OPTICAL ACCESS SYSTEM AND ACCESS NODE DEVICE AND USER NODE DEVICE

摘要

PROBLEM TO BE SOLVED: To realize a high speed wavelength multiplex optical access system of an inexpensive user node device without providing any light source whose wavelength is different in each user node device. SOLUTION: An access node device is provided with the light source of a non-modulated light (CW light), and this CW light is transmitted to the user node device. In the user node device, the CW light is modulated so that the frequencies (wavelength) of the light signal can be shifted by Δf from the CW light, modulated with incoming data, and transmitted to the access node device. In the access node device, only the incoming signal shifted only by the frequencies Δf is extracted by an optical filter so that the near-end reflected light of the CW light can be cut.