Patent ID: 6671084
Filing Date: 2003-12-30
Classification: H01S,H04B,H04J

Abstract:
An optical transmission system, comprising:a transmitting apparatus; a receiving apparatus; and a relay apparatus connected with the transmitting apparatus and the receiving apparatus via an optical fiber; wherein the transmitting apparatus transmits a wavelength-multiplexed light which is multiplexed with signals having different wavelengths to the receiving apparatus via the relay apparatus; at least one of the relay apparatus and the receiving apparatus comparing a first light-intensity of the wavelength-multiplexed light with a first threshold, and comparing a second light-intensity of a signal light having a predetermined wavelength extracted from the wavelength-multiplexed light with a second threshold, and (1) if the first light-intensity is at least equal to the first threshold, outputs a normal signal, (2) if the first light-intensity is smaller than the first threshold and the second light-intensity is at least equal to the second threshold, outputs a first alarm signal, and (3) if the first light-intensity is smaller than the first threshold and the second light-intensity is smaller than the second threshold, outputs a second alarm signal.