Optical network comprising node groups and an analog repeater node unit

Abstract

In an optical network comprising terminator nodes (15(A1) etc) assigned with frequency bands for transmitting transmission signals subcarrier-frequency multiplexed on optical signals of a predetermined number of optical wavelengths from one node to at least another, the nodes are grouped into terminator node groups (11(A, B, C)), each assigned with selected wavelengths among the optical wavelengths except a specific wavelength specific thereto. One node group (11(A)) transmits outgoing signals of the selected wavelengths to an analog repeater node (17(A)) for supplying ingoing signals of the specific wavelength to a common optical coupler (13). Supplied as outcoming signals of various wavelengths with such outgoing signals of other node groups (11(B, C)) directed to the coupler, the repeater node supplies the one node group with incoming signals of the specific wavelength. Preferably, the repeater node comprises a photodetector detecting as send-in (receive-in) signals the transmission signals carried on the outgoing (outcoming) signals, bandbass filters for filtering the send-in (receive-in) signals into intermediate signals, frequency converters for the intermediate signals to produce send-out (receive-out) signals according to a demand assign scheme, and a light source producing the ingoing (incoming) signals carrying the send-out (receive-out) signals.