Optical transmission system and optical amplifying apparatus, optical amplifying unit, and optical coupler for the same

摘要

By the signal light of branching the input signal light into a signal light of the signal light and the L-band of the C-band by the optical branching unit and, the C-band in the optical amplifiers for C band, an optical amplifier for a signal light in the L-band L-band each optical amplifier by. The amplified signal light is output are multiplexed by the optical sum discarded. Since the L-band backward ASE light generated upon optical amplification in the optical amplifier is cut off by the optical filter provided between the optical branching unit for, the backward ASE light is inverted by being prevented from the input, which is amplified by an optical amplifier for C-band , a reduction in the noise figure (deterioration) is controlled. ; The optical communication system, optical amplifier, optical fiber, an optical amplifying unit, the optical coupler