The network comprises an optical ring link (F) and a concentrator (HUB) that sends via one end of the link "downlink" optical signals carried by respective wavelengths and receives "uplink" optical signals via the other end of the link. The link is divided into a plurality of segments (FS1-FS4) separated by access nodes (AN1-AN3) for receivers (RX) of downlink optical signals and for senders (TX) of uplink optical signals. Each access node comprises coupling means that are not wavelength-selective for coupling the segment on the upstream side of the node to the segment on the downstream side and to the receivers and to couple the senders (TX) to the segment on the downstream side. The downlink optical signals are carried by wavelengths belonging to a set of predefined wavelengths. To optimize the use of spectral resources, a rejection filter (NF) is inserted into a segment to reject a portion of the wavelengths of said set of wavelengths. The senders (TX) of stations associated with nodes on the downstream side of the segment then adapted produce uplink optical signals carried by respective wavelengths rejected by the rejection filter (NF). The invention is applicable to optical metropolitan access networks in particular.