Patent ID: 7881613

Claim:
An apparatus for tracking a wavelength in a passive optical subscriber network in which a central base station and at least one subscriber terminal are connected via a remote node, the apparatus comprising: a first wavelength aligning unit multiplexing and aligning wavelengths of optical signals from a plurality of single-mode optical sources of the central base station; a second wavelength aligning unit multiplexing and aligning wavelengths of optical signals transmitted to the remote node from a plurality of single-mode optical sources of the subscriber terminal; and a third wavelength aligning unit being included in the central base station, and demultiplexing and aligning wavelengths of optical signals from the second wavelength aligning unit, wherein the first wavelength aligning unit comprises: a partial reflector reflecting the multiplexed optical signals being transmitted downward to the subscriber terminal so that some portion of the optical power of the optical signals are returned to the single-mode optical sources of the central base station; a plurality of optical couplers respectively extracting the some portion of optical power of the optical signals returned from the partial reflector; a plurality of power monitors, each measuring an optical power level of one of the optical signals extracted by one of the optical couplers; and a plurality of thermoelectric coolers respectively increasing or decreasing temperatures of the single-mode optical sources of the central base station so that the optical power levels of the optical signals measured by the power monitors are increased.