Patent ID: 7254335

Claim:
A node comprising: a series connection of elements E i , i=1, 2, . . . N, where N is greater than 1, forming a first optical path, where each of said elements E i injects an optical signal of band Λ 1 , and where Λ i is disjoint from Λ j for all i≠j; a series connection of elements F i , i=1, 2, . . . N, forming a second optical path, where each of said elements F i extracts an optical signal of band Λ i ; a plurality of transmitters T i , i=1, 2, . . . N, coupled to said elements E i on a one to one basis; and a plurality of a receivers R i , i=1, 2, . . . N, coupled to said elements F i on a one to one basis; wherein a collection of elements that includes element E i , element F i , transmitter T i , and receiver R i are housed in a single equipment module M i , resulting in said node comprising a serially interconnected set of modules M i , i=1, 2, . . . N, with said interconnected set having an add-in node input port that is connected to module M 1 , a drop-out node output port that is connected to module M 1 , an add-in node output port that is connected to module M N , and a drop-out node input port that is connected to module M N .