OPTICAL AMPLIFIER

摘要

PROBLEM TO BE SOLVED: To provide an optical amplifier for stably obtaining the test light with a high gain. SOLUTION: An optical circulator 2 for inputting/outputting the signal light is connected to one end of an optical amplifier unit for amplifying the light by multiplexing the light and an stimulation light from a stimulation light source 5 by a coupler 3 and inputting the multiplexed light to an optical fiber 4. A narrow band filter 7 for transmitting only the signal light and a reflector 6 reflecting only the signal light are connected to the other end of the amplifier unit so that the signal light is reciprocated through the fiber 4 to obtain a twice gain. Further, the signal light is passed twice through the narrow band filter so that a shield effect of an ASE becomes doubled.