Polarization interleaver

The present invention relates generally to WDM and DWDM communication systems, and more generally to a polarization interleaver employed in such systems. A method and apparatus provides a WDM optical signal having a plurality of channels with a pair-wise orthogonal polarization state. The method begins by receiving a plurality of unpolarized optical wavelengths defining a plurality of optical channels separated by a prescribed channel spacing. A polarization wavelength dependent shift is imparted to the optical wavelengths, which is substantially equal to a particular fraction of the prescribed channel spacing.