Patent ID: 7254340

Claim:
An optical wavelength tracking apparatus in a wavelength division multiplexed (WDM) passive optical network (PON) in which a central office (CO) having a multi-frequency light source is connected to a plurality of optical network units (ONUs) having loop-back light sources through a WDM multiplexer/demultiplexer (MUX/DEMUX) in a remote node (RN), the apparatus comprising: a first optical power measurer for measuring a power level of a downstream WDM optical signal for the plurality of ONUs that is directed from the multi-frequency light source to the WDM MUX/DEMUX; a second optical power measurer for measuring a power level of an upstream WDM optical signal received from the loop-back light sources of the ONUs through the WDM MUX/DEMUX; and a control unit for controlling the WDM wavelengths of the multi-frequency light source and the WDM MUX/DEMUX to be nearly identical in order to minimize the difference between the power levels of the measured downstream and upstream WDM optical signals.