摘要:
The present invention relates to an isolated polarization beam splitter or combiner, for joining light from different inputs into one common port, and for dividing a beam of light into orthogonal polarizations. In both modes of operation, the splitter/combiner provides isolation preventing transmission of light in a reverse direction. As a splitter, a beam of light is separated through a birefringent material into sub-beams of orthogonal polarization components, and each sub-beam is passed through a non-reciprocal polarization rotator to rotate the polarization so that a reflected beam, or other counter-transmitted light cannot return on the same path through the birefringent material to the source. As a combiner, two separate beams of light are launched with known orthogonal polarizations into a first birefringent material, passed through a non-reciprocal polarization rotator and then combined as orthogonal polarizations into a single output port. Advantageously, by providing the splitting or combining function in a same isolating device, insertion losses are reduced and the device is smaller and more cost effective. As a further advantage, a polarization beam splitter/combiner is provided in which the optical path length for the two separated orthogonal polarizations traveling through a birefringent crystal is equal, while still permitting the economical use of birefringent crystals with an uncollimated beam of light.
摘要:
The present invention relates to an isolated polarization beam splitter or combiner, for joining light from different inputs into one common port, and for dividing a beam of light into orthogonal polarizations. In both modes of operation, the splitter/combiner provides isolation preventing transmission of light in a reverse direction. As a splitter, a beam of light is separated through a birefringent material into sub-beams of orthogonal polarization components, and each sub-beam is passed through a non-reciprocal polarization rotator to rotate the polarization so that a reflected beam, or other counter-transmitted light cannot return on the same path through the birefringent material to the source. As a combiner, two separate beams of light are launched with known orthogonal polarizations into a first birefringent material, passed through a non-reciprocal polarization rotator and then combined as orthogonal polarizations into a single output port. Advantageously, by providing the splitting or combining function in a same isolating device, insertion losses are reduced and the device is smaller and more cost effective. As a further advantage, a polarization beam splitter/combiner is provided in which the optical path length for the two separated orthogonal polarizations traveling through a birefringent crystal is equal, while still permitting the economical use of birefringent crystals with an uncollimated beam of light.
摘要:
This invention relates to elements such as birefringent crystals, which are used to separate a non-collimated input beam into two orthogonally polarized sub-beams or to combine two orthogonally polarized beams into a single beam. The optical device lessens or obviates the optical path length difference encountered in prior art devices and provides a polarization beam splitter / combiner that has substantially same optical path lengths for two split or combined beams propagating therethrough. Alternatively, the device is designed to provide a selected path length difference to compensate for polarization mode dispersion in other optical devices. The polarization beam splitter/combiner in accordance with the invention has a first uniaxial crystal having an o-ray path and an e-ray path and having the first port disposed at an end face thereof; a second uniaxial crystal having an o-ray path and an e-ray path, the e-ray path of the second uniaxial crystal being optically coupled with the o-ray path of the first uniaxial crystal and the o-ray path of the second uniaxial crystal being optically coupled with the e-ray path of the first uniaxial crystal. Alternatively, the axis of the second crystal is aligned in such a manner that the o- ray path is retarded by an extraordinary index of refraction of the crystal and the e-ray path is retarded by an ordinary index of refraction to equalize the optical path lengths.
摘要:
This invention relates to elements such as birefringent crystals, which are used to separate a non-collimated input beam into two orthogonally polarized sub-beams or to combine two orthogonally polarized beams into a single beam. The optical device lessens or obviates the optical path length difference encountered in prior art devices and provides a polarization beam splitter / combiner that has substantially same optical path lengths for two split or combined beams propagating therethrough. Alternatively, the device is designed to provide a selected path length difference to compensate for polarization mode dispersion in other optical devices. The polarization beam splitter/combiner in accordance with the invention has a first uniaxial crystal having an o-ray path and an e-ray path and having the first port disposed at an end face thereof; a second uniaxial crystal having an o-ray path and an e-ray path, the e-ray path of the second uniaxial crystal being optically coupled with the o-ray path of the first uniaxial crystal and the o-ray path of the second uniaxial crystal being optically coupled with the e-ray path of the first uniaxial crystal. Alternatively, the axis of the second crystal is aligned in such a manner that the o- ray path is retarded by an extraordinary index of refraction of the crystal and the e-ray path is retarded by an ordinary index of refraction to equalize the optical path lengths.