An optical fiber amplifier is proposed comprising at least one pump light source (3), at least one amplifying fiber section (10), and at least one coupler (8) which establishes a connection between the input fiber (1) of the fiber type I, the pump light source (3), the amplifying fiber section (10), and the output fiber (12) of the fiber type I. The amplifying fiber section (10) consists of a fiber type II, and the the splices (2, 11) between the fiber type I and the fiber type II are arranged relative to the amplifying fiber section (10) such that light propagated in the direction opposite to the signal direction and light propagated in the signal direction passes through means absorbent of short wavelengths before it reaches the splices.