Low-cost WDM source with an incoherent light injected fabry-perot laser diode

An optical transmission system in a passive optical network, comprising:

• a remote node comprising a first demultiplexer and an optical circulator coupled to the first demultiplexer;
• a central office comprising one or more injection incoherent light sources that generate one or more injection incoherent light signals, a second demultiplexer, and one or more optical receivers that are optically coupled at the output ends of the second demultiplexer;
• and
• one or more light sources optically coupled to ports of the first demultiplexer, wherein the first demultiplexer receives output signals from the one or more light sources capable of lasing to generate an upstream signal and a first light source from the one or more light sources receives a first injection incoherent light signal generated by the one or more injection incoherent light sources to suppress one or more lasing modes outside of a bandwidth of the first injected incoherent light signal and to lock an output wavelength of the first light source to within the bandwidth of the first injected incoherent light signal;
• a first optical fiber to connect the central office with the remote node, wherein the second demultiplexer receives the upstream signal and demultiplexes the upstream signal to the one or more optical receivers, wherein the first light source is configured such that a side mode suppression ratio of the wavelength locked output of the first light source is increased by increasing a power of the first injection incoherent light signal, wherein the
• optical circulator is optically coupled between the one or more injection incoherent light sources, the first demultiplexer and the second demultiplexer to separate the upstream signal delivered to the second demultiplexer from the first injection incoherent light signal delivered to the first demultiplexer.