| 摘要 |
An optical routing switch employs a polarization-dependent routing (PDR) element formed by joining a plurality of prisms to form a substantially X-shaped interface between the prisms. A polarizing beam splitter (PBS) coating is applied to the interface, so that the interface transmits light having a first polarization along a transmitted optical path and reflects lights having a second, orthogonal polarization along a reflected optical path. A plurality of input/output ports are aligned to communicate optical signals along transmitted and reflected optical paths of the PDR element. Each input port has a birefringent element spatially separating the input optical signal into a pair of orthogonally-polarized beams, and a polarization rotator rotating the polarization of at least one of the pair of beams so that both beams have substantially the same polarization determined by the control state of the optical routing switch. Similarly, each output port has a polarization rotator that rotates the polarization of at least one of the pair of beams exiting the PDR element so that the beams have substantially orthogonal polarizations, and a birefringent element that combines the orthogonally-polarized beams into an output optical signal. Two PDR elements can be combined in an offset relationship to create a double ring add/drop switch or east/west protection switch.
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