Patent ID: 8301040

Claim:
An optical transmission system using Raman optical amplification, which is configured to include an optical line terminal, a plurality of optical network units connected to the optical line terminal through an optical fiber, and a WDM (wavelength division multiplexer) which multiplexes and demultiplexes signal lights between the optical line terminal and the optical network units in a WDM-PON (passive optical network) topology, wherein the optical line terminal comprises: a continuous light source which supplies to the optical network units through the optical fiber, continuous lights having the same wavelengths as uplink signal lights from the optical network units to the optical line terminal; and a pumping light source which supplies to the optical fiber, pumping lights which are used to excite the continuous lights from the continuous light source, and wherein each of the optical network units comprises an external modulator which modulates the continuous lights from the optical line terminal and outputs the modulated continuous lights as the uplink signal lights to the optical line terminal.