having a respective first port of a first port array, a respective second port of a second port array, and a respective third port of a third port array, wherein each of the plurality of stacked three port circulators share optical components including: a first Wollaston prism coupled to the first port array, a first lens, a first half wave plate, a polarization dependent beam path separator, a second half wave plate, a second lens, a propagation direction dependent polarization rotation assembly, a second Wollaston prism coupled to the second port array, and a third Wollaston prism coupled to the third port array.
1. An optical circulator array comprising:
a plurality of stacked three port circulators each having a respective first port of a first port array, a respective second port of a second port array, and a respective third port of a third port array, wherein each of the plurality of stacked three port circulators share optical components including:
a first Wollaston prism coupled to the first port array,
a first lens,
a first half wave plate,
a polarization dependent beam path separator,
a second half wave plate,
a second lens,
a propagation direction dependent polarization rotation assembly,
a second Wollaston prism coupled to the second port array,
a third Wollaston prism coupled to the third port array,
a second propagation direction dependent polarization rotation assembly coupled to the first port; and
a third propagation direction dependent polarization rotation assembly coupled to the third port.
2. The optical circulator array of claim 1 , wherein the propagation direction dependent polarization rotation assembly includes a Faraday rotator and a half wave plate.
3. The optical circulator array of claim 1 , wherein each port array includes one or more thermal expansion core (TEC) fibers.
4. The optical circulator array of claim 1 , wherein the polarization dependent beam path separator comprises a birefringence wedge pair.
5. The optical circulator array of claim 4 , wherein the birefringence wedge pair comprises:
a first wedge optically coupled to a first side of the birefringence wedge pair; and
a second wedge optically coupled to a second side of the birefringence wedge pair,
wherein the first wedge and the second wedge correct parallelization of light beams passing through the optical circulator array.
6. The optical circulator array of claim 1 , wherein the polarization dependent beam path separator comprises an optical beam separator with polarization dependent coating.
7. The optical circulator array of claim 3 , wherein the TEC fibers, first lens, second lens, and polarization dependent beam path separator are positioned in a double telemetric configuration layout.
8. The optical circulator array of claim 1 , wherein the polarization dependent beam path separator provides beam path routing from the first port to the second port and from the second port to the third port based on a polarization orientation of incident light beams.
9. The optical circulator array of claim 1 , wherein the polarization dependent beam path separator is optically coupled between the first lens and the second lens.
10. The optical circulator array of claim 1 , wherein the propagation direction dependent polarization rotation assembly is optically coupled between the second Wollaston prism and the second lens.
11. The optical circulator array of claim 1 , wherein the second propagation direction dependent polarization rotation assembly provides isolation to reduce light leakage along a path from the second port to the first port.
12. The optical circulator array of claim 1 , wherein the third propagation direction dependent polarization rotation assembly provides isolation to reduce light leakage along a path from the third port to the second port.
13. The optical circulator of claim 1 , wherein light beams input at the first port are randomly polarized and wherein the first Wollaston prism and the first half wave plate provide polarization conditioning.
14. The optical circulator of claim 1 , wherein the second propagation direction dependent polarization rotation assembly is optically coupled between the first Wollaston prism and the first lens, and the third propagation direction dependent polarization rotation assembly is optically coupled between the third Wollaston prism and the first lens.
15. The optical circulator array of claim 1 , wherein:
the first Wollaston prism includes a pair of wedge prisms having optic axes that are perpendicular to each other such that the light beam exiting the Wollaston prism diverges based on polarization direction such that two orthogonally polarized light beams result; and
the first half wave plate is disposed to rotate one of the two orthogonally polarized light beams; and
the second half wave plate is disposed to rotate one of the other of the two orthogonally polarized light beams.