Patent ID: 7003229

Claim:
A method for optimizing the sequence order of optical passive filters in WDM (Wavelength Division Multiplex) multi-channel transmission systems, said optical passive filters making up mux/demux structures at nodes of the WDM system, the method comprising: setting a number of parameters identifying the WDM system; defining the attenuation profile over different channels of the WDM system, by using said parameters; determining an order sequence of the different channels in a mux/demux structure from the attenuation profile; determining an insertion loss profile of the different channels from the order sequence; determining a minimum span length between nodes resulting from applying said order sequence; wherein the parameters identifying the WDM system comprise: Number of channels: N; Set of wavelengths: λ 1 . . . λ N [nm] of the N channels; Fiber loss profile: F loss (λ) [dB/km] of the optical fiber used in the WDM system; Insertion loss model: I loss1 , and Δ att [dB] of the mux/demux structure, where I loss value gives the losses measured between the input (common) port and the N outputs: I loss (n)=I loss1 +Δ att (n−1), I loss1 is the insertion loss of the first port of the structure; Δ att is the incremental attenuation between to adjacent ports of the structure; n is the port position; Span length target: Slt [km] as required for the WDM system; Power Budget: Pb [dB] used between the nodes of the WDM system; Intermediate nodes: Inodes, maximum number of intermediate non-regenerative nodes.