| 摘要 |
PROBLEM TO BE SOLVED: To provide a fixed gain type optical amplifier that has flat gain in an optical communication system. SOLUTION: This amplifier is provided with a fixed gain amplifying part 100, where an optical signal is inputted to apply a compensation signal and a gain is fixed, so that the input signal has the same output by each channel, a second isolator 22 that enables a signal light inputted from the gain fixed amplifier to pass through and enables a light coming from the opposite direction to be blocked, a filter 51 for flattening gain that inputs a signal form the second isolator and makes its output gain spectrum which is flat in shape, and a post- amplifying part 200 for amplifying a signal of the filter 51 for flattening the gain. While the inversion of state concentration of the amplifier is kept constant by changing the input signal, the gain is automatically fixed and the signal band is made broad to increase the transmission volume, so that the gain is made flat. |
