Abstract: Disclosed is an optical network system including a upper network equipment, a lower network equipment, and a plurality of transfer network equipments connecting the upper network equipment and the lower network equipment through independent optical links, wherein the lower network equipment performs switching such that transmission and reception of an optical signal are performed through an optical link of a standby line when a failure occurs in at least one of an optical link used as a working line, an optical interface device associated with the working line in the upper network equipment, and a transfer network equipment associated with the working line.

Abstract: The present invention relates to a passive wavelength division multiplexing device for automatic wavelength locking and a system thereof including an optical multiplexer, an optical filter, an integrated optical receiver monitor, and a tunable optical transmitter. Through wavelength locking that adjusts a wavelength of an optical signal, which changes according to an external environment such as a temperature change, into a wavelength of an optical signal having the maximum optical intensity, communication quality may be maximized by securing a stable communication channel, a locking time and a communication channel setting time may be reduced, and more robust locking may be guaranteed.

Abstract: The present invention relates to a passive wavelength division multiplexing device for automatic wavelength locking and a system thereof including an optical multiplexer, an optical filter, an integrated optical receiver monitor, and a tunable optical transmitter. Through wavelength locking that adjusts a wavelength of an optical signal, which changes according to an external environment such as a temperature change, into a wavelength of an optical signal having the maximum optical intensity, communication quality may be maximized by securing a stable communication channel, a locking time and a communication channel setting time may be reduced, and more robust locking may be guaranteed.