| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an optical fiber amplifier having a suppressed wavelength transition and high reliability. SOLUTION: Output signal light of an output-side light isolator 2 is made to pass through a band light filter 5 allowing to pass through the whole wavelength band of transmitting light. When the wide band light filter 5 is used, its amplification efficiency becomes lower than the case of using a narrow band light filter. However, even in the case of using the narrow band light filter, it requires to use a light attenuator of +10dBm level for attenuating the amplification gain of a strong signal output so as to match with performance of a light-receiving element in a receiver so that amplification efficiency does not become a problem as a result. That is to say only the disadvantage due to the use of the narrow band light filter is eliminated by using the wide band light filter.</p> |
