Optical transmission line monitoring system and optical transmission line supervisory manner

摘要

PROBLEM TO BE SOLVED: To provide an optical transmission line monitor technology with high accuracy, without deteriorating a transmission characteristic of a main signal light in wavelength multiplex transmission by an optical amplifier relay system and moreover with decreased loss of a backward scattered light. SOLUTION: In the optical amplifier relay system of this invention where an optical fiber amplifier repeater, including an optical fiber amplifier, is inserted to a couple of incoming and outgoing optical fiber transmission lines and an optical signal is transmitted/revived between optical wavelength multiplex terminal stations, a monitor 2, including at least transmission reception sections 2a, 2b for a monitor optical pulse is placed in the optical wavelength multiplex terminal station 1, an optical circulator 17 and an optical fiber grating 18 are placed at the output terminal of the optical fiber amplifier 16 of each repeater 10 to lead a backward scattered light produced, while an optical signal propagates through an optical transmission line 4a o the optical fiber grating via the optical circulator, and only the backward scattered light of the monitor optical pulse is transmitted to the monitor 2 through an opposite optical transmission line 4b.