Patent ID: 7542634

Claim:
Apparatus for adding wavelengths to a WDM signal, said apparatus comprising: a plurality of optical combination structures that each combines a set of N/P wavelengths into a single combined optical signal while maintaining a linear orthogonal polarization state for pairs of said wavelengths; wherein P is greater than one, N is a total number of wavelengths to be added to said WDM signal and where each of said N/P wavelengths is coupled to said optical combination structure by a separate input, and wherein each pair of said N/P wavelengths are input to said optical combination structure with linear orthogonal polarization, said optical combination structure further comprises: means for reducing noise level by causing the noise from each input to add incoherently; and an interferential filter for combining two adjacent multi-wavelength subbands of said N wavelengths; a first optical device including P input ports that combines a single combined output signal at an input at each of said P input ports into a single output signal, each of said P input ports accepting non-overlapping interleaved sets of N/P wavelengths; and an optical coupler that combines said single output signal with said WDM signal.