LOW-NOISE SEMICONDUCTOR OPTICAL AMPLIFIER

摘要

PROBLEM TO BE SOLVED: To provide a semiconductor optical amplifier with low noise characteristic. SOLUTION: A semiconductor optical amplifier in which signal light is made to fall on a semiconductor optical amplifier 2 into which forward current is injected, signal light amplified by the semiconductor optical amplifier 2 is outputted through a semiconductor saturable absorbing section 3 to which a reverse voltage is applied, wherein a part of the signal light is taken out and converted into an electric signal by means of a light-electricity changing circuit 6, and a reverse voltage is controlled by the electric signal.