Patent ID: 7197246

Claim:
An optical loop-structured circuit having at least a plurality of looped optical transmission lines having at least a plurality of optical transmission line junctions from which at least three optical transmission lines extend, wherein at least one of said plurality of optical transmission line junctions has an optical device configured for performing at least a wavelength demultiplexing function, which is connected to said at least three optical transmission lines, so that said optical device serves as a same role as an optical coupler so as to reduce an optical power loss as compared to a 1:1 optical coupler when an optical signal is transmitted through one said optical transmission line junction, wherein at least two of said plurality of looped optical transmission lines are connected to an optical multiplexer/demultiplexer, whilst a single looped optical transmission line is separated by said at least two of said plurality of looped optical transmission lines from said optical multiplexer/demultiplexer, so that optical signals are individually transmitted along said plurality of looped optical transmission lines, and wherein all of said plurality of optical transmission line junctions have said optical devices.