an optical fiber connected to a hub via at least one of an input of a demultiplexer having N outputs and an output of a multiplexer having N inputs;

a first communications station which processes spectral multiplexes of modulated optical signals having different wavelengths via a first type coupling means; and

a second communications station which processes spectral multiplexes of modulated optical signals having different wavelengths via a second type coupling means,

wherein said first and second communications stations process spectral multiplexes of modulated optical signals from a given one of P disjoint bands of wavelengths,

wherein said first type coupling means is at least one of a 2×1 band multiplexer and demultiplexer comprising:

at least one of an output and input connected to a downstream portion of said optical fiber;

at least one of a first input and a first output connected to said first communications station which uses a band of wavelengths from among the P disjoint bands of wavelengths; and

at least one of a second input and a second output connected to an upstream portion of said optical fiber which uses channels having wavelengths different from wavelengths of channels passing through the at least one of said first input and said first output,

wherein said at least one of a demultiplexer and multiplexer is of periodic type which processes at the at least one of N outputs and inputs channels of wavelengths that belong to distinct sets of P wavelengths, each wavelength of a set belonging to a distinct band of said P disjoint bands of wavelengths, and

wherein N and P are integers.