Patent ID: 7418168

Claim:
An optical add/drop module (OADM) for use in connection with a multiplexed optical signal, the optical add/drop module comprising: a drop portion that includes an output port; and an add portion including an input port that is connected with the output port of the drop portion, the add portion configured to receive, as an input, at least one channel extracted by the drop portion, the add portion configured to combine the at least one channel extracted by the drop portion with another channel associated with the multiplexed optical signal, and the add portion having a plurality of stages that each include at least one interleaver, the plurality of stages including a stage that comprises a first interleaver in series with a second interleaver, and the plurality of stages being disposed together in a cascade arrangement, wherein at least one of the stages of the add portion comprises a plurality of fused fiber interleavers, and wherein at least one interleaver of the add portion comprises a thin film interleaver including: a plurality of cavities, each cavity having a plurality of thin film layers and a spacer; and a final cavity comprising a spacer having a matching layer designed with an index of refraction that substantially matches the thin film interleaver to another medium.