| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical amplifier with a broad-band gain spectrum with no loss of signal light wavelengths by causing a band reflector to reflect only such signal light as having wavelengths not separated by a demultiplexer and to transmit signal light having other wavelengths. SOLUTION: Signal light having wavelengths λb-λc passing through a transmission fiber 100 and reflected by a band reflector 206 enters into an optical circulator 205 to be guided downward, amplified in an amplifying section 207, and combined with signal light having wavelengths λa-λb and λc-λd in a multiplexer 208 adjacent to the section 207. Then, the multiplexer 208 multiplexes the signal light having the wavelengths λb-λc into the optical signal having the wavelength λa-λb and λc-λd while dropping no signal light wavelengths (channels). For example, a multiplexer whose branching ratio is 1:1 with no dependence on the wavelength (e.g. an optical fiber coupler) is used. Thus, an optical amplifier having a broad-band gain spectrum with no loss of signal wavelengths can be obtained. |
