Patent ID: 7058304

Claim:
A bi-directional cross-connect apparatus comprising: a first port; a second port; a third port; a fourth port; and routing means for directing signals comprising wavelength channels from a first subset of optical frequencies between the first port and the third port, and between the second port and the fourth port, and for directing signals comprising wavelength channels from a second set of optical frequencies, interleaved with the first subset of optical frequencies, between the first port and the fourth port, and between the second port and the third port; wherein the routing means comprises a birefringent crystal interleaver including a first birefringent element of length L, and a second birefringent element of length 2L, wherein crystal axes of the first and second birefringent elements are oriented differently; whereby the polarization of the wavelength channels in the first subset of optical frequencies is rotated by substantially 90°, while the polarization of the wavelength channels in the second subset of optical frequencies is substantially unchanged.