OPTICAL FIBER AMPLIFIER

摘要

PROBLEM TO BE SOLVED: To avoid cost increase and to prevent optical oscillation from being caused even when high level optical amplification is conducted by using an optical multiplexer/demultiplexer of signal light reflection type. SOLUTION: A signal light given to an input optical fiber 11 propagates to an erbium doped optical fiber 13 via a 1st isolator 12. An optical multiplexer/ demultiplexer 15 to which one terminal of the erbium doped optical fiber 13 is connected is provided with a dielectric multi-layer filter. A stimulated light from a stimulation light source 14 transmits through a dielectric multi-layer film filter of the optical multiplexer/demultiplexer 15 and is made incident to the erbium doped optical fiber 13 to stimulate erbium atoms in the erbium doped optical fiber 13. In this case, the amplified in the erbium doped optical fiber 13 is reflected in the dielectric multi-layer film filter of the optical multiplexer/demultiplexer 15 and outputted via a 2nd isolator 17 provided to an optical signal output optical fiber 16, then the return light of the signal light to the erbium doped optical fiber 13 is reduced.