Anti-PDL beam swapping

An optical beam swapping device comprising:

• a polarization diversity unit for receiving an input optical signal and producing a first beam of light and a second beam of light therefrom, the first and second beams of light having a same polarization state;
• a beam swapping element disposed for receiving the first and second beams of light and for redirecting the two beams of light to a same point;
• a modulator disposed substantially about the same point for modifying the first and second beams of light;
• and
• a reflective surface for reflecting the two modified beams of light back to the polarization diversity unit where they are combined to form an output optical signal, wherein each of the first and second beams of light traces out the other's optical path in reverse.

An optical beam swapping device comprising:

• a polarization diversity unit for receiving an input optical signal and producing a first and a second beam of light therefrom;
• a beam swapping element disposed for receiving the first and second beams of light and for redirecting the two beams of light to a same point;
• an optical component having a local spatial dependence on an optical property disposed substantially at the same point;
• and
• a reflective surface disposed for receiving the two beams of light directed to the same point and reflecting them back to the polarization diversity unit where they are combined to form an output optical signal, wherein each of the first and second beams of light is reflected in a backward propagating direction along an optical path that the other beam of light followed to the reflective surface in a forward propagating direction.

An optical device comprising:

• polarization diversity means for providing first and second spatially separated beams of light from a single input beam of light;
• reflective means disposed for receiving the first and second beams of light and redirecting them back to the polarization diversity means where they are recombined into a single output beam of light;
• and
• a beam swapping element optically disposed between the polarization diversity means and the reflecting means for forcing the first and second beams of light to swap optical paths upon reflection from the reflecting means.