Passive wavelength division multiplexing device for automatic wavelength locking and system thereof

A passive wavelength division multiplexing system for automatic wavelength locking, comprising an optical line terminal (OLT), one or more optical network units (ONUs) including a light source in which a lasing wavelength of a laser is adjusted by the thermo-optic effect, and a wavelength routing network for interconnecting the optical line terminal (OLT) and the optical network units (ONUs) through a single optical line,

• wherein the optical line terminal (OLT) comprises:
• an FSK Tx section configured to transmit its locked wavelength information using a frequency shift keying (FSK) which is carried on the amplitude of payload data within a given percentage (e.g., 10%);
• a first photo detection section configured to detect the intensity of a light having a specific wavelength transferred thereto from the optical network unit (ONU) through monitoring;
• and
• a first polymer OSA section configured to transmit the light having the specific wavelength detected by the first photo detection section using a polymer OAS, and
• wherein each of the optical network units (ONUs) comprises:
• a second photo detection section configured to receive the playload data from the optical line terminal (OLT) and convert the received playload data into an electrical signal;
• an FSK Rx section configured to detect only an FSK signal from the data into the electrical signal in the second photo detection section to extract the locked wavelength information;
• and
• a second polymer OSA section configured to transmit a light having a specific wavelength to the optical line terminal (OLT) while tuning a wavelength based on the locked wavelength information extracted in the FSK Rx section.